Two tone fuzz

[mybud]

Build Rating

4.00 star(s)

Ok, herewith my first build report for 2026 and a long interval since the last because I’ve been down the modular synth rabbit-hole for the last couple of months. I used a trio of AC128s (Q1 164, 1.284mA, Q2 167, 0.92mA, Q3 118, 0.72mA). After breadboard testing, this particular combination seemed to work best.



Something quite weird happened when I first fired it up in its housing. There was a typical ‘magic smoke’ smell within seconds. I disconnected it and naturally assumed the worst (blown charge pump or diode, AC128s gone west, what have you). Having managed to assemble everything in my initial optimism, I dreaded having to disassemble and troubleshoot the whole shooting match.

I then tested the protection diode and charge pump and got plausible voltage readings and retested the audio, which worked as before. Really peculiar, but no further panics: all working according to plan. Perhaps the pedal gods were trying to amuse themselves at my expense.



How is it? A fairly typical TB but a bit more versatile perhaps. I’m not over-enamoured of fuzz boxes generally but this takes the classic TB a bit further. I think the added bass option is my favourite setting. Else to my ears it’s too raspy and shrill.

I’m going to leave it running all day, just to determine that the weird behaviour above has now truly corrected itself. Wouldn’t want to burn down my workshop inadvertently.

Thanks for reading as ever and best wishes for successful builds to you all.

 

[Erik S]

Are you using any stomp boxes with your modular rig?

 

[mybud]

Are you using any stomp boxes with your modular rig?

Yes. To match signal levels between modular and stomp worlds, I use two of these. Some stomps are more prone to hum and other noise than others. Probably wise to use shielded (ordinary guitar) cables and 1/4” to 1/8” adapters to minimise such issues.

 

[Erik S]

Yes. To match signal levels between modular and stomp worlds, I use two of these. Some stomps are more prone to hum and other noise than others. Probably wise to use shielded (ordinary guitar) cables and 1/4” to 1/8” adapters to minimise such issues.

Nice! Those look perfect. No rack in my rig yet, but I have fought with getting synth signal levels right for pedals.

 

[mybud]

Nice! Those look perfect. No rack in my rig yet, but I have fought with getting synth signal levels right for pedals.

Yeah, they work well and take up very little space (2U, I think). Their purpose is to drop the much hotter synth signal to a manageable level for stomps, so a kind of impedance* matching buffer AFAIK.
*because we’re dealing with AC signals…

My modular rabbit-hole has consisted of systematically breadboarding most of Moritz Klein’s amazing educational module designs (details here). They only do kits, which is a mild bummer (I asked) but the documentation is brilliant for understanding how synths work. I’ve learned so much from his lucid explanations and accompanying demo’s.

In process of considering how to house his 808 snare, which I love, not to mention addressing the challenge of running an offboard +-12V system that can run independently of my main system. It’s quite weird to come back to the ‘simple’ 9VDC world

Sorry, mildly carried away there…

Will report on the 808 progress in due course.

 

[Fama]

Thanks for the transistor values, I need to choose the final transistors for mine still!

I've had two builds where I'm pretty sure I've had actual smoke come out of them (IIRC it might have been transistors that had only 2/3 of their legs in sockets?) but I unplugged them immediately, and nothing was ever damaged. I suspect it might have been some flux or something in those cases that smoked a bit? I don't know, very weird. Maybe yours had nothing wrong since you didn't need to fix anything, some electronics give out a smoke smell on the first power on.

 

[mybud]

Thanks for the transistor values, I need to choose the final transistors for mine still!

I've had two builds where I'm pretty sure I've had actual smoke come out of them (IIRC it might have been transistors that had only 2/3 of their legs in sockets?) but I unplugged them immediately, and nothing was ever damaged. I suspect it might have been some flux or something in those cases that smoked a bit? I don't know, very weird. Maybe yours had nothing wrong since you didn't need to fix anything, some electronics give out a smoke smell on the first power on.

Yeah, I’m wondering if there might have been a spot of Loctite that I applied to secure the DC jack that might somehow have spanned both 9V and ground connections. When power was applied, this might have burned off, hence the smell. Quite weird, really…