Recent content by JTEX

There's a tool specifically for that sort of nut, or you can probably fashion one out of some metal tubing: https://no.rs-online.com/web/p/potentiometer-knobs/0225760

There's a nut under the top. Tighten it and it clamps on to the (solid round!) shaft.

I hate wiring passionately enough that if I were to make pedals in some kind of volume, I'd try my best to have every component on the PCB. Jacks, switches, you name it. Everything except maybe the footswitch, due to mechanical stress/vibrations. It takes a lot of design work to make this happen...

I'm not a real engineer either. Best to try this on a bench or in a simulator, check for stability and so on.

R2 can go as low as U1 can comfortably drive without distorting, so probably not much less than 1k if you're using a TL07x. At the other end of the range, I probably wouldn't go over 5k to keep the noise low. When choosing a P2 value, keep headroom in mind. 1+ P2/R2 is the U2 gain, and too much...

I don't see why precision opamps (low DC offset) would make a difference. You can change the C2 value to whatever you like. It just gets multiplied by 1 + P2/R2.

I would actually use a dual opamp in real life. The only reason you see 2x OPA196 in the schematic is that I did it in a simulator and there are no dual opamps there. TL072 ought to work fine, too, if you're not into SMD.

Thank you! I was today years old when I realized, thanks to you, that I could just use a wav file as the input to a circuit simulation (in my case, TINA-TI) and record its output back to a wav file. D'ooooh! Why didn't I think of that?? Who even needs to actually build physical stuff anymore...

I am having a hard time imagining the use case for a balanced in/balanced out pedal, especially one that would need a true bypass. Please tell us more.

I'm afraid I can't help, I don't use LTSpice.

If you want a high input impedance op amp stage, you'll always want to go non-inverting for low noise.

There's no reason for R23 and R36 to be any higher than around 10k. They make noise. The higher the value, the higher the noise. Don't just jumper them, as suggested above, or the circuit won't work at all. In several places, you have RC filters that will significantly roll off the lows (C6-R6...

^ I can't disagree 😛

I have a little concern. In several places, you have 4.7uF caps tied to some DC voltage via 1M resistors. After powerup, those would take quite a long time to find a stable DC operating point, wouldn't they? The time constant is on the order of seconds. Does the circuit work right away when you...

If it does it mostly at startup and it gets progressively better over time, it sounds like a bad electrolytic capacitor to me. Though I must say I've also seen a few op amps do that... If you have some Freeze Mist around, it could help with narrowing down a specific component.