#help-with-audio
glacial spruce
Yup, Multiwatt type package. It's a Sanyo LA4507.
Looks like everybody has the short-form data sheet, ChipDocs has the detailed one but they want you to "register" before they'll share it.
light crag
Where is the Pinout
glacial spruce
I suspect the amplifier chip itself is fine, and something else is causing the distortion, which is why it's a good idea to test out the amplifier with a known good signal.
I suspect the pinout is the usual one (power on pin 8, ground on pin 14, channel 1 input on pin 2, frequency trim on pin 3, feedback on pin 4, bias on pin 5, output on pin 6, channel 2 similar)
glacial spruce
Ah, different pinout, but looks like you found enough to proceed
light crag
I think the radio don't get power it's dead like nothing happen ๐ค
light crag
I think i figured out the problem
The switch you switch between radio and cassette
There was voltage in but not out I think i need a replacement
Hmmm I am sure this was the problem
light crag
It has 24 pins and its 3 way
glacial spruce
Ah, old cheap slide switch. Should be able to replace that somehow. I figured you would want to switch out stuff in the process of updating it.
light crag
Yeah
light crag
Do you know what type of switch it is
light crag
I think it's 6 pole 3 way
glacial spruce
You're probably right: 6P3T slide switch
outer gate
hey everyone, quick question. Would you rather step up voltage or step down voltage going to a dac?
glacial spruce
Normally I'd rather step down, which is more likely to reduce noise (but not always, there are a lot of factors in play)
Since it's to a DAC, it's probably digital data, so noise is less like to be an issue than on the analog side.
outer gate
I would agree. Thanks for the reassurance!
final yoke
No matter which method you use you should add a linear regulator in the end just for increased stability
But I'd use step down
outer gate
๐
light crag
@glacial spruce I tried to find that switch only find this not really right :(
glacial spruce
The switch was probably customized by the switch manufacturer for that circuit board. I figured you would be comfortable adapting some other switch. What I'd probably do is either a) use a rotary switch and run wires to the board (shielded ones for the signal wires to avoid interference), or b) figure out which poles I actually need for the new build and just hook up those to a simpler switch.
glacial spruce
I do a lot of shopping by images
One of these might do too https://media.digikey.com/Photos/Grayhill Photos/71BD30-02 SERIES.JPG
light crag
These switches are expensive 20โฌ
Also i could do something like that too
Have a rotatry
Not oem but it will work
glacial spruce
Yes, they are expensive unless you can salvage one somewhere (like an old serial switch box). However, you might not need all those poles and throws, depending on the configuration you intend to build.
A lot of these integrated units just run a lot of signals to a single switch because in volume it saves money. However, if you're adapting the design, you might find out that one pole is used to do something like light an LED or switch between AM and FM in the radio section. If you don't want AM reception, you wouldn't need that pole at all.
light crag
Yeah I should find a schematic
Am is pretty much useless not many channels there
There a radio port and that port it most interesting because I could just wire up a Bluetooth thing to that port without any mods
It doesn't have am but it has
FM sw wm lw
I was a bit confused firts why 2 radio
But realize it's that port
outer gate
I see with a few portable speakers they use a standard 3.7v lithium battery, but then step up the voltage to around 12 volts to the amplifier. Does that cause noise/reduce the sound quality?
glacial spruce
It can cause noise, but careful circuit design, layout, and shielding can avoid those problems.
outer gate
Great, thanks again!
tame oriole
Hi! I am looking for some help with the WaveHC Library. I followed the steps to format my SD card as FAT32, placed the file in 8.3 naming structure, and tested using the โSDReadTest.inoโ example sketch. Once I did this I got the below response with errorCode โ3":
Card type: SDHC
Manufacturer ID: 3
OEM ID: SD
Product: SB16G
Version: 8.0
Serial number: 139322610
Manufacturing date: 3/2020
card size: 31116288 (512 byte blocks)
partion,boot,type,start,length
1,0,C,8192,31108096
2,0,0,0,0
read partition table failedSD error
errorCode: 3
errorData: 0```
I was curious where the issue was, because Iโm building my own PCB, so I broke it down and decided to start debugging with the SD circuit and test that alone, then move to the DAC & the OpAmp. I checked out the SD.h library with the โCardInfoโ example worked correctly, displaying the card info and file structure as SDHC & FAT32.
So the question is, is there documentation on the specific error codes for the WaveHC library? What is "errorCode: 3โ correspond too? Is there something blatant that I am missing?
Thanks in advance for all the help on this. Yโall rock.Here are a few links to help:
- WaveHC Library: https://github.com/adafruit/WaveHC
- SDReadTest.ino: https://github.com/adafruit/WaveHC/tree/master/examples/SdReadTest
- SD. h Library: https://www.arduino.cc/en/reference/SD
- CardInfo sketch: https://www.arduino.cc/en/Tutorial/CardInfo
jagged yew
Hello there, My name is Felipe, I'm from Chile and I'm looking to develop a solution for a wireless BT microphone that can process the signal in realtime to apply some filters. Right now I have an esp32 pico d4 with a SGTL5000 codec. I'm having problems with how to do the filtering stage. I have some doubts, so please if someone can guide me with this would be great. The audio imput from the mic is 48 kHz , that the "ideal" samplerate so how can I process this in realtime(entering from the mic input form the codec and output from that same codec to a headphone? I only need 5 filters, I was thinking in some options: Does the ESP32 have the power to do this in realtime?, or I was looking at the STM32F303CCT6 to work like a DSP with the filters in it. What do you guys recommend?
solemn flint
jagged yew
Thank you, I will take a look
I just realized that the SGTL5000 does have a parametric eq included
I have to calculate the filter coefficients to design some filters to try
night creek
If anyone is able to help โ I'm hoping to confirm a couple things:
- Will Adafruit's fork of the PJRC's Audio Library natively work with the Feather M4 using the Music Maker Feather Wing?
I'm hoping that it would work natively in the same way it works with the Teensy 4.0 and Audio Adapter.
(I'm choosing to use a Feather M4 instead of the Teensy 4.0 because the TinyUSB Library works with the Feather M4).
- If PJRC's Audio Library works, would I also be able to simultaneously run TinyUSB and have the device be a Mass Storage Device?
The project is to be able to load new WAV files onto the board via the USB port plugged into a computer instead of needing to remove the SD Card every time I need to swap out WAV files.
Thanks for the time and help!
Links to the libraries and products I am referencing:
PJRC's Audio Library (Adafruit's Fork): https://github.com/adafruit/Audio
Feather M4: https://www.adafruit.com/product/3857
Music Maker Feather Wing: https://www.adafruit.com/product/3357
Teensy 4.0: https://www.pjrc.com/store/teensy40.html
Audio Adapter: https://www.pjrc.com/store/teensy3_audio.html
TinyUSB Library: https://github.com/adafruit/Adafruit_TinyUSB_Arduino
light crag
I dumpster dived again
Now a stereo system I want to try to fix this hmm
I tried the amp seems to come out no sound haven't tried the other things yet
Someone wanna help me restore this things
@glacial spruce that radio with brokeb swith above i skipped that i feel like it was not worth it but do you think this is worth it
glacial spruce
The main amplifier looks pretty straightforward (transformer power supply, big heat sink). The control gear looks pretty intricate, but you may be able to get away with not using it if it doesn't work.
For "no sound", the fix is often pretty easy. Make sure the speakers and wires are good, and check any fuses. If all that checks out, switch the amplifier to one of the external inputs and connect it to a source. Make sure the speakers are selected, tape loop is off, etc.
If still no sound, try injecting a signal at the input stage of the amplifier.
pallid latch
Clearly, you came here for some.... sound advice.
light crag
it had one bad fuse at the transfiormer othervise everything looks good
When I touch the volume button I hear spark sound I think it's a bad connection in the volume knob I hear audio but really low
glacial spruce
That probably means the amplifier itself is fine, but the switching circuitry has a bad connection, is misconfigured, or damaged.
light crag
Oh yeah makes sense
I know the volume knob on my headphones had the same problem I got new headphones
So yeah I should look at the potentiometer
Spraying some break cleaner on it did help a bit no spark sound still low and a hiss hmm like
Maybe it was some dust in it but what cause the low volume
Putting it on max volume is kinda the normal volume
Somewhere it's a bad connection or something is shorted out
final yoke
I've read somewhere break cleaner is risky for carbon trace potentiometers
It said it might remove carbon layer
If max is normal value I don't think it's just a pot issue (idk what it is but we had similar issue and we send amps to the repair place)
light crag
Well it was actually not break cleaner it was electronics cleaner sorry
final yoke
Just giving heads up :)
light crag
I found mine in dumpster room I will fix this
Low volume and hmm sound what is the problem
final yoke
Uhm in our case outputs were shorted but ours was a very niche problem and purely from user error
light crag
Ok
light crag
I need help
I see no output caps or relays
Is it the input
glacial spruce
It's probably mechanical switching (if any) instead of relays. Probably BTL amplifiers.
light crag
It has 1 relay down there but I think it's for the psu and it clicks when I plug in
This thing is mostly transistor based
Well yeah you are probably right about btl amplifier
If you wonder what amplifier it is it's a Kenwood R-24XL
glacial spruce
Ah, those do look like output transistors. Perhaps the chips do all the input/switching.
light crag
Yeah...
I do not think they are bad they are not open
All the other thing work I tested them now except the cassette player I don't have cassettes
light crag
No hmmm sound anymore it was a ground loop
But still that it's low
light crag
I'm so dumb
You need adapter
i guess i got a free amp who just needed a fuse and a cord replacement
glacial spruce
Not bad.
Most amps call that a "tape loop" (you might remember I referred to that) and have a facility to switch around it if it isn't used. Apparently that particular amp calls it "adapter" and there's no switching facility, so you have to connect it yourself.
light crag
I really love playing around with old audio stuff now I got a a early transistor radio i don't know what it's from but somewhere 70s should I replace the caps it's rubycon caps
It still works but I restore it
alpine cloud
@light crag In general the electrolytic caps tend to "dry out" and decrease in value over time. If replacing them be sure to observe the voltage rating. The smaller ceramic or Mylar caps probably should left as is unless there is a problem.
glacial spruce
Old paper caps can get leaky as the paper degrades, but they're less common in 70s vintage gear than earlier stuff.
alpine cloud
Old paper caps is why I haven't fired up my 1946 RCA 5" TV, I'm afraid of a confetti explosion ๐
glacial spruce
The paper ones don't usually explode, they just leak electrically, propagating voltage to places where it shouldn't be. The electrolytics are the ones that usually pop.
That TV sounds like a neat unit, however.
Do you have service info for it?
alpine cloud
Grandpa won it right after WWII, all that was broadcast were fights on Friday night
glacial spruce
Oh, it has family history too? That's even better!
alpine cloud
I believe RCA has (or at least did have) pretty good archives on all the chassis, it's been awhile, the schematic may be glued inside
glacial spruce
I have several shelf inches of Sams Photofacts on early TVs, I can check if I have anything for it if you like.
alpine cloud
the last time it was fired up (80's?) the crt looked very soft
Sams!!!! I hadn't heard that in a while
glacial spruce
Soft as in soft focus, picture blooming, that sort of thing?
alpine cloud
no blooming as I recall, may not be crt, could be i just need to replace all the caps
glacial spruce
The CRT is likely fine. The parts that usually go are the aforementioned paper and electrolytic capacitors, and carbon composition resistors that have changed value.
alpine cloud
and even if i fire it up, i'll need to add a VBS input...
glacial spruce
You can always use something like an old VCR as an RF modulator to give it a signal.
alpine cloud
ahh, one day I'll retire ๐
alpine cloud
is it a line powered or battery powered unit?
dull basalt
Sam's Laser FAQ (https://repairfaq.org/) has good information on bringing up equipment that likely has a fault in it.
glacial spruce
There are probably some ceramic and mica capacitors in it, but those will likely be fine.
