A mild overdrive. Kind of a basic dual op-amp soft clipper, but I tried to go hard on the "thinking" side of this by preparing a schematic and vero layout.
https://dunningkrugerfx.com/zenish
#Zen(ish)
tulip knot
thorny monolith
Oh I love the look of that!
tulip knot
thanks!
covert hearth
this is probably the prettiest minimalist pedal i have seen in my life, wow
tulip knot
thanks! it was mostly accidental, but I appreciate it.
kindred karma
are those wooden knobs?
tulip knot
yeah
kindred karma
you made them? i made some D shaft ones for my microbrute since the original became gross, using kneaded epoxy to make the D shape
tulip knot
yeah. i had some crap knobs that I'm never going to use and took the brass inserts out of them, then made the wooden part
kindred karma
they look great. how eccentric are they?
tulip knot
they're not too bad. They started out bad, but I initially made them oversized and then trimmed them to size on a drill press (like a half assed lathe)
kindred karma
oh nice idea
tulip knot
It's probably not great for the drill press (they're not made for side loads) but I took it easy and only used light tools like files and sandpaper.
they're still not perfect, but that process took out most of the eccentricity.
kindred karma
ah yes, dylan158 my lesser sibling
ah i missed reading one of these. i guess you're liking the C tone pot? B for gain isn't as good as A (you can even use a 1M)
the fill came out great, you can't see anything from the picture. it's a tecnique i'm keeping in mind if i need to, but i'd use metal filler epoxy
thorny monolith
I've filled holes with wood filler before
tulip knot
Did I get the number wrong? sorry
updated
I think C would be best for the tone, but I didn't have one, so I did backwards A for now. I'll replace it eventually if I wind up actually using this pedal.
I don't understand why A is better for gain, but in practice, I can see that it would be.
to fill the holes, I just covered them with tape from the inside and the put epoxy on from the outside. I left it a little proud so that I could sand it flush and not worry about having a divot to fill later. It was kind of annoying since I had them on two sides and had to do it in two steps (thanks, gravity) but it was fine. I thought about using JB Weld or something, but it's not actually conductive. I would have had to fill it with graphite or something.
foggy island
very cool, this makes me wanna do some more overdrives. i had saved some zen drive schems and now ima bookmark yers as well@
kindred karma
to fill the holes, I just covered them with tape from the inside and the put epo...
i wouldn't worry too much about the cheese effect. something to do with wavelength says that if the holes are small you still have an effective shield for longer wavelengths.
A is good for gain for the same reason the tone is good rev log: you don't want a linear variation in gain, but an exponential one that follows the dB curve
kindred karma
@tulip knot where's my maths?
tulip knot
what?
kindred karma
you said you'd calculate things about your pedal
tulip knot
did I? I have no recollection of this. I did calculate the cutoff frequency of the input cap, and we talked about that.
You said that the output cap was too small, so I upped it to an arbitrarily large value
kindred karma
i suggested other stuff, not really because I care, more for you
the output cap is good
relevant discussion #👟│pedals message
tulip knot
i honestly don't know how to do most of that, and in some cases didn't know what you meant (like when you talk about calculating the gain, was that regarding the 1k resistor that was across two lugs of the gain pot, or related to the input cap? If the latter, I don't know how that would effect it.
I know how to calculate op-amp gain when it's really simple, but that whole thing where some of the feedback loop is trickling out to VREF makes me not know how to do it.
kindred karma
take just the two resistors, and see how much the gain changes with 0 or 1k ohm feedback. take the lowpass filter and calculate the extremes for the cutoff frequency
tulip knot
so that the fact that the feedback leaks to VREF instead of actual ground is irrelevant to gain?
I don't really get the whole VREF thing. I mean, I get that there's a voltage divider in the power supply but except for cases where you need to power an IC with less than 9V, I don't really understand why it's used.
