Fuzz Foundry produces insane squeal - video in comments

[PoppaAdat]

So I just wired up my first pedal, a Fuzz Foundry, and it squeals uncontrollably. It passes a signal just fine and turns on as expected, but I can’t even turn the volume up past 1 before it gets like 10x louder than my amp volume. I can produce a quiet version of a fuzz sound at about 0.5 on the volume but turning the other knobs makes crazy noises and there’s a constant tone/noise when I’m not playing anything. Turning the knobs definitely has an effect on the tone. Also when I first plugged this in, I could hear a radio signal but I wasn’t able to recreate that for the video. So possibly there’s a grounding issue among other things.

I sourced most of the parts from Tayda but the AC128’s I couldn’t find anywhere in the States for an affordable price so I got two off eBay from Sri Lanka I think. I haven’t tested them bc I don’t know how. My soldering is still a work in progress but as far as I can tell, everything appears soldered correctly...nice and shiny. There are very few parts and I was meticulous with my organization when populating the board so it would be unlikely I have wrong parts or components out of order. But of course I can’t rule that out.

I’m hoping this is a common occurrence and easily diagnosable. Any info is greatly appreciated!!!

Here is a link to a video:

Here are some pics of the guts:

 

[Robert]

Sounds like it's working properly. Does the oscillation stop if you turn the Stability knob all the way up?

 

[PoppaAdat]

Sounds like it's working properly. Does the oscillation stop if you turn the Stability knob all the way up?

The stability knob all the way up makes the high pitch tone go away, however there's still an underlying static present. And the weird thing is that when i turn down the volume knob on my guitar, the static becomes very intense the more the guitar is turned down.

Also there is a HUGE volume disparity between my bypassed tone and the pedal being engaged. It's almost to the point where I can't turn it up at all.

Do you have any other ideas I can try? I think the stability knob helped but there's definitely something larger that's wrong about it. I would be happy to post more videos if you think it would help diagnose the problem.

 

[PoppaAdat]

Ok actually I was able to get a usable sound with these settings:
But as you can see everything is either dimed or at zero so it’s not very versatile. I’m guessing this eliminates the hissing sound because the gate is all the way up. If I turn that down even a little though it starts feedbacking like crazy.

I didn’t remove the paint inside so I’m wondering that’s causing some grounding issues? And maybe this pedal is intrinsically just a very finicky design?

 

[Dali]

Built a Deluxe one last week and it's quite a difficult pedal to work with.

Very different reactions from guitar to guitar...

 

[zgrav]

it is a bit of the wild wild west with this one. fun to turn the dials for some different sounds here and there, but a bit of a dice roll on what happens each time you change something. do you get more usable settings if you dial down the volume on your guitar a bit?

 

[PoppaAdat]

it is a bit of the wild wild west with this one. fun to turn the dials for some different sounds here and there, but a bit of a dice roll on what happens each time you change something. do you get more usable settings if you dial down the volume on your guitar a bit?

I wouldn't say I get more usable settings with the volume knob rolled down, it's just completely different sounds. It almost becomes a treble booster on roids with the guitar volume between 5-8. Never had a pedal that responded this much to the guitar's volume controls but I do think it's pretty cool the more I mess with it. However, if I turn the volume knob ALL the way down, it feedbacks like crazy...which could be useful if I had some kind of compressor/limiter. I need to try this on some other amp-guitar combos to hear the full range.

 

[Chuck D. Bones]

Ok actually I was able to get a usable sound with these settings:
But as you can see everything is either dimed or at zero so it’s not very versatile. I’m guessing this eliminates the hissing sound because the gate is all the way up. If I turn that down even a little though it starts feedbacking like crazy.

I didn’t remove the paint inside so I’m wondering that’s causing some grounding issues? And maybe this pedal is intrinsically just a very finicky design?

You definitely need to scrape the paint inside around the holes. Make sure the transistor heatsinks are not touching anything, including each other. Check out the Fuzz Factory manual at Zvex, it will help with settings. I experimented with a Fuzz Factory on a breadboard not too long ago and my experience was there are a lot of combinations of settings on the Fuzz Factory and most of them sound like . The tone is very dependent on the guitar's pickups and control settings. There is significant variation in leakage and hFE with Ge transistors, so you could build five of these and they'd all sound different.

 

[PoppaAdat]

Thanks for the reply! Do I need to remove paint around all the holes or just the inputs?

Also what do you mean by transistor heatsinks?

 

[Chuck D. Bones]

In & out jacks, pots & switches. Basically everything except the power jack & LED.

That big aluminum block with the hole in it is a heatsink. AC128s come two ways. The one on the right has a heatsink pressed on over the transistor case.

 

[PoppaAdat]

OOOhhhhh gotcha. Yeah one of those is touching the bottom of the enclosure. I put electrical tape over the area that touches it (on the enclosure part) hoping that would work. Do I need to bend them more so that they aren't touching anything at all?

 

[Chuck D. Bones]

Yes. Shortening the leads is a good idea too. I'd be inclined to bend them over toward the stomp switch end of the box. Put some insulating material between the heatsink and the board. As an example, here's a pic of a Skreddy Screwdriver I built on a Madbean board using an AC127. Those film caps support the transistor and keep it from touching anything conductive. I prefer them without the heatsink, but we get what we can get.