I'm looking at the 10/1946 Sams index, and it shows 9 different RCA chassis, but they may all be radios.
alpine cloud
@glacial spruce I'd have to dig through the garage to gain access but maybe I'll ping you one day to check your archive
dull basalt
'boat anchor' is a good search term in connection with antique electronics.
alpine cloud
lol, just can't part with Grandpa's TV...
light crag
Idk if that's some old glue or a capacitor leak but Imma replace all of them anyway
alpine cloud
@dull basalt, not the exact model but very similar vintage
only so much RAM above my shoulders, trying to keep up with SMPTE ST 2110, the pentodes have to go...
@light crag probably glue, but it may become conductive with age
glacial spruce
Heh, I'm working up a pentode design at the moment (the triode approach didn't have enough gain)
I agree, probably glue. That style of capacitor, when they leak, usually leak from the end with the leads.
dull basalt
TT-5 also turns out to be a Transmission Tube manual in that Boat Anchor Manual Archive, under RCA ;)
Nice long PDF document from RCA on transmitter tubes.
glacial spruce
It's interesting just thumbing through the old schematics. Before there were tubes made for horizontal output service, they'd sometimes parallel two tubes to get enough current. I found a really cute tube pocket radio made with soldered-in subminiature tubes.
alpine cloud
also buried out there I have an old o'scope that uses "transistor sized" tubes, circa 1962 i think
light crag
I really like this 70s radio it's interesting
dull basalt
I had a tube type shortwave radio receiver with ah maybe half a dozen miniature receiving tubes in it. Just the chassis; I think the dial string and pulley was intact, but no dial scale to see where you were tuning to. Not very big - 12" max maybe 13" on the largest dimension.
I think I enjoyed that radio more, in some ways, than a complete one, because it still worked, and when I'd hear a foreign country's radio program, it was impressive I'd found it without a dial to steer by. ;)
Back then I didn't know it would feel like the same-old-same-old after a while. Still a new experience for me.
Come to think of it with the .. world thing going on right now .. might be interesting to listen on shortwave for a while.
glacial spruce
Ah, the Nuvistor tubes. Tektronix and a few other companies used them for a while in o'scopes, they gave high input impedance and resistance to overloads.
Amusingly, I have been listening to shortwave recently. I had a nice spool of insulated Copperweld wire, so I strung it out through some trees as an antenna. Works reasonably well.
glacial spruce
They still make those sets http://www.lectron.de but the factory is currently closed due to the pandemic.
alpine cloud
have you considered implementing an 1802 in triodes ? ๐
glacial spruce
Briefly (I have a fondness for the oddball 1802), but that would be a lot of triodes. I did make a flip-flop, however, which could be a 1-bit memory.
alpine cloud
it's a start! 10,000 sq feet later....
glacial spruce
I think we're going to need a bigger boat power supply.
alpine cloud
on my Elf I added TWO 4k memory cards, the house lights dimmed when I fired it up...
glacial spruce
The kind with rows of chips, where each row has a 7805 1-amp regulator to power it?
I have a way to go before this 1802 breadboard has as much capability as an Elf.
alpine cloud
as i recall just one 7805 per board - with a big heat sink (lights dimmed cuz it was a 1912 house i was living in at the time)
glacial spruce
The whopping 16k of add-on memory in mine eats a lot of power (I think there are 4 regulators on each 4k card)
alpine cloud
did you store programs on cassette tape?
the Elf used FSK to store / retrieve data from tape
glacial spruce
Yeah, I stored programs on cassettes. I still have the cassettes, but they're probably not pristine after all this time. I'm thinking of digitizing them and writing a Python program to try to demodulate the signal.
I think they were the horrible old "Kansas City" standard which unwisely used harmonically related frequencies, so distortion easily caused misreads.
The cassette modem I used was bigger than the entire computer.
alpine cloud
I wish I had stuck with computers but at the time they didn't seem more than a curiosity, so i went into something "real" - analog video - who knew it would then turn full circle, broadcast video devices are computers now
for a while there we actually fixed to the component level, nowadays you swap boards like they were 6AU6's ๐
pallid latch
Yeah, it's un-reel how much video has changed
alpine cloud
literally tubes to BGA's in my working lifetime
pallid latch
Yah, my wife and a bunch of her professional colleagues get to deal with the aftermath of all this.
And by that, I mean, obscure formats with a limited number of remaining functional players
alpine cloud
I'm an RS170A expert - that and a token get me a ride on the subway these days ๐
reminds me of NASA casting about to get programmers to talk to the Voyagers launched in the 70's
no Python there...
anyway, the Mrs is glaring - off to work - have fun everybody!
light crag
I tried to replace all caps now it won't work
light crag
Maybe I connected something wrong
glacial spruce
Good thing you have a "before" picture to reference
light crag
I forgot to take :/
glacial spruce
Did you? https://cdn.discordapp.com/attachments/422210663507558401/713820567396024440/20200523_202714.jpg
jagged yew
Hello there, I'm looking for an audio designer to design a wireless BT microphone with realtime DSP for a project
solemn flint
@jagged yew It may help if you indicate where on the spectrum you fall between "I want to pay someone $10 to design me a custom mic so I don't have to buy one in the store for $20, because of course it's super-easy" and something more like "I represent a serious company and we are looking to engage a professional audio electrical engineer for a nine-month product-development contract with a two-comma budget". ๐
jagged yew
I'm looking for a MVP, budget is about 1500 USD (startup). I'm looking at some options and help
solemn flint
Great, thanks for the clarification. ๐
jagged yew
Is something like this MIC -> DSP(REALTIME FILTERING, LOWPASS; HIGHPASS; BANDPASS) -> OUTPUT -> BT AND JACK
I was using an ESP32 with the SGTL5000 codec, but the DSP part is hard. Sadly, esp32 doen't have the teensy audio library, so I'm looking to that option too
ebon bobcat
Im trying to make an audio player with an sd card and an arduino, will any npn transistor work?, the tutorial says I need BC 546b but I have some random npns lying around
solemn flint
You probably should link to the tutorial you're following, since transistors could be used for a lot of different things.
green zodiac
Hi everyone. I was wondering if anyone knew how many sounds the PyPortal could play simultaneously?
Is it polyphonic at all?
versed torrent
That unit doesn't have any sound synthesis hardware. The speaker and audio output are just driven by the A0 pin off the microprocessor. The microprocessor has a 12 bit DAC connected to that pin. In software, you can compute as many voices as you can, limited only by the amount of CPU power, and the complexity of the synthesis algo. you choose.
alpine dirge
Hi all. I'm working on a little project that involves a 2.1 speaker setup. I'm using the TPA2012 (https://www.adafruit.com/product/1552) to drive my L/R channels via a 5V USB hub. I'm having a weird issue though. When I turn the volume up on the input, the left channel pops and shuts off while the right channel remains on. If I set the dip switches down to 6DB, I can max out the volume on the input, but I know I can get more power thru these speakers since they're being driven at much higher volume @ 12DB. Is the cutout maybe an issue with power delivery? Because it consistently occurs during strong base hits
I can't find any documentation of this 1 channel shutoff being a safety feature on the data sheets or on the learning page for the product
alpine cloud
@alpine dirge have you swapped the speakers to see if the issue follows the channel or the speaker?
alpine dirge
Ooo, I actually hadn't thought to try that yet.
alpine cloud
dunno which outcome is worse, but at least you'll know better where to look ๐
alpine dirge
I don't think it's anything to do with the speakers themselves though. They were running just fine with a PAM8403 amp
alpine cloud
might be worth a try just to confirm it's module based but i agree with the thinking
alpine dirge
Wishing I had breadboarded it out first rn. Because I'm really not trying to desolder this circuit again too ๐
alpine dirge
Nope. Not using the shutdown pins at all.
alpine cloud
shouldn't need to, just thinking...
alpine dirge
I tried adding a 100uF electrolytic cap to VCC and GND, which I thought MIGHT have made a slight difference?
alpine cloud
probably doesn't hurt just on general principles. i'd expect both channels to behave the same way if it was the chip
alpine dirge
Thats what was throwing me off
It's ONLY the left channel that shuts off at higher volume
the right channel stays on, and I can even crank the gain all the way up to the 24DB max and it keeps on playing
Granted, it sounds like trash, but it works
alpine cloud
never do get quite the hifi you'd like with these in my experience
alpine dirge
Yeah, I'm just completely space constrained which is why I've been sticking to Class D amps
alpine cloud
you soldered the speaker rather that using screw terms?
alpine dirge
Yeah
alpine cloud
no tin whiskers between the pads?
alpine dirge
I'll double check with beeper mode, but I don't think so
alpine cloud
use a higher range and see if both read the same
alpine dirge
My solder work looks like trash, but no whiskers.
alpine cloud
is the left speaker chassis grounded? looks like this wants to run full differential
alpine dirge
Sorry, I donโt quite understand the question? I know this amp is outputting a differential signal and that I canโt tie the L/R โgndโ outputs together
And the input also wants a differential but Iโm inputting from a standard 3.5mm jack with a common ground
alpine cloud
just wondered if 1 speaker is touching ground and the other isn't
alpine dirge
So I did like the learn page suggested and tied my L/R minuses together to the input ground
alpine cloud
i don't see anything obviously wrong, all sounds good (no pun intended), just thinking out loud...
if the input was the issue both channels should pop
alpine dirge
I was worried about the input too since Iโm also splitting the input into another L/R set of wires mixed to mono with 2 4.7k resistors for one of these: https://www.adafruit.com/product/2130
alpine cloud
i think you need to heat up the iron ๐
alpine dirge
PAM8302. But I disconnected one of the lines cause I thought maybe the connection was biasing one of the channels to ground more strongly?
alpine cloud
to troubleshoot variables need to be removed
alpine dirge
Didnโt change anything tho far as I could tell
alpine cloud
in theory it sounds good but by removing all but the input >> TPA >> speakers will help isolate the problem
then if that works, add things back
was working with a guy today, swore my product wasn't working - turns out his commercial 3.5mm jack was bad...
alpine dirge
Ooof. If it's my input, I'm screwed bc I broke it open to solder directly to pads instead of using a breakout plug
alpine cloud
how about routing a completely different source of audio into the module?
even mono to test
alpine cloud
then if it cranks left channel it's the input
alpine dirge
Ok, maybe not the smartest way to test my source, but thatโs still cutting out that way too.
alpine cloud
but right is OK with same setup?
alpine dirge
Yeah left plays up to the same point
alpine cloud
you mean left always drops out at a particular point in the file?
alpine dirge
Yeah, it cuts out passed a certain volume
alpine cloud
but it cuts out on any old audio file?
alpine dirge
Anything below that, they both play fine. After that point, only right channel will play until I reset
Yeah. Iโm using various streamed songs to test. Local files are the same. Itโs base hits that knock out the channel which is why I thought it was a power issue
alpine cloud
ok
then its either the TPA or possibly the speakers, at least it rules out your input as the problem
alpine dirge
:/ alright, I'll probably just have to take the L on this problem and not set the audio any higher
alpine cloud
let me know if you do find out what caused it - happy hacking!
alpine dirge
Thanks for the advice!
alpine cloud
no problem, a little bored in lock down ๐
green zodiac
That unit doesn't have any sound synthesis hardware. The speaker and audio output are just driven by the A0 pin off the microprocessor. The microprocessor has a 12 bit DAC connected to that pin. In software, you can compute as many voices as you can, limited only by the amount of CPU power, and the complexity of the synthesis algo. you choose.