(unrelated, I think I found a typo in the power supply of one of your PUP schematics)
kindred karma
actually your feedback doesn't need to go to vref since there's a cap in series, just any low impedance dc point. it doesn't hurt though
vref is your "reference ground" which sits in the middle of the supply so that you can go both above and below it. it's in theory just like a dc supply, and as long as you don't dunk or pull excessive currents, even two resistors and a cap are enough to give you something reliable just to bias the circuit at that voltage, just as a reference point
so all in all, you can treat it as ac ground unless you did something wrong. the capacitors will have an in impedance, but you know there's a frequency at which they are irrelevant so you can start from there (but also check later)
tulip knot
ok, i can do the math tonight then. i think i intrinsically get that 1k isn't going to make an appreciable difference, but will work it out. for the lowpass, you mean the main tone control? I did do that when I was messing with the cap size, but didn't take extensive notes. I know that I made it 3.3n when breadboarding it, but changed it back to the stock 4.7n after hearing it through a real amp
kindred karma
yeah it might be worth doing that so you know what those cutoffs sound like roughly
tulip knot
I realize that there isn't literally zero resistance in the feedback section when the pot is turned all the way down (and when the 1k resistor between the pins is removed), and there's little danger of ending the universe by dividing by zero, but when I put a small value in like 1 ohm, the gain basically goes to 1.
tulip knot
I used a calculator, but took notes by hand. Even though I hate dealing with .0000000047F
kindred karma
yeah those are right, i double checked them
please use powers of 10
at least they cancel out easily
tulip knot
What do you mean? Like 10^-9?
kindred karma
anyway with the 50k pot 4.7n is the way to go, 800hz is a bit high for the maximum setting. otherwise i'd have gone with 100k pot and 3.3n
kindred karma
What do you mean? Like 10^-9?
yeah, that's less cumbersome
tulip knot
Those are just my notes because I needed to punch them into the calculator like that to do the math
kindred karma
sure, but you can save some trouble by clearing up the exponents beforehand, or use the calculator function for them (i never do tbh)
tulip knot
I don't know how to do that. I just type 1 / 2 / 3.14 / r / c
But don't worry about the arithmetic part. Thanks for checking the values.
kindred karma
so to wrap this up, the lowpass pot at half on a linear pot is tuned at 967 Hz, which isn't as bad as I thought, since it's not much less than one octave above the minimum, 1.7 octaves below the maximum probably because of the limited range
tulip knot
I definitely have it above the midpoint (i.e., letting more highs through) most of the time. And it varies with the position of the voice control.
kindred karma
if you have it on the trebly side then keep it rev log. the effect of the voice is that it apparently affects it by cutting bass
foggy island
I finally built a new breadboard/prototype pedal platform and made a zen drive for my first circuit! Started with yer schematic (and the original) and I’m really enjoying what I hear!
I got 4148+BAT41 and 4148 for clipping right now but my plan today is to switch up the clipping diodes a bit!
I also changed my Resistor for op amp bias to 1M and stuck with the A500k for gain
kindred karma
well, the turtle is just a little ways off now. as bass control i like the arrangement in the Timmy more
1M is always good, the gain pot value by itself doesn't mean much, just in relation to the other values
foggy island
True- especially since I kept a 47k resistor in there (a La tube screamer) Vs the 1k in most Zen schems.
“There” being the feedback loop lol
kindred karma
that just limits the minimum gain if i get it correctly
foggy island
Yup
kindred karma
i just skip it entirely, you can choose if you care about minium gain or saving a resistor
foggy island
I mess around with the tone on mine heh.. used some silly values (3K instead of 10K, 5.6nf instead of 4.7 or 3.3) so my filter goes from 9.5khz to 536hz
kindred karma
the range is about the same so i don't think those changes matter much, especially in the middle of the pot
foggy island
I like having the brightness option, especially when you have the “voice” control
Yeah not too crazy, I just have a baggie of 5.6nf that I’m using up heh. And there was a 3k lying on the bench
kindred karma
indeed, in the turtle i limited the lowpass to 15.9k with the stopper using values that wouldn't load down the op amp at that point
kindred karma
Yeah not too crazy, I just have a baggie of 5.6nf that I’m using up heh. And the...
that's how one uses those weird values 😁
foggy island
Any recommendations for clipping diode mixtures?
kindred karma
N.1 is definitely to not bother and change everything else instead, n.2 is #1078271870694080533 though. I recommend reading it because there are some relevant points on this kind of circuit
Not trying to make a thread fight here 😂
foggy island
Hahaha
I just read it the other day but now that I’ve built a circuit with that topology ima go back and reread!
