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Buffered ABY works best unpowered

Started by Jmeasterling, November 05, 2016, 06:11:09 AM

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Jmeasterling

Hi. I'm new. New to building my own pedals anyway. I've modded my guitars since the first, but that's not much circuitry...

I built an aby box following Breja toneworks plans
( https://youtu.be/f7Y8Qm1aOCI ) and built 2 of the buffer circuits mapped out by DIY Guitar Pedals ( https://youtu.be/dMxwT7BT7oE ) I took pictures as it went. It's not the cleanest of installs, but it is my first. The pedal works great, splits channels with no signal loss, runs both channels with no drop out, UNTIL I give the pedal power. It's powered so the LEDs will light telling what channel is in use. without power, it's great, but when powered, if on A or B there's a terrible, pulsing buzz... like a ground fault. Channel Y is silent until I roll the guitar volume on, and same sound... A and B respectively make the hum without volume from the guitar, but Y only hums WITH guitar volume. The breja schematic includes a ground lift, which I put in, but it makes no change when switching it on or off. I ran a 9v battery to the power jack with alligator clips and even tried reversing the positive and negative, in case I had gotten a positive center pin jack, but to no avail. I bought decent quality parts from Mouser and Pedal Parts Plus... Any ideas?

Thanks in advance for glancing at this

Muadzin

Hmm, I'm not a big fan of 'solder everything together without a board' as shown in those DIY Guitar Pedals vids. Too much chance of something going wrong in my opinion. Especially for a newbie. And methinks in those 2 buffer circuits you have the biggest chance of something having gone wrong. I would suggest remove those and see if the pedal works as according to the original Breja toneworks layout.

Also, where in the signal chains are the two buffers exactly placed? I take it just before the two outputs, right?

m-Kresol

I'm a bit confused by the fact that your opamp buffer is working without supply voltage. I might be wrong, but I thought those need power to even start working.
I build pedals to hide my lousy playing.

My projects are labeled Quantum Effects. My shared OSH park projects: https://oshpark.com/profiles/m-Kresol
My build docs and tutorials

Jmeasterling

@muadzin, yes, both buffers are between the switches for each split and the output jacks for each, powered and grounded... So I dunno... I'll try taking them out and see what happens...

@m-Kresol, I know right.... As I mentioned above, I may try removing the buffers and see what's what... I didn't overheat anything soldering, and made sure nothing is touching that shouldn't be... I put a dot of hot glue between things that COULD potentially touch...

I had thought of using Veroboard, but this seemed simple enough without... But ya know, it's all a learning process...