@versed torrent ok, thank you very much for your reply!
spare nebula
Don't know if this's the right channel to post this, but I'm curious to hear this community's take on audio equipments
Particularly DAC/AMPs
Do they become gimmicks at some point, or justifiable part/measurement-wise for the exponential increase in price?
I tried asking in an audiophile community and most of them swear they can hear the differences between most DACs compared to one another
I can hear the differences between tubes and solid-state amps because they're somewhat fundementally different, but not one SS to another.
final yoke
Personally didn't tried tube amps but it makes sense they have different characteristics. I don't have many in depth knowledge on the topic (tube amps vs ss ones). Imo "audiophile" filled with bunch of nonsense and scam. Even big firms do this, too. Silver cables for mains, specific pattern etched on capacitor electrodes... Sure, maybe %1 of the population can hear between good amplifier, and best amplifier (not fake improvements like silver mains cable). Problem is community is significantly bigger than 1%, and convoluted with false information. At least this os my logical take on the subject
@spare nebula
Some people may disagree but it kinda have the "apple problem". Apple acts like their audience is really rich people and people see Apple as luxury and want it, and when they have the luxury they act like it all matters. (I know this is kind of controversial to say but I do think like that)
Also placebo effect comes into play too. With the money they spend on luxury audio (actually there is no luxury about it), they feel/act like there is a difference.
spare nebula
Hey thanks @final yoke for spending time writing this! I'm generally confused as what some claim as "luxury," or "high-end" audio sources. To me it just doesn't make sense to spend hundreds or thousands of dollars for something that does the exact same thing as, let's say, a $100 DAC (which works perfectly fine). I'm mostly curious how people can claim that one device, used solely to convert a digital signal to an analog one, can sound "rich" compared to a lesser priced product
Because claiming there's some sort of sound signature alteration from a DAC means that... it's not doing its job properly?
And oh god all the lingos
glacial spruce
While there are some things that have an audible effect and therefore matter, a lot of things don't.
clear dove
Sound: https://voca.ro/cEwnxi2PtA2
Hello, so I have a hyperX cloud alpha headset and whenever I plug it in to my PC and try to record audio or voice chat there is a high pitched audio whine in the background. This still persists even if I unplug the microphone and hit record. As long as the headset is plugged in it makes that noise. I dont have this problem when I connect my usb-c earbuds. Anyone know what to do?
glacial spruce
Hmm, could be feedback (have you tried turning down your speaker) or a failing battery causing power supply whistle, I suppose.
clear dove
@glacial spruce fixed it by using my audo jack to USB adapter
apparently its a problem with DACS and RTX GPU's
versed torrent
@spare nebula - I heartily reccomend https://www.youtube.com/watch?v=BYTlN6wjcvQ - a great watch about Audio myths debunked. This is Ethan Wiener at the Audio Engineering Society confernce.... this is engineering and science by professionals.
dull basalt
Question regards Neotrellis m4 express board JST connector, I had attempted to hook up Adafruit 3.7w audio amplifier (MAXMAX98306) in order to avoid add write some code for since I am a plug and play person. The result was not working successfully. What are the requirement for me to set up from the board to speaker output from JST connector ( not powered speaker to connect audio jack that is already on the board)?
spare nebula
@versed torrent will watch tonight. Thanks for sharing this!
versed torrent
also - this is a sort of summary web page he has: https://www.youraudiosolutions.com/interview-articles/ethan-winer-busting-audio-myths-and-why-dave-pensado-was-tricked
but the video is great
pallid latch
Some.... sound advice either way
violet pagoda
???
teal burrow
i am audio-ignorant, but ran into an issue in my work that I need to figure out how to get around. We use a SIP paging adapter, http://files.cyberdata.net/assets/011233/011233_SIP_Paging_Adapter.pdf, at work for paging, and it has worked fine until someone moved it. Now we can't get it to work through our amp and speaker setup, and I cannot find it on the network when connected (multi-subnet network, a byzantine nightmare and no access to firewall config). The device features a little reset-like button that will announce the current IP over the speakers -- a catch-22 for us. ๐ฆ
It features an "input for balanced 600 Ohm 5VPP signal". How can I hack together an amp that would allow me to run this audio through a cheap internal computer speaker for us to just hear the IP announcement?
*output for 600 Ohm 5VPP signal
violet pagoda
mmmm
teal burrow
I am no good on the audio and paging system, supervisor just knows that I like tinkering with electronics...
teal burrow
lol... white rum or barrelled?
or maybe having a daring Friday with some spiced rum? ๐
violet pagoda
just use a simple computer setup --- local desktop speakers -- you can monitor all events there --- if all is good then allow out with a simple switch to main big boom speakers
teal burrow
i'm just ignorant, will the speakers accept the "600 Ohm 5VPP signal" without being modified?
violet pagoda
hmm i guess so--- just dump the audio to a monitor computer in office then have a switch to go to store speakers--keep it simple
preview all audio on private computer in office -- then can have simple switch to go LIVE to store speakers
teal burrow
i got you there, but I can't even figure out if it is on the network properly because I can't find it in the 255.0.0.0 network lol. I thought I needed a 600 Ohm transformer to get the audio to the right level for the speakers to use?
violet pagoda
there should be some network discovery tools -- to search net , Khali linux may have a tool , find all dev on local
something LINUX flavored
teal burrow
already used my kali, but the 16 million possible IPs in the /8 network takes a while, no matter what -- and there is a network discovery tool from the manufacturer of the adapater, but it doesn't find it when at the shop (where all the amplifier and speakers are), but when I bring it home it finds it fine -- but I can't test it ๐ฆ
i can't test it at home
violet pagoda
ohh you have some -- overly complex router at work?
teal burrow
Yes, it is a multi-site business with places in a few different towns\cities -- they had it all configured back in the early 1990's and although equipment has been updated, the network topology has not
I might try setting a static IP and taking it back with me, but that is dicey when I don't have access to the firewall config to ensure a duplicate IP won't be created
violet pagoda
well need to sit with SYS ADMIN and show what you want to do -- and lock in your device MAC address
teal burrow
I agree, the network needs work, but we use a managed service provider and it is difficult to convey the requirements sufficiently, even more so now that we never see any admins on-site since hte lockdown
Thanks for the brainstorming session!
violet pagoda
on a home net is easy
teal burrow
yes, I can see network connectivity is up, but I can't see if the adapter is working because I cannot hear anything out of it -- I can call it from my soft-phone and interact with the SIP system, but I am unsure if the signal is getting into the adapter to be pushed out over the speakers. For all I know, someone could've put 120V AC across the inputs and burned up the audio circuitry, and I am working on a brick
*outputs -- not inputs
violet pagoda
need to grab the box and shake it - maybe its SQUIRRELS
pearl gazelle
@teal burrow that document shows a standard RCA line out. I would expect that to be able to feed any consumer audio gear
teal burrow
@pearl gazelle thanks for pointing this out, audio has never been a strong point for me and I am very dumb when it comes to it. I will see if I can connect it to a home receiver and see what I get out of it
my supervisor kept pointing to the interface pins because that is what is connected to the paging system -- so I never looked elsewhere
@pearl gazelle I feel a super dummy on this, that worked and I heard the correct IP. Will take my receiver to work tomorrow to test there. Thanks for pointing that out
versed hatch
I am trying to use midi using this library: https://github.com/FortySevenEffects/arduino and I was wondering how does the serial connection work? I am assuming it is TWI serial and not an SPI interface. Could I connect multiple midi devices in parrallel? Thank you again for any assistance you guys/gals have been very helpful!
glacial spruce
MIDI is neither TWI/I2C nor SPI: it's asynchronous serial.
versed hatch
I am a bit confused on what pins I should use for asynchronous serial. Does it matter? I am not seeing a whole lot in the data sheets
glacial spruce
There are two basic choices: hardware serial and software serial. There are specific pins that support hardware serial, there is more flexibility with software serial, but it can have timing issues.
versed hatch
What would I look for in the atmega32u4 to find hardware serial pins? Is it any pwm pin?
glacial spruce
The ATmega32U4 has one UART, on pins PD2 (RXD1) and PD3 (TXD1)
versed hatch
thank you!!
cosmic warren
ay can anyone help me out
can i replace a buzzer with something that connects to a bluetooth speaker and outputs audio to the bluetooth speaker
so instead of the sound going through a buzzer, it goes through a bluetooth speaker
glacial spruce
That's tricky: a buzzer is pretty simply, just send it voltage and it makes a sound. For a Bluetooth speaker, you'd have to be able to pair with the speaker and then generate a sound file and transmit it to the speaker to play. Not impossible, but somewhat involved.
shut bough
hello! is my question in #help-with-projects more suited for this channel? ๐
outer gate
I got a bit of a long one guys, sorry haha. So Iโm implementing a headphone driver into one of my IOT projects and need volume control on it. Easiest solution would be to plop a potentiometer on the signal inputs of the amp and call it a day, but for this given project it would be preferred to have button based volume control. So like the one on your iPhone. The amp of choice has i2c inputs for digital volume control, but I have no idea of how to implement this. Would you guys suggest something like a digital potentiometer chip? But how would that correlate with use with tactile buttons for volume up and down? Any help is greatly appreciated. Go ahead and ping me since I might not get notified if you respond
alpine cloud
@outer gate do you have a link to the i2c amp you mentioned?
outer gate
@alpine cloud it is the tpa6130a2 I believe. I can upload the data sheet if youโd like
alpine cloud
found it...
