Buzzy Pro-10 Blue Overdrive

[Svenson007]

Hey there guys!

So I built a Pro 10 Blue overdrive (single not dual) pedal for somebody all the way in Switzerland. I’m in Canada. He loves the overall overdrive sound (like reeaallyy loves it) But is disappointed because he is getting what he describes as a low mosquito type buzzy sound in the background that floats in and out of the sound. He sent me a bunch of audio clips that I will include.
At first I couldn’t tell what he meant. It took multiple listens to hear it. It’s a buzzy sound that floats in and out. Kind of similar to a snare drum in the same room.

He sent me a hundred pics of everything and there isn’t anything wrong that can be seen through visual inspection. I’m thinking maybe it’s one of the opamps. I used a very old TLO71 and it’s just my suspicion that it maybe causing the problem. Almost like it’s not biased 100% type sound. I think I mistakenly missed this sound during testing.

I’m pretty sure I was just playing your standard riffing kinda music. I strummed some chords and listened. Everything seemed like another successful Pro 10 Blue build. He plays more quiet ambient type music so it became apparent. All I remember is it sounded like a successful build and shipped er.
I know it’s a long shot here guys. But here are some files to listen to. There are a couple where I can’t really hear the problem.

Unfortunately he lives in the middle of nowhere in Switzerland. I offered to pay for somebody to check it out/fix it… but he can’t think of anywhere he could take it. I’m wondering if I could send him some new opamps and coach him through swapping them. But I’m not sure he’s capable.


Anyways thanks for musing me if you are still here and give the clips a listen. Cheers

Pedal - Google Drive

drive.google.com

 

[Cybercow]

FWIW, I found that "iffy", b-stock, otherwise bad TL072CP opamps tend to exhibit that same annoyance. They tend to "fizzle" on the release portion of signal transients.

After listening to your demos, I get the impression it's the opamp(s).

I found a few dates codes of known bad TL072CP opamps (all came from Tayda):
18MDSHY
14AP8NM
07A5L8QM
22ALE3M

The fix I found was to get some TL072IP opamps from Cusak (StompBoxParts). When I replaced all the TL072s in did a short run of 5 Kliche builds, those "fizzy"tails went away.

Just sayin'.

 

[Svenson007]

FWIW, I found that "iffy", b-stock, otherwise bad TL072CP opamps tend to exhibit that same annoyance. They tend to "fizzle" on the release portion of signal transients.

After listening to your demos, I get the impression it's the opamp(s).

I found a few dates codes of known bad TL072CP opamps (all came from Tayda):
18MDSHY
14AP8NM
07A5L8QM
22ALE3M

The fix I found was to get some TL072IP opamps from Cusak (StompBoxParts). When I replaced all the TL072s in did a short run of 5 Kliche builds, those "fizzy"tails went away.

Just sayin'.

Thanks for taking the time man. Yeah that’s sort of what I suspected. Think I’ll stick to Mouser for chips and tayda for other stuff from now on. Although I’ve had pretty good success, I always knew there is a risk in ordering B stock. I can’t believe I didn’t hear this while testing. Maybe it was just what I was playing didn’t allow me to hear this. I’ll defiantly be listening harder from now on. I had to test 9 pedals that day pretty quickly.


Someone just rockin out garage rock probably wouldn’t have even heard it haha.

Anyways I hope I can send him some fresh chips and coach him through swapping. He is very electronically naive, and a bit spooked to touch anything. Btw thanks for the part numbers.

Cheers