Sorry for hijacking yer thread @tulip knot haha
tulip knot
No worries. Glad you got something out of it.
foggy island
Here is what I sketched out after putting together the breadboard last night. Obviously some changes will prolly be made but I’m digging it enough to put it in a box. I need a new OD to play with at band practice
tulip knot
Curious to see what you wind up with for the clipping and tone. Personally, I think I should have spent more time on my tone control and given it a little more range, yet am skeptical that putting MOSFETs in the clipping would be amazingly better.
foggy island
Yeah I was thinking it might make sense to roughly add up the Fv that the mosfets+ bats provide but ultimately the asymmetry is what I like. When I did symmetrical (4841s) it wasn’t as pleasing to my ears
tulip knot
Yeah, same for me.
I had that one weird Ge in there on mine, which I'm sure isn't essential, but made it somewhat asymmetrical. And that was my version of using up my weird bag of 5.6nF caps.
kindred karma
Sorry for hijacking yer thread <@675041223106625536> haha
i think chip would agree, that inspiring you to make something new is the best that can come from this
foggy island
That’s why I check this discord everyday haha!
kindred karma
Curious to see what you wind up with for the clipping and tone. Personally, I th...
changing the range is easy, change the cap and the stopper. the zendrive uses the moss in active mode I've noticed recently, so again to the true mos for more about that. I don't think it matters either but it's fun
kindred karma
Yeah I was thinking it might make sense to roughly add up the Fv that the mosfet...
might be me, but asymmetrical either sounds muddier or like there's a layer of clean separated from the distortion
foggy island
Hm well my first OD was an SD-1 so maybe in predisposed to enjoying the asymmetry 😆
I made a blue breaker style clone that symmetrical and although I enjoy the plethora of options I put into it (like wampler pantheon and KOT sorta switches), I still find myself keeping the SD-1 on the board over it.
tulip knot
Symmetrical and asym clipping are definitely different in an audible, non-magical way, so it's not surprising to me that people would have a preference. I have some of both. I did more breadboarding than usual on my Zen, and at least for this circuit, wound up liking the asym more, but it's probably just a matter of taste.
foggy island
Yeah, I threw some different diode configurations in and I’ve been enjoying:
[ BAT41 — 1n34 (a lonely ge diode from stompboxparts lol) — 4148 ]
[ 4148 — BAT41 ]
foggy island
So I made my stripboard layout and while I was working on the clipping section I was like… “well I could add a switch to take the 1n34 out.. add a symmetrical clipping option to please @kindred karma” 😂😂
But also I’m using a 125B enclosure so I got room for a switch in the middle of all my knobs
Oh also I think I’m switch back up to A1M for gain like @tulip knot had lol.
I drilled it already but didn’t get a photo cuz I have to go play a show with my band!
tulip knot
Yeah, I had a 500k in the gain at first, but there's no downside to the 1M. You can always turn it down.
foggy island
I think I’m gonna made my own thread tomorrow morning! I’m gonna paint the enclosure and start making the board!
kindred karma
Nice drill layout
tulip knot
Are you starting from my strip board layout?
foggy island
Nah I made my own, I like the challenge of making it + I gotta accommodate my building style. I prolly shouldve looked at yers as a starting place tho lol
I have saved variants in diylc for the various sizes of electro and film/ceramic caps I have on hand so I can make sure it’s all gonna fit if I’m using a chonky 50v 100uf for instance.