I2C is a fairly easy to implement protocol, most mcu's support it, why not go all digital ๐
outer gate
I still need a high quality class AB amplifier and this seems to work perfectly. Audio is coming from a whole different source so I am trying to figure out how to control the i2c with buttons
alpine cloud
since it's iot i assume you are using some sort of mcu, an esp maybe?
outer gate
Itโs the esp32 from what I remember. I kinda scrapped the project awhile back now Iโm trying to finish it
alpine cloud
that supports i2c, you'd need some buttons, some code and send the correct up or down command to the amp
outer gate
That seems doable. Iโll see if I can read more about the protocol and let you know if I get it working. Cheers mate
alpine cloud
for your reading enjoyment, happy hacking! https://randomnerdtutorials.com/esp32-i2c-communication-arduino-ide/
outer gate
Awesome
stable peak
I need to pick up the volume of a audio signal using a small microphone(for audio visualization) and a Arduino but what I am wondering is do I need a audio amplifier so the Arduino can pick up the output signal.
glacial spruce
You probably do need an amplifier, and possibly a peak/envelope detector as well, depending on what you're doing. Most microphones (other than crystal microphones) don't generate sufficient voltage for an Arduino to digitize effectively.
stable peak
Can I just use a op amp
glacial spruce
An op amp would do a good job, yes.
stable peak
Ok thanks
scenic axle
@glacial spruce Do you happen to know anything about using with the MAX98357? There's someone on the forums who can't get theirs to work with a Raspberry Pi, and my useful knowledge on the subject ended after I verified it was plugged in correctly
glacial spruce
I've played with some of the class D amplifier chips, but I don't know a whole lot about I2S in particular.
scenic axle
Ah, ok
glacial spruce
Still, what's the forum link, I can give it a read and see if anything catches my eye
scenic axle
Sure, here ya go https://forums.adafruit.com/viewtopic.php?f=50&t=166526
glacial spruce
Wow, the install script is bewildering. It may be that it won't work without a reboot, if the existing driver "steals" the sound stream, but I really don't know.
scenic axle
Ah, yeah that could be it
whole ferry
hey
bleak palm
Hey everyone! Hope you're all well! Is there an easy way to hook up a Teensy Audio Shield https://www.pjrc.com/store/teensy3_audio.html to an Adafruit Grand Central M4 Express https://www.adafruit.com/product/4064 ? How are the chances that it would just work out of the box with the Audio library port? https://github.com/adafruit/Audio The Audio shield is pictured in the github README but chances are that's just carried over with the fork from PJRC. Has anyone tried this?
whole ferry
hey
bleak palm
Update on our project - we haven't gotten it to work yet, although we're pretty positive on the cable / connection side. I wonder how other makers use the Grand Central for Audio projects? Is there a codec that's a better fit?
whole ferry
hey
glacial spruce
<@&327289013561982976>
bleak palm
@glacial spruce thank you that took an unawaited turn ๐
fossil shale
on it...
fiery mauve
Not sure how active this is, or if this is the right channel, but I'm making an audio amp with some TDA2822L IC's that I salvaged, and I was wondering.. is it possible to combine multiple low powered amps in parallel or something to deliver more power to the speaker without it clipping?
or does it just not work that way
glacial spruce
In general, it does not work that way, but you may be able to use a bridged configuration to double the power with two amplifiers by putting one amplifier on each end of the speaker. There may be ways to do current sharing with resistors, but you'd probably have to modify the feedback networks to make that behave.
fiery mauve
yeah sounds like its more trouble than its worth. bridged mode is plenty loud for my application
vital birch
hi makers, I got few questions regarding the powering of the Audio FX board https://learn.adafruit.com/adafruit-audio-fx-sound-board/powering-it
I've set up couple of OGG sounds, renamed them correctly, it works right and plays the related sound when I plug a trigger pin to ground.
Until I try to use my phone 'adaptating' fast charger (9v 1.67a - 5v 2a), then the board acts weird and no sound are triggered anymore (except when the pin is already shorted when powering the board, that sound will play at start , stop when unplug the pin but no more sound will trigger after that)
Can it be powered with fast chargers or I should stick to regular ones?
whole ferry
hey
lucid oracle
I'm doing a second layout for a Bluetooth Audio Adapter. My first layout had hum on the audio line. I figured that was due to a ground loop. In my first design, I had a ground pour on both sides. I figured that might have had something to do with it. This time, I only have ground on one side (bottom polygon) and, by the looks of it, it's pretty big and uninterrupted. Anyone have any tips on laying out boards for audio? The highlighted polygon (bottom) is the ground layer. Components are on top.
Without the ratsnest.
This is the previous design with ground on both sides.
Top layer (components on top) ground pour on both sides (top and bottom).
Bottom layer. Ground pour on both sides (top and bottom).
Also, let me know if this should go in #help-with-hw-design instead. Thanks for the input.
Hopefully the 0.1 inch-spaced, 6 pin FTDI header will give you a good idea on size, but the new board is 57.2mm x 40.9mm and the old board was 36.8mm x 24.2mm.
glacial spruce
The ground on both sides will generally help (more shielding), but you want to be wary of ground loops (where the ground references of a signal disagree), ground current (where digital and analog signals share a ground), interruptions in the ground plane which steer current to where it can cause trouble), and coupling (capacitively or inductively adding noise to a signal).
lucid oracle
Okay. Based on that, I'm thinking my new design might be better then. It only has ground on one side, but it's pretty uninterrupted.
Ground plane
Power plane
charred tide
I need some advice from the tube guys over there. I'm designing a small amp for funsies and want to use a 3Q4 battery operated tube as output. The datasheet gives the internal resistance Ri (or impedance) as 10kohm for 90v but I want to use it at give or take 45v. This means Ri would be higher and I will have to choose another output transformer. So the question is, how do you calculate Ri/Impedance in regard to anode voltage?
glacial spruce
I would guess the plate resistance wouldn't vary a lot with supply voltage.
Might want to ask in #help-with-arduino instead of an audio channel.
quiet rover
LOL audio and arduino look similar to me, sorry
cedar plinth
@lucid oracle Ground on both sides is fine, but you need to add some GND vias to stitch both sides together, so the signals on both ground pours are identical.
west hornet
How to make. A module diy that will help to output audio from raspberri pi zerow
Helo
glacial spruce
There's some information here on how to get an audio output from a Pi Zero W. https://learn.adafruit.com/introducing-the-raspberry-pi-zero/audio-outputs
lucid oracle
@cedar plinth @glacial spruce thanks for the tips folks. I'll give both of those things a try.
bleak palm
@lucid oracle here is a very good article on the topic https://www.analog.com/en/analog-dialogue/articles/staying-well-grounded.html
haughty comet
Ey so Iโm having trouble getting a voice amp working for my new face mask, keep getting this horrid noise when taking the mic preamp output and putting it on the speaker amp output, I think it has to do with them sharing the same power supply, and ideas? Iโm using a max4466 mic and pam8302 breakout
glacial spruce
What sort of noise? Could be acoustical feedback or electrical feedback.
haughty comet
Kinda like a sawtooth noise, I have a scope and looked at the input stage, itโs like the mic is dropping out, hereโs a crude drawing of the waveform
I can get a legit image in about... 5 hours
alpine cloud
@haughty comet It will be helpful to have a diagram of how the two are wired, in general they seem compatible with each other...
haughty comet
Thatโs it pretty much, speaker is just 4 ohms on the output
Iโm using 3.3v, but I also tried 5v and still get the same issue
glacial spruce
Maybe try powering them from different power supplies as a test. If there is still a problem, it's probably not coupling through the power supply. If the problem goes away, it probably is coupling through the power supply. Knowing the results of that test will help decide what to do to fix it.
alpine cloud
@haughty comet take a look at https://www.instructables.com/id/PAM8403-6W-STEREO-AMPLIFIER-TUTORIAL/ and specifically "USE CO-AXIAL CABLES <for...> AUDIO INPUT. FAILING TO DO SO WILL RESULT IN HORRIBLE RF INTERFERENCE AND BAAAD AUDIO OUTPUT." At a minimum I'd recommend connecting mic gnd to the PAM8403 analog ground
haughty comet
Iโll try it but ideally I get it to work on a single 18650, itโd be weird if the coax works, or if the breadboard is really picking up that much rf
glacial spruce
I think that PAM chip is a "class D" amplifier, which produces a lot of high frequency electrical noise as it's operating, due to how it works.
alpine cloud
@haughty comet any luck?
haughty comet
Not yet, was working on something else, but I got an hour left in the night to give a few things a shot
welp, separate power supplies worked, quite a bit of distortion however. Also slightly complicates things cause I wanted them working off a single source. meh, I can get some boost regulators and have them run at 5v seperately
alpine cloud
did you try connecting the analog ground?
haughty comet
all the grounds on the PAM breakout are tied together, same with the mic
alpine cloud
another thing to try is 100uF and a 10 - 100nF right at DC input - or an LM386 ๐
haughty comet
I actually tried a sparkfun LM386 breakout as a buffer, same problem. I've tried a 220uF in line with the input but not as a buffer, could try that
alpine cloud
same waveform on the analog 386?
haughty comet
same noise, didnt compare waveforms
alpine cloud
sort of leaves out the class D amp as the noise source
haughty comet
interesting, the cap heavily muffles the output, but that would make sense, its still making the noise though
alpine cloud
a low pass filter maybe, a 2.2K in series with a 220nF to ground
the big cap in series might muffle the low end some but wouldn't help if the noise is high freq
alpine cloud
gain is too high, it's oscillating on the high end
haughty comet
Probes right on the mic output to amp input line
Only happens when connected, the mic output looks normal when the mic isnโt connected to the amp input
alpine cloud
how far is the mic from the PAM, a few inches?
haughty comet
About... 1.5
alpine cloud
should work with coat hanger wire from there...
haughty comet
Thatโs the crime scene
alpine cloud
is there a trace on the pam from dc to analog ground?
looking at it maybe it isn't hifi but should be usable...
alpine cloud
and a small ceramic right at dc in didn't help at all?
haughty comet
You mean the power in for the amp or audio signal in?
haughty comet
I put a 104 cap on the dc in for the amp, and the mic, no dice
Thereโs also a 220uF on the main rail for both
alpine cloud
think i'm gonna cross PAMs off my list if i need an audio amp in a project ๐
haughty comet
Lol
alpine cloud
but strange the 386 wasn't happy either
haughty comet
I had the same problem with a semeco amp.
alpine cloud
but ideally you want to run off an 18650...
haughty comet
yeah, and the whole thing would be compact
alpine cloud
you have the two speaker grounds connected together?
haughty comet
there is this board i really wanted since it looked perfect, but it'd take a month and isnt on prime
the speakers are just working off the right channel and tied in series
haughty comet
I found that putting a 200 ohm resistor in line with the speakers did get rid of the noise, but the mic was too dim
Idk, could try it
nope. both speakers attached doesn't help
alpine cloud
and if you hook the mic to something else it sounds ok?
i've built 386's on breadboards and a setup like that worked, just wondering what else it could be
haughty comet
only by looking at the mic output i can tell it's fine, or putting a speaker directly on the output with a resistor in line to protect it can I tell it works
unfortunately im short stocked on ready-working amps lol
alpine cloud
lol
haughty comet
Now, the semico amp, it was from a crappy promotional speaker that took an aux input, that works fine with the aux signal.
Every attempt at putting a mic on the output with the same power supply caused the same issue
alpine cloud
cheap audio transformer laying around? like from an old pocket radio
just grasping at straws now...
haughty comet
I have tried looking for a common mode choke, I know I salvaged one, I just can't find it
alpine cloud
maybe the dc bias is bad between those two modules but then the cap in series shoulda helped...
and that board has ac coupling right at the input doesn't it?
haughty comet
I found an ac isolation coil, gonna try that
still made noise, but it was weird and different
oooo, I think I got it
had to put a 4.7k resistor in line with the coild so it wasn't a direct short
alpine cloud
and now it sounds reasonable?
haughty comet
crisp but a tad of distortion
alpine cloud
so it's an impedance mismatch between that mic and that amp
a 10K pot from mic to ground, tap to amp in ?
haughty comet
welp, slightly new problem, it's too quiet, I think the coupling transformer is originally meant to isolate mains, probably doesn't have enough turns to properly couple the signal
alpine cloud
yeah i'm thinking an 8 to 1000 ohm type of audio transformer, the pot trick didn't work?
haughty comet
I swapped out some resistors till I started noticing the audio quality decline, it started getting too quiet to be functional
alpine cloud
i looked at links earlier, that mic was spec'ed by the adafruit pam8302
haughty comet
sadly the instructables article doesn't callout a specific mic to use
alpine cloud
and those small cylinder mics are all about the same...
is there an amp on your mic board?
alpine cloud
ok, left with gremlins as only rational explanation
haughty comet
I'mma try some 600ohm transformers, not ideal cause they're still rather large. I still don't get what's up if this circuit was supposed to work long ago
lucid oracle
@lucid oracle here is a very good article on the topic https://www.analog.com/en/analog-dialogue/articles/staying-well-grounded.html
@bleak palm Thank you. I'll dig in.
bleak palm
@lucid oracle yes we also try to get it right as best we can .. no easy feat
lucid oracle
I think I have some Bluetooth audio figured out. Itโs streaming wirelessly from my laptop to the Bluetooth module, then my Bluetooth module connects to my car using an Aux cable. Some hum. A bit of noise at some frequencies with some clipping.
Definitely way better than last time. This is going to be tricky to put in my Smartwatch. My watch doesnโt have a dedicated ground plane like this little module does.
It might be useful to move the aux input from that side of the Bluetooth module. I forgot I needed to clear the antenna area of any other metal object.
glacial spruce
Not sure what you mean by "dedicated ground", but maybe a zero volt reference (there ought to be one somewhere), an antenna reference (counterpoise), or a pin for one of these?
lucid oracle
I meant โdedicated ground plane.โ Sorry, I forgot the last word in that phrase.
violet pagoda
interesting paper - Staying Well Grounded
untold plinth
Hi all, I've been messing around with a wemos d1 mini running micropython trying to play simple tunes with a passive speaker and PWM
its working pretty well, except when i try to play a rest note, with a frequency of 0, it plays for much longer than intended and seems to skip some of the next notes
is therew another way i can stop the speaker from producing sound that i have missed?
glacial spruce
May have to turn off the PWM (or set it to 0% duty cycle or something: I don't remember what methods the Micropython class offers), and do the delay manually.
untold plinth
yep, turns out duty was what I wanted
I was changing the frequency which in hindsight of course that didnt work
thanks!
azure carbon
Hi! Can someone suggest an i2s stereo input/output codec which can do atleast 16-bit 48k (24-bit 96k would be a nice-to-have) which comes in a DIP formfactor? Most stuff I found is SMT, like https://www.ti.com/lit/ds/slas533b/slas533b.pdf
solemn flint
That's a really tough requirement. All of the DIP-package codecs on Digi-Key seem to be marked as "obsolete", and I don't see any with I2S among the ones left in stock.
You'll probably want to aim for finding a surface-mount part with a breakout board.
azure carbon
@solemn flint what about a separate ADC + DAC combo?
Alternatively, does someone make a cheap "clamp" of sorts, for solderless use of SMD parts on a breadboard? I'd imagine it'd look like an IC socket except weirder.
normal dawn
SMT breakout board is your best bet
azure carbon
๐
Alrighty then! Any cheap 2-in-2-out i2s breakout boards I should look at? ๐
The PCM3060 does look nice!
glacial spruce
There are SMD clamps, but they're not cheap
azure carbon
How would something like https://h5.aliexpress.com/item/32978832170.html be, for the Pi to get audio capabilities? It seems to be a breakout board that comes with the like in and audio out jacks soldered in already.
scenic axle
@azure carbon So are you basically looking for a DAC? Because if you are, the AK4490 is a very good dac for the price and comes in the same package as the VS1003 you linked, and can do 32/768
azure carbon
@azure carbon So are you basically looking for a DAC? Because if you are, the AK4490 is a very good dac for the price and comes in the same package as the VS1003 you linked, and can do 32/768
@scenic axle
I need both an ADC and a DAC. This is for a guitar effects pedal.
scenic axle
ah
glacial spruce
The SGTL5000 used in the Teensy audio board might be another candidate.
azure carbon
Is it possible to interface the Teensy Audio Board directly with the Raspberry Pi? It seems to be capable of what I want anyway, and (relatively) easy to source.
Most dedicated sound cards for the Pi seem ridiculously expensive (when you compare it to the cost of a Pi Zero WH that I'd be using).
glacial spruce
I think it's an I2S interface, but I don't know offhand if the Pi supports that.
azure carbon
Are there any cheap i2s interfaces around which work out of the box on Linux mainline, no extra drivers required?
pale dome
i have this dev board with a digital microphone and right now I'm just trying to output volume via serial
ST-MEMS microphone (MP45DT02): digital using PDM protocol or analog when
using the low pass filter
this is what the manual says about the microphone
mental ruin
heya @glacial spruce you have a minute?
glacial spruce
Yeah, what's up?
mental ruin
I'm trying to match the tubes for my headphone amp and either
a> I'm very lucky and got a perfect match on the first try or
b> I'm measuring incorrectly
This is what I'm trying to do:
Match the tubes.These tubes do vary. Actually, quite a bit. This matters because the variation changes the gain of the amplifier. If you use two unmatched tubes, you could have gain thatโs off by a couple of dB on one side. Lower gain tubes also tend to have higher distortion, at least in our measurements.
To match tubes, measure the gain of each side with a 250mV RMS sine wave input at 1K. The amp will put out something like about 1V RMS. However, one channel might be 1.08V RMS, and the other one 0.92V RMS. Swap the tubes until theyโre closer (say, 1.08/1.02V RMS, or about 5%).
I'm using the signal generator and scope on my analog discovery 2 and once I figured out that I had to sync the two wave generators, the measurements in the scope are very close:
glacial spruce
Not bad!
mental ruin
though I'm not getting the gain I expect; one that that isn't clear to me is RMS vs. not in the signal generator
๐ค
glacial spruce
Not getting the gain you expect could be bias, plate voltage, or load resistance.
"not in the signal generator"? Huh?
mental ruin
sorry; the instructions say to feed a 1khz 250mV RMS sine wave through the amp. I've set the signal generator to 250mV which appears to be the amplitude which I didn't think was the same as RMS (which I only kinda understand)
basically, I don't know if I'm feeding the correct signal into the amp to compare it against the expected numbers.
which are 250mV RMS in, and ~1V RMS out
It does mention adjusting the plate load to get the output DC level to 7.5V so I suppose I should check that
glacial spruce
Looks like you have 250mV peak voltage, which is about 1.7 times the RMS voltage, so that's only about 150mV RMS.
However, if you're measuring peak voltage in and peak voltage out, it pretty much cancels out.
mental ruin
true
there ya go; upped to 425mV peak and I'm getting and AC RMS numbers much more like the suggested numbers. They are indeed close!
Thanks @glacial spruce ๐
I'm happy with those results
glacial spruce
Yeah, that's totally fine for matching, nice!
mental ruin
have you ever used sorbothane for isolation? I got some and it's very squishey and somewhat stickey.
glacial spruce
I got some half-spheres to isolate my first 3D printer. Not sure what they're made of, they're fairly squishy. For my second 3D printer, I went with rebond foam and a concrete paver.
For audio? I haven't done much other than have my speakers and my turntable not sharing the same furniture.
Ah, the hemispheres are apparently silicone.
They're sold for audio use, but they work fine for 3D printers.
mental ruin
fair enough
bright valve
Hi everyone. I'm trying to find any docs on synth programmers built with arduino but am running out of luck. Has anyone here tried anything like that, or have any good resources to get started?
(Sorry for cutting in on your conversation)
mental ruin
unfortunately my plate load isn't as great as I'm seeing the DC bias at ~ 8.75 as opposed to the ideal 7.5
glacial spruce
Like using an Arduino as a synthesizer, or using an Arduino to control a synth via MIDI, or something else?
mental ruin
no . worries! a> we were basically done and b> it's all good anyways
glacial spruce
The actual bias value isn't critical, I usually adjust bias by current (measuring the voltage drop across the plate resistor is one way).
The specs for a 6418 with 22.5 volts on the plate is 240ยตA quiescent current, but that amp uses it triode connected, so the plate current would be higher.
bright valve
I have a Jx-3p that can be programmed using a separate tool, I'm trying to build a replacement for that with arduino
glacial spruce
Hmm, usual bias is -1.2V, nowhere near 8.5, but perhaps that amp is running it at higher plate voltage
Still unclear on what you mean by "programmed" in this context. Like loading settings, or sending a sequence of notes? How does the tool normally connect to it?
glacial spruce
reads Hmm. Apparently 2 pins are power supplies, and it uses a proprietary protocol.
Ah, here's some useful stuff http://www.florian-anwander.de/roland_jx3p//jx3p_schem.htm
bright valve
Yes I saw that! Maybe custom pcb > arduino for this? Idk about the proprietary protocol but there are several mod packages out there for it so I feel like someone has figured it out
glacial spruce
The PG-200 schematic shows that there are only two data signals: busy and data. This page https://forum.arduino.cc/index.php?topic=572929.0 says they're 9-bit serial frames, but doesn't give a lot of data. If you have a PG-200 and an oscilloscope or logic analyzer, it should be easy enough to pick up the bit rate and the "start" message.
Yeah, people have figured it out (there are MIDI to PG-200 adapters available), but they don't seem to be interested in sharing the details. The processor interface is pretty trivial (a transistor and a few resistors for each signal).
I wouldn't start with a custom board, I'd just breadboard the drivers and see if the Arduino can send the messages (the forum thread above points out that the Arduino UART is capable of sending 9-bit signals)
mental ruin
@glacial spruce I may have mispoken; when I said "bias" I meant the DC offset voltage just before the output decoupling cap
bright valve
That's great advice to start on, thank you!
glacial spruce
Ah, protocol is described here https://www.xonik.no/mpg200/pg200, 9 bits, 31.25kHz.
bright valve
Oh great find!
mental ruin
oooh, fun project
bright valve
That last link is excellent
glacial spruce
Ah, so presumably the plate voltage at idle, which would be controlled by the plate supply, the plate resistance, and the grid bias. Given tube variations, the difference between 7.5 and 8.75 is pretty small (unless your plate supply is really low like 12V). That's the other main variation in tubes: one is gain, the other is bias. Many amplifiers offer the facility to adjust the grid bias to get the desired idle plate current. The DC voltage would track that, as it's just the plate supply minus the voltage drop across the plate resistor, which is in turn proportional to the plate current.
mental ruin
I'ma gonna need to read that a few more times to grok but thanks ๐
glacial spruce
Reading more about the PG-200 protocol, it's 5V so an Arduino could generate it directly, it might even be able to invert it if required (many UARTs can). And you can probably ignore the busy lead, so you only need to drive one wire.
mental ruin
@bright valve do you have a PG-200 or other device that speaks the protocol? Having something to compare to would make the job 100X easier
bright valve
I don't... I guess I could get one and then sell it. I see your point!
glacial spruce
Failing that, try having the Arduino just send the most basic message (start, address, data: 3 9-bit quantities) and see if the synth responds appropriately.
If the UART won't do it, there's a 9-bit software serial library https://github.com/addibble/SoftwareSerial9
And it can do the inversion too, if needed
bright valve
Nice! I'm going to try and set up with UART to start, and try those basic messages out. This is all great help and advice I really appreciate it. It's my first synth project so I'm excited to get frustrated at it ๐
bright valve
Thanks! Will do
mental ruin
an now I'm reminding myself that I have all the parts for my FM project sitting in a box next to me, judging me
glacial spruce
After far too long, I got my TDA7000 based FM radio working, but so far, the pendelaudion version doesn't.
dull basalt
Im considering building bluetooth headphones for myself because im starting to listen to music alot more, what are some design considerations?
It doesnt need to output top quality audio, i would just buy a commercial set if i wanted a really good pair.
this is more of a for fun project, but i would like it to be about the same, or better than a 20$ set of wired earbuds you might buy at the store
Im thinking of using one of these
has anyone used one of these before? what does the audio sound like?
azure carbon
Anyone here have an Ai Thinker ESP32 Audio Kit? It costs something like 11.3$ in China. Here is the board: http://www.ai-thinker.com/pro_view-69.html (page also has buy link but everything is in Chinese). Google translate seems to struggle with this page for some reason, and the wiki links are all dead.
It looks like it has grove pins, a couple of micro USB ports, a couple of microphones, two audio jacks (I guess input and output?), and a microsd card slot.
mental ruin
@dull basalt I was thinking about doing the same a while back and got as far as buying a module from microchip but never got around to making it do something after some preceding failures with a similar but different modules
All sound over BT will be lossy but the real factor will be everything between the module and your ears.
lol , it looks like Roving Networks == Microchip now; that would explain why it sounded familiar
Design considerations would be keeping your analog signal paths separate from the digital; you don't want to have your analog and digital components sharing the same ground except for a final joining point near the power supply; otherwise you'll get noise in the output signal because your analog bits' won't have a stable voltage reference with the digital bits making the pixies all wibbley wobbley
Also bypass caps are your friend
FWIW I'm no expert, just passing along what I've heard + a little hands on experience
oh right, I came in here to ask a question ๐
Could one intentionally cause distortion by constructing an amplifier such that the peaks of the amplified signal exceed the amp's ability to produce the "correct" waveform? For example if you had a 2V peak to peak signal coming into an amp setup for a gain of 6, but that only had +/-5V rails? presumably the peaks of the input would get as high as 1V, and with a gain of 6 they would hope to be amplified to 6V, however the amp would only go to 5, so anything above ๐ค 0.83V would end up clipped
it'd be like trying to measure an acceleration that goes to 11g with an accelerometer set to +/- 8g
glacial spruce
Yes, a clipping/clamping/limiting arrangement like this has been known to be used to condition inputs so some levels can be measured without higher levels causing confusion or damage.
mental ruin
interesting
tangential: Tubes are ridiculous and awesome
A beam tetrode's "beam confining electrode" (top left) is tied to the cathode and directs electron flow into a beam and onto the plate. The beam confining electrode is the tube's fifth electrode. The heater wires are shoved up inside the cathode, which is placed inside Grid NO.1 (control grid), which is placed inside Grid NO. 2 (screen), which is placed inside the beam confining electrode, which is placed inside the plate.
glacial spruce
Agree on both counts. The sort of "soft limiting" tubes do when they're overdriven produces similar harmonics that the human ear does when it's overloaded. I have a hypothesis that this may be part of the reason people have long claimed that tubes sound "louder" for the same wattage.
I'm still building stuff with tubes because I enjoy it.
There are even little breadboards made for the purpose.
mental ruin
awwe!
glacial spruce
And electronic learning sets
mental ruin
Dad and I started but never finished a 12ax7 based distortion pedal years ago which got me interested. As it turns out the circuit for that was one of the first non-trivial schematics that I mostly understood. 4 eons later@scenic axle convinced me to build a vali mini kit which is adorable and sounds great
now I just want to shove these little tubes in everything
glacial spruce
Oh, great fun! I learned on tubes because when I was a kid, they were getting discarded as everybody moved to solid state kit, which I couldn't afford. It was nice being able to understand the electron flow and look at the actual parts, which were big enough to see inside.
mental ruin
totally
glacial spruce
I built this monstrosity a few months back. Hybrid dual-band AM/FM radio. Tubes, transistors, an integrated circuit, and a JFET because why not.
mental ruin
๐ฎ
that ear piece brings back memories; pretty sure I had one of those from one of those "N in 1" electronics kits
what is that kit?
glacial spruce
That's a Lectron set (well, a few of them). http://www.lectron.de/
The blocks are magnetic, so they stick together, and the sides and bottoms are clear so you can see the components inside. My favorite electronic learning set, been made since the late 1960s, and they've added a bewildering number of types and modules over the years.
mental ruin
that's super cool
bistro math says the patent has expired so I assume there's folks making compatible stuff?
glacial spruce
I haven't seen any. The closest I've come across is Brick'R'Knowledge and some of the Gakken kits.
mental ruin
huh
I suppose it's possible they were able to keep their prices low enough that given the size of the market it wouldn't make sense to compete? Plus if they keep making cool stuff + brand loyalty, etc.
glacial spruce
They made some amazing experimental stuff (nixie displays, a little oscilloscope, this 4x4 bit core memory array, etc.) http://www.g-stabe.de/lec/ksm44-mg.PNG
mental ruin
neat!
tight stratus
I built this monstrosity a few months back. Hybrid dual-band AM/FM radio. Tubes, transistors, an integrated circuit, and a JFET because why not.
@glacial spruce Whoa, what kit is that?
glacial spruce
It's a Lectron set (scroll up a few for the link)
tough juniper
i was putting together a XFM2, which uses a cmod A7 as the synthesis engine and a UDA1334A to do stereo output. When doing the audio test it's absurdly noisy. i can hear the test frequencies faintly under the noise. Everything appears to be functional wrt to the circuit.. anyone have a starting point for debugging? is it possible the uda1334a is busted?
glacial spruce
I'm not familiar with that module, but I've had issues like that that turned out to be bit/byte order/synchronization issues, so the sound data was interpreted incorrectly, with the low level information loud, and the high level information quiet.
tough juniper
interesting
maybe the bitclock is wonky
i wonder if my solder bridge connecting the fpga to the bitclock is introducing a little too much resistance
glacial spruce
I doubt a solder bridge would be an issue, but those thin traces will have some inductance.
tough juniper
oh that was just a diagram the author provided, i did it on a perfboard with some jumper wires and solder bridge connections
rich gyro
anyone got a good link to a really cheap audio compressor?
trying to compress my audio out on my computer for movies(wow, they dont know how to mix audio these days...)
tough juniper
are you looking for hardware ? software? multiband?
rich gyro
hardware
im a musician, so, i know a little about these things.....just not trying to pay 150 bucks so that i dont have to keep hitting the volume knob every time something gets into a "Fight Scene" and then they discuss why they are fighting using only whisper volume level voices!!!!!!!
going between pre->post amp
(computer to reciever)
or even if i knew of a shemetic and some decent parts.....
pallid latch
If you want to go that ambitious, you can look at the example designs from http://www.thatcorp.com/THAT_IC_Products.shtml
rich gyro
the preamp is computer output, post amp is a reciever......just need something in between to cool it down
tough juniper
phonic pcl3200 is usually really cheap used
not very good
but should be able to do what you want
it's definitely going to mess up the sound a bit
tough juniper
i havnt, ive read people talking discussing their merit or lack of merit on gear forums
you could also make a rpi with dac/adc hat and use software
rich gyro
been quite a while since i've been on any gear forums!!!
rich gyro
(like 2k4/5)
tough juniper
lol
rich gyro
yes, but latency?
tough juniper
that's a good Q
rich gyro
i mean W7....SMH....
i plucked a string, it was like 500ms......and in recording terms...OUCH!
tough juniper
oh yea you need asio in windows or the latency is huge
rich gyro
if i want to watch A Bad Lip Reading, that would be awesomes!
yeah, the AC97 driver got bloated A F!!!
XP was decent with the AC97....
"And along came seven....."
molten hound
I was directed here from #general-tech - While trying to do the snake charmer tutorial on learn.adafruit.com I ended up with my CPX speaker no longer working. TO make sure it wasn't a script error, I loaded in other scripts that play sound that have worked on that board before and they no longer make noise. How can I fix this (if it's fixable) ? How can I debug it?
The only info I can give you that I observed was:
when I was running the program, instead of getting audio, I got a tick tick tick or a super tinny audio
The board got so hot on the bottom that it was painful to touch
As far as I know, I didn't short any wires
but looking at the alligator to wire cables now, the part that would connect into a breadboard has an exposed metal area so perhaps those touched? certainly the alligator clips didn't touch and I had them connected to the right areas
glacial spruce
Sounds like a chip got damaged ๐ฆ
molten hound
Bummer. I was hoping it wasn't that. But at least everything else seems to be ok.
glacial spruce
Typically things getting hot is an effect (and/or cause) of damaged semiconductors, unfortunately.
molten hound
Yeah, seems to follow me around. Back in undergrad I once got a ceramic resistor literally red hot
dusty rivet
Reminds me of when (a few months ago) I grabbed a film resistors and embedded the shape of a resistor into my figures. I didnโt realize the voltage from the power supply was spiking over 20V ๐
glacial spruce
I was testing out a gas tube I had bought from a surplus outfit, was not getting a good glow from it, so I turned up the voltage and fried the current limiting resistor. Oops.
molten hound
Reminds me of when (a few months ago) I grabbed a film resistors and embedded the shape of a resistor into my figures. I didnโt realize the voltage from the power supply was spiking over 20V ๐
@dusty rivet Yeah, I got burned really badly in undergrad. Once from that resistor and once from a transistor.
In other news, I can get audio if I connect the A0 pad to my headphones so if anything, I only blew out the speakers, I think?
It's been >15 years since undergrad so a lot of the electronics knowledge has atrophied
dusty rivet
Itโs done the same in most undergrad degrees
glacial spruce
Possibly the speaker amp instead of the speaker itself?
dusty rivet
Everyone wants to be a project manager now days lol
glacial spruce
Not me.
dusty rivet
Not me either. I got stiffed for an FPGA role for not being EE. Iโm CompE and do more with FPGA than EEs do ๐.
Probably my only gripe with computer engineering is most people think we are CS
molten hound
that stuff is so silly
one of the python podcasts I listen to
they were talking about the meddling that HR does
dusty rivet
Nothing wrong with CS, but most of my coursework is electrical based lol
molten hound
like one of the guys wrote an ad where he didn't care about the degree if you had the right experience
and HR added a degree anyway
and in another case they were asking for X years of experience in some language when the language had been around for <X years
glacial spruce
One of the replies to that thread was great, it was from the author of the language.
dusty rivet
Yeah, Iโve see that a lot
Recently too
I also dislike when people have been in a field for X years and only have their minds set on particular degrees for direct hires and then shoot themselves in the foot when they canโt find enough people to fill roles
molten hound
Since I sometimes find myself as the hiring manager, the only time degrees are important for me are fresh grads unless they have some good internships or list something on github that shows they have profficiency. Once I get to someone who's got a history, I look for what they did vs their degree. I think that's because for both my wife and I, we didn't end up doing our degree stuff
I'm an EE and for the past 15 years have done software or management
my wife is a Chemistry Major and she mostly has done biological research
Until I got sucked into the Arduino world a year or so ago, I hadn't touched anything EE in all that time
dusty rivet
Iโll be a fresh grad this December, I do a lot of projects though
Though I am also older than most fresh grads by 6+ years
I think it has advantages though. I have a lot more drive than my peers to do projects and activities to apply the knowledge I have learned.
molten hound
@dusty rivet I'd definitely highlight those projects on your resume (unless your jobs between HS and graduation reflect that). If you can get past HR, any good manager is going to either check out your github or have their top engineer/programmer check those out to see if you're legit
dusty rivet
I list them on my resume and itโs helped a lot, Iโm being considered for a lot of embedded roles which is nice
It will probably be my only IN for FPGA roles being a โrecent gradโ hire
I also post regularly on LinkedIn about projects since itโs a good professional environment to share outside of Twitter and github
This got off topic real quick ๐
Just realized haha
rancid hollow
Not exactly audio but related... getting into Teensy boards cause Iโve heard theyโre great for MIDI projects. Which Teensy should I get if I want to send midi signals from my computer into the teensy to trigger Neopixel patterns?
versed torrent
If you get something like a Circuit Playground Express - or a Feather M0/M4 Express - then you can do MIDI right over USB from your computer. And you can do it in Python if you want.
the CPE board has 10 Neopixels right on it - I've used to be a visual metronome.
rancid hollow
Can you do the same thing with a feather huzzah esp32, or does it have to be M0/M4 express? And why, if you donโt mind explaining?
glacial spruce
One advantage to the ItsyBitsy is it has a built-in level shifter for driving NeoPixels, however the Teensy boards have an add-on board for that too.
versed torrent
Circuit Python has MIDI libs, which makes it all pretty easy - but you need a board that runs it Circuit Python. The Adafruit page for Huzzah ESP32 doesn't list Circuit Python - so for that board you'll need to code in std. Arduino C++.
But, if you do get a C.Py board - see https://learn.adafruit.com/grand-central-usb-midi-controller-in-circuitpython/code-usb-midi-in-circuitpython
rancid hollow
I donโt need it to send midi data into a computer, I need it to receive midi data from a computer. I understand that a lot of codes allow for 2 way communication but Iโm a little tired of wading through tons of project regarding how to make a midi controller, when Iโm looking for something that receives midi to trigger neopixels
That being said Iโll start A/B-ing resources on teensy boards w teensyduino vs Adafruit boards w circuit python
dusty rivet
I donโt think you necessarily need a MCU to do what youโre wanting, I do believe itโs been done other ways before that might be less involved.. Iโll get back to you on that though
Iโm thinking of something else, nvm the above
obsidian cove
@rancid hollow midi is just serial/uart at a specific speed, it's not rocket surgery. in arduino land it's about 5 lines of code to open the UART and receive the midi data.. you can copy paste those 5 lines from just about anywhere.
versed torrent
Well, MIDI over USB is a bit more involved.
But there are libraries - like this one: https://github.com/BlokasLabs/usbmidi
Circuit Python also has libs for both MIDI over USB and MIDI over BLE
pearl vigil
For receiving MIDI over USB you'll need to implement a USB host. I remember the [in?]famous V-USB library has such support
IIRC there's even a specific example code for MIDI host over USB
V-USB is for AVR though
versed torrent
No - actually, MIDI can be sent in both directions between host and device.
A common pattern is that the MCU based unit is a device to the computer host. But the connection is a pair of MIDI connections, one in each direction.
ember kayak
is DFRobot a good manufacturer? I've been looking at their audio amplifiers lately since i'm working on a basic bone conduction setup, and they seem too good to be true; ROHS3, stereo, 5-ish dollars, etc
bold wigeon
Hi, im using a MCP23S17-E/SS I/O expander connected to an arduino to send and receive gates from eurorack synths, do i need a buffer between the i/o expander and synth i send/recive from?
glacial spruce
I'm guessing you do not, unless your gate signals are a different voltage range, or have a different ground reference.
Or they're low impedance inputs (which I doubt)
bold wigeon
i made sure that the io expander is operating at 5volts as that's the level of the (most) gates, hmmm yeah, this i a problem, gates dont really follow any standard. i guess they could be 10volts in some odd cases
so i guess i attest need some overvoltage protection
at lest^
glacial spruce
Probably a good idea, there's still some old vacuum tube synth gear in use
versed torrent
I did my trigger gate send/receive interface to a 3.3V developer board with just diodes, resistors and transistors.... but I did want the output to be 0 ~ +10V.
bold wigeon
Thx!
So this is my (messy) schematic, the "ddx" nets are going to the i/o jacks, maybe this is a convoluted way of doing this, but i want the be able to change if the jack is a input or output in software. and this is what i came up with ๐ now i just need to make sure that noting will happen if some odd module put out a 10v gate or even 12v
glacial spruce
I'm guessing a simple current limiting/clamping network would be sufficient
bold wigeon
Ok, new to this so if you could point me towards some examples of that? im thinking about just putting a zener diode in series with a resistor to each input and ground, would this be ok?
glacial spruce
Yes, the resistor is the current limiter, and the zener is the clamp: that's a usual approach.
bold wigeon
is this ok? what values are a good idea? are both resistor a good idea? haha, no idea what im doing
glacial spruce
You do not want the resistor between the zener and ground, it will defeat the purpose of the zener. The value of the resistor depends on the impedance of your gate signal.
For many systems, 1k to 10k will work, but if the gate inputs are TTL or otherwise providing operating current to a circuit, you may need a lower value (which will also give less protection).
bold wigeon
Thx, so i made it like this now, i read somewhere on a forum that the standard impedance of eurorack i/o was 1k so i used that as a resistor value
glacial spruce
That would form a 2:1 voltage divider, which may be fine
versed torrent
I think I missed something: are these inputs or output?
glacial spruce
Generally not, that would cause an asymmetrical voltage shift
They're both: which is part of the issue
glacial spruce
We have that
slate coral
guys i found this tiny thing in my old Headphone is that i mic?
versed torrent
On the chip itself?
slate coral
it's really tiny!!
glacial spruce
Looks like a mic to me
slate coral
woow
glacial spruce
Right next to the WiFi antenna which seems like an odd choice
slate coral
yea it's a Bluetooth Headphone
can i use this mic in another thing?
or it's just for this Headphone
dusty rivet
@glacial spruce if the zener is placed before the resistor and still tied to ground, how does that shape the voltage characteristics? Any different than it being after it in the above configuration?
glacial spruce
You want the zener on the side of the resistor toward the circuitry you're protecting. Then if a voltage comes in that's too high, the zener will clamp it to ground (if it's negative) or the zener voltage (if it's positive), and the resistor will limit the current to a safe level.
dusty rivet
Makes sense
versed torrent
When doing this, if the MCU is configured to be an output .. and the user mistakenly plugs the jack into a +10V output of the synth... What protects the MCU?
glacial spruce
That's what the resistor and diode are for.
bold wigeon
getting a bit confused, or more confused would be more accurate
am i doing it right in the last picture? checked some examples online and i think its basically the same as in my last image
glacial spruce
Looks right to me.
versed torrent
What's the current "best practice" for MIDI libraries? I have a project - I want to support both USB MIDI on some boards, and serial based MIDI on others.
azure carbon
What's the current "best practice" for MIDI libraries? I have a project - I want to support both USB MIDI on some boards, and serial based MIDI on others.
@versed torrent
It's the current "Gold Standard" for MIDI libraries IMO
Does everything from serial MIDI to USB MIDI to rtpMIDI (Apple's WiFi MIDI) and Bluetooth MIDI
I'm waiting to receive my ESP32 so I can test the wireless features out. But until then, I can vouch for its USB and Serial MIDI capabilities ๐
You simply change one line of declaration to choose the backend. Everything else remains the same.
versed torrent
Yeah - that is - wow - that is EVERYTHING. But it is also way more than I was after. And much more of an application framework.
It looks great - and if I were building my own controller - then that looks nice.
azure carbon
It looks great - and if I were building my own controller - then that looks nice.
@versed torrent
It takes you 20 minutes to turn a cheap Arduino Joystick Shield and a Leonardo into a USB MIDI controller. Literally one line per control.
When I first built a midi controller with this library, I was too ashamed to push anything to GitHub. Still am. Made a few different controllers but I could literally write them from the scratch each time and it's still only take minutes. It's about as easy as boiling pasta.
I just wish all these older shields would work with my 3.3v due lol
They should've skipped the 5V pin on the due for the 3.3v, or swapped the positions of the two so old shields work with new voltage
versed torrent
yeah - it looks great - if that's what I was doing.... I'm building a MIDI looper - like a tape loop for MIDI... and this is somewhat overkill for that - and I think too much overhead for the tight timing things I need to do.
azure carbon
Aah. So MIDI is the control input for this looper?
versed torrent
no - MIDI is what is being looped!
azure carbon
Is the looper also in an MCU or are you running guitarix on a raspberry Pi?
Aaah
I see
versed torrent
(the controls could be MIDI, or touch switches, or foot switches) -
azure carbon
Then you want the forty-seven effects midi library
versed torrent
I'm planning on using a SAMD51 - a Feather M4 Express
azure carbon
And handle your own transport
But honestly I think there's passthrough methods on Control Surface to accomplish anything
versed torrent
Yea - the problem with that library is that the interface to the transports is in terms of bytes, not messages.... So going from USB to USBTransport, messages are decoded into bytes, then into the upper library and re-parsed back into messages... kinda yikes
I don't know why the interface between that library and the transport layer wasn't in terms of MIDI messages - but is in bytes -
azure carbon
Aah darn
If you're writing a fresh object oriented midi library, I can contribute ๐
versed torrent
anyhow - my current plan is to use the Adafruit TinyUSB MIDI support, but use the message based interface, not the Serial based one.
At some point - perhaps - this is one of two projects I've got going on that are going to be doing MIDI with very careful timing - so I may just indeed build up my own (open source, natch)
azure carbon
Keep this channel updated about how it goes. Haven't yet touched TinyUSB.
versed torrent
The other project is much further along: Pulsar Buddy ( https://github.com/mzero/pulsar-buddy/wiki )
azure carbon
I wish TinyUSB had support for Blue Pill's Arduino Core.
versed torrent
(the little embeds of links to github are always useless, as it grabs my profile icon, not the image of the project!)
azure carbon
Projects have images? Guess I haven't been paying attention.
whole pasture
I'm a little confused on how to use this mic with an arduino:
it says the max vpp is 2V, and the DC offset is 1.25V-- does that mean that the output ranges from
0.25v -> 2.25v?
solemn flint
Yep, exactly, so you should be able to feed it into an analog input on an Arduino.
whole pasture
Awesome, thanks for the confirmation!
still lance
Hello group.. anyone know of a pre made pre configured Led strip set that pull Its audio Input not from a built In mic but has like an audio In jack?
vocal knot
so, i'm trying to work on a VCO type project (something like what would eventually go into a modular eurorack synthesizer, although that's a long way away)
and i feel like i must be missing something
because most audio circuits seem to want a split power supply (e.g. the eurorack standard is ยฑ 12V) for op amps etc
but i just can't seem to find that kind of thing readily available for sale anywhere like the ubiquitous aliexpress buck/boost regulators
i see this on adafruit https://www.adafruit.com/product/2591
so clearly it exists, but there's nothing that i can find that's adjustable and can do any significant wattage
like, does everyone attempting to make an audio circuit that needs a clean power supply just roll their own?
from what i've read a clean power supply is really important for that kind of thing, and the easiest technique is to use a buck/boost regulator to get +- 13-15 V and then linear regulators to get that down to 12 cleanly
can anybody tell me if that makes sense? and if so whether rolling my own is a really bad idea or if it's reasonable-ish
obviously i'm not asking for someone to design this for me or whatever, but just seeing if this is the right approach
or for that matter, is this not worth the trouble and i should just stick some batteries together into a power pack with a center tap of some kind
lol
versed torrent
when building for Eurorack, you generally assume that the euro rack system your board plugs into will supply +12V & -12V.
there is a std for the power ribbon connector. so get yourself a euro rack power supply, and use that
glacial spruce
One possibility is chips like TPS7A39
vocal knot
right right, definitely would not be worrying about this for prototyping modules
but in general i would like to have something smaller-scale that i can assemble into sort of a semi-modular setup of my own
tacit jay
Not so much help, as, have people here built Eurorack modules?
I'm curious about how hard it might be.
I think I've accidentally triggered someone else having an obsession.
glacial spruce
I think at least one person has.
tacit jay
@glacial spruce I mean, odds are good, right?
There's approximately n thousand people on here, where 2 <= n <= 9, right?
glacial spruce
More specifically, I think I saw some traffic in #help-with-hw-design recently on that very subject
tacit jay
oh, cool!
I know very little about most of the things people are interested in here.
But so many of them are so shiny!
versed torrent
are you asking about designing D.I.Y. eurorack modules? or building from kits? But yes - both here and in #help-with-hw-design there are plenty of modular synth folks.
I've designed and build some things - but not Eurorack specifical, just general purpose analog modular synth.
dull basalt
@vocal knot The EML 101 has a good set of schematics available online.
That one used two secondary windings of a 120VAC (input) transformer.
Also PAiA still has some PSU listings:
https://www.paia.com/products.asp?cat=19
There may be detailed documentation available for one or more of those.
PSU == power supply unit
This will give you a complete manual for a power supply kit from PAiA including a good schematic and theory of operation:
It is an LM317 and LM337 based design.
There are probably good bench PSU designs on the market as well, already assembled and ready to use.
(and they probably cost a small fortune to obtain)
dull basalt
That 9770R-15 PSU is simple enough to breadboard, to get a feel for it on the cheap.
If you want the full 650 mA (per leg) delivery capacity, breadboard would be sub-standard. Could dead-bug it, though.
vocal knot
thank you, neat! I'll check all of those out
analog jasper
Hi audio people. I am doing something similar to https://learn.adafruit.com/pumpkin-with-circuit-playground-bluefruit and have noticed in both my configuration and the video there is a slight pop when the sound starts and stops. This is more pronounced with my setup. Is this from the 2.5W classd mono amp turning on and off? I am using circuit python and .wav files
wave_file = open('sounds/' + name + '.wav', 'rb') # using wave files from sounds folder
wave = WaveFile(wave_file)
audio.play(wave, loop=loop)
glacial spruce
Could be that or an abrupt change at the beginning and end of the sound file, I suppose. Or some other thing.
analog jasper
So add some quiet space to the front and end of the wav?
alpine cloud
or see if it pops with a silent file
glacial spruce
More like a fade-in than a quiet space. I suppose it depends on what the idle state of the signal is, ideally your sample would start and end at whatever level that is.
analog jasper
Thank you that gives me a direction to start investigating.
analog jasper
Just to keep a record... adding silence to the front of the wav results in pop-silence-soundfx..
tiny ore
Howdy, I'm trying to connect the following components together.. Arduino Uno, Adafruit FX mini sound board, PAM8304 amp, and Speaker(s) How should I be powering this, and will it even work?
versed torrent
Sure - that should all work... but quick question - which version of the FX board do you have? There are six!
@tiny ore - are you planning on connecting serial from the Uno to the FX and controlling it that way? That should "just work" - and Adafruit even has a library for it.
tiny ore
@versed torrent its the mini, that does not have the built in amp, and no jack. It already has sounds loaded to it, and is being controlled by serial from the Uno. The issue I have right now is that after I connect the outputs of the fx board to the amp, the speakers just make a popping noise.
versed torrent
hrm.... that's not good....
how are you powering the FX and the amp? And, how have you connected it to the amp chip?
also - quick check: If you wire just plain small headphones/earbuds to the R/L/Gnd lines on the FX --- do you hear the output you expect?
tiny ore
I think that's where I am going wrong. The Arduino is being powered by USB and then everything else is connected to that via breadboard.
versed torrent
using which power from the Uno? and I'm assuming everything is correctly sharing GND
Got a picture or diagram of what you did?
I'd link +5V out from the UNO to Vin on the FX
versed torrent
which ever will convey what you did - we could start with a snap if that is easier
versed torrent
Is that white jumper connected to RST on the FX
And the red/black power/gnd wires off the breadboard at the bottom - that's just for testing, right?
But in general - looks right - I'd say if you have a spare headphone jack - wire that in place of the amp - L/R/gnd to the FX directly - and see if you can hear the right audio first - at least that will tell us if the error is in the FX side or the AMP side
Does it look like the UNO is communicating with teh FX?
tiny ore
Right
Oh It is, I had a different amp connected and it was working
The PAM3402
I switched to this one because it was stereo
versed torrent
do you have an Oscilliscope? The FX board's outputs are labeled "AC" - but from the looks of the schematic - I think they are all +V only.
versed torrent
So - I'd say it should work..... do you have any spare caps?
who's breakout board for the amp is that?
The amp chip requires a few caps - and that board has a few - but it would be good to check which it hads, and which it still expects
tiny ore
@versed torrent Breakout board? Which one? In that picture is an Arduino Uno (copycat), an Adafruit FX Soundboard mini (lower breadboard) and a PAM8403 amplifier (top bread board)
versed torrent
good morning! I meant the PAM board - I have the chip datasheet up - but would like to have that board's
tiny ore
I can show you the link where I purchased it, it's one of those chinese chip deals.
I have like 5 of them.
versed torrent
One issue might be power - you could put a 10uF electrolytic cap across power and ground on the PAM breadboard (be sure to get polarity right) - that will at least mean power is stable there.)
tiny ore
versed torrent
Okay - visually decoding the circuit from those images (!) I see that that board has the required caps, resistors, and a decoupling cap on it
So - that's nice - and we can ignore that aspect....
tiny ore
nice
versed torrent
I'd still throw the 10uF on the breadboard - you're running 5V over a long run - with two high speed digital devices in the chain -
but - unlikely to be the source of "click, no sound"
Can you verify the amp board works alone? Or perhaps generate a 1kHz sine on the Uno from its analog output and run that through the amp?
Seems unlikely to make a difference - we know the uno + FX board pair works, as it worked for you with a different amp, right? --- so something is unhappy with that amp board and how it is connected.... but seems like it is pretty straightforward!
Maaaaybe try using the 3.3V source from the UNO, rather than the 5V?
Both FX and amp boards are spec'd to accept 3.3V power
tiny ore
I have it hooked up right now with a PAM8302 amp and it works.
although, it does sound a bit iffy. I'll hook it up in a bit and try to snap a video.. that might help. I do appreciate you trying to help me!
azure carbon
Does the SAMD21 do USB audio out? What's a good library for that?
glacial spruce
As in emulate a USB audio device?
echo hedge
Not yet. I'm not sure Full speed has enough bandwidth to carry audio
solemn flint
It should. CD-quality audio is only 1.4 Mbps.
mystic wren
usb 2.0 has enough bandwidth for multiple streams of audio
echo hedge
๐ so 12mbps could do it
usb 2.0 includes high speed 480 mbps which we don't really leverage in circuitpython
tinyusb is the place to start adding support
bonus points for adding video ๐
azure carbon
So there's nothing like the Teensy Audio Library for non-Teensy boards then, is there?
glacial spruce
There are, like this AdaFruit fork of it: https://github.com/adafruit/Audio
azure carbon
Seems to be SAMD51-only. https://github.com/adafruit/Audio/blob/master/library.properties
glacial spruce
Oh, did you mean a particular specific non-Teensy board?
azure carbon
Should've specified I'm looking for something for the SAMD21 lol
glacial spruce
It seems like it ought to be possible, I think the SAMD21 has enough horsepower, but I don't know of one offhand.
raven snow
I am attempting to use delta modulation https://en.wikipedia.org/wiki/Delta_modulation to produce voice audio in a peizo. any suggestions on hardware peripherals i could hook up to? ideally i dont want to bitbang. my initial thought is SPI but i don't have a dedicated bus available. I don't think i2c would be a good fit :/
glacial spruce
Maybe a PCA9745B?
raven snow
that could work. or using the on chip PWM controller and an interrupt at 32KHz-44KHz or so
it probably would need to interrupt much higher than that, probably more along the line of 100s of KHz
versed torrent
@raven snow - You can use the standard Wiring analogWrite() function to set the PWM value on any of the pins that implement PWM... However the core implementation uses far too low of a carrier frequency to do voice. For voice, you'll need minimally 8kHz bandwidth - so the carrier needs to be up about 100kHz or more.
If you are using a SAMD21 based board - I have code that pokes the registers to get the carrier up - and then you can continue to use analogWrite(). Happy to share if you want it.
The same thing should be possible on a SAM51 - or even other boards if they support carriers that fast.
light crag
My dad's amplifier broke yesterday it works but low sound now you need to have volume on max to hear i haven't touch anything yet so yeah
Whats the reason for low volume on amplifier
It's pretty old tho
Capacitor?
glacial spruce
Probably a poor connection, maybe in the volume control or input switches.
light crag
Probably a poor connection, maybe in the volume control or input switches.
@glacial spruce and how would that be a problem when it worked fine yesterday
glacial spruce
There are lots of possible reasons.
light crag
i would like to fix it so we dont need to buy a new one
glacial spruce
The procedure for many such fixes is similar: divide and conquer. Figure out where in the circuit the signal is getting lost, and narrow down from there.
light crag
I'm thinking it's something with pre amp(if it has any) or bad capacitors idk
Power amp is ok otherwise is would be dead
glacial spruce
Do the usual things, operate the various switches, try a different input, etc.
light crag
I tried all inputs radio aux and turn table
There also tape monitor but I don't have cassette
All of them is the same thing
I hope it's not a ic that's just a pain
Well how do I know if a capacitor is bad if it's not bulge
glacial spruce
You can use a capacitor tester, or try bridging/substituting with known-good capacitors.
Why are you guessing it is a capacitor? That seems unlikely to me in this situation.
light crag
Idk really that's a guess
west fable
my soundboard's act light is lit
and it's very bright
and i don't know what to do about that
wait i think it's playing music and it's just not connected to a speaker
is that it?
glacial spruce
Might be, I can't tell from here. For too-bright LEDs, often a bit of tape or nail polish will curb their brightness (you can also open up the device and install a different current limiting resistor to lower brightness, but that's not for everybody)
west fable
oh no i was saying that the act light is lit and i haven't done anytthing to it
i just plugged it in so i can download sounds
and it's registered as a sound device
and i can't upload anything
also no it's not playing music i connected it to the speaker and it didn't play anything
although the speaker seems to be warming up when it's connected
i have no idea why this is happening
@glacial spruce is this just a hardware issue that i can't fix, or is it something that i can do to fix
glacial spruce
I don't know enough about your setup to say.
west fable
right i will take a picture
that's all i did
all i did was connect that to the computer
there isn't really much of a setup
glacial spruce
Hmm, that should show up as a mass storage device (like a USB thumb drive), not a sound device. Also, I don't see any speakers hooked to it.
west fable
oh yeah i unplugged it by mistake
but yeah, i have no idea why it's showing up as a sound device
it gives me the option to uninstall the driver
should i do that?
glacial spruce
I don't know, sorry.
west fable
dang it
okay upon checking in the device manager it's def the driver
because the driver says "usb audio device"
versed torrent
Woot! Anyone had problems sending MIDI SysEx over USB from a devboard? I found da bug!
It's in tinyusb, PR sent.
agile mirage
Hey does anyone know if 20W amplifier supports automatic switching from speakers to headphones when headphones are plugged in?
versed torrent
I don't think that would drive headphones well - at best you'd need to turn the volume way way way down
more importantly:
Since it is a class D amplifier, the signal out of these speaker blocks is a high frequency (~300KHz) PWM square wave. The inductance of the speaker smooths out this signal into audio frequencies of 20-20KHz.
I don't know if the inductance of headphones is right for this job.... maybe?
fervent yacht
how do i figure out what a notes period is?
i get the frequency part that's easy. Finding out what the period is however fells impossible, i have found nothing even mentioning that notes even have periods much less a list of which periods for which notes.