SOLVED Unintentionally gated Ge Fuzz Face

andare

Well-known member
I built this germanium Fuzz Face for a friend. It's my first commission so of course Murphy's Law decided to apply. After boxing it up it started to sound gated with a farty cleanup.

The circuit worked perfectly on the breadboard so I built it on eyelet board. Here it is powered by a 9V battery through my Auditorium and alligator clips to connect the pots, working as intended:


The circuit is stock except for a 220nF input cap and a A250k volume pot to make it less woofy. I have an issue with Fuzz Faces and Tone Bender MKIIs I build, they all have flabby low end and they lose attack on the low strings, especially on the neck pickup. No idea if it's the transistors I have on hand - ASY33 and ASY34. Those two mods take care of the issue without changing the basic tone.

I built a voltage inverter using the following schematic. I've used this before without issues:

Screen Shot 2023-07-16 at 10.17.22.png

With my power supply I get these voltages:

DC Jack 8.99V

TC1044SCPA Pins:
  1. 8.94V
  2. 5.15V
  3. 0
  4. -3.63V
  5. -8.75V
  6. 4.03V
  7. 5.48V
  8. -8.94V

Transistors:
  • Q1b -0.12V
  • Q1c -0.68V
  • Q1e 0

  • Q2b -0.68V
  • Q2c -4.93V
  • Q2e 0
Those seem ok to me. Pretty sure Q2c was a tad lower on the breadboard but a higher voltage should make it sound brighter and tighter, not darker and gated. Generally Ge FFs sound pretty much the same to me between -4V and -5V.

Gutshots:

20230714_171211-01.jpeg
20230716_104303.jpg

Ugly but everything checks out. I get continuity where expected. I used the DC Jack breakout board for cleaner connections to +9V and ground. The voltage inverter is on two layers of double-sided foam tape. I thoroughly checked it for shorts and bridges while building it.

The board is mounted to the enclosure with the two bolts you see. There are 5mm plastic spacers on the bolts to give clearance to the wires under the board. The left bolt is grounded, the right one isn't. I guess it doesn't make contact with the raw enclosure. The empty eyelets are isolated.

Bending the transistors around doesn't change anything.
Since the circuit worked on the board before boxing it up, the problem must arise from the wiring or voltage inverter.

I hope I have provided enough information. I appreciate any help you can offer. Even just the theory of how and why a fuzz might gate would be useful for future builds.

Thank you,

Andre
 
It’s fun. Also, I edited my above comment…
The pots aren't touching anything. Also wouldn't that simply lower the volume overall? I don't understand what happens at the end of the taper to lower the volume instead of raise it.
Must be something super silly I'm overlooking :)
 
The pots aren't touching anything. Also wouldn't that simply lower the volume overall? I don't understand what happens at the end of the taper to lower the volume instead of raise it.
Must be something super silly I'm overlooking :)

Ground outs can make all sorts of weird stuff happen…
 
I ran the pedal through my solid state bass amp (fender Rumble 100) and the issue is not present. Same thing through my audio interface (Scarlett 2i2).

So the problem only exists with my tube guitar amp. Weird because none of my other fuzzes do that.
 
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I ran the pedal through my solid state bass amp (fender Rumble 100) and the issue is not present. Same thing through my audio interface (Scarlett 2i2).

So the problem only exists with my tube guitar amp. Weird because none of my other fuzzes do that.

A SS amp has near way more headroom than a tube amp. Your results suggests to me that your out out is too hot…it’s completely overwhelming your tube amp. Do you get the same results with the volume control turned down?
 
A SS amp has near way more headroom than a tube amp. Your results suggests to me that your out out is too hot…it’s completely overwhelming your tube amp. Do you get the same results with the volume control turned down?
Yes, amp Gain and Master are barely on, the Clean/Drive toggle is set to Clean (blackface mode) and the volume drop and gating happen after 3 o'clock on the Fuzz Face Volume knob.

I have another Fuzz Face that is even louder because I used a 2k2 resistor instead of 470R but that one works normally.
 
I have another Fuzz Face that is even louder because I used a 2k2 resistor instead of 470R but that one works normally.
Did you compare the HFe's? I think that might affect the volumes too. Unless you're A/B'ing them and the second one is clearly louder.

Different frequency balances can also affect signal "strength" so to say, bass frequencies have more energy than higher frequencies, so something might sound louder while the signal could be lower when measured. Although I think you mentioned that this one should have less lower frequencies, so it should be sort of the opposite, maybe.

But if it works fine with the solid state amp, that explanation seems to fit all the facts at least.
 
Both are pretty much hfe 80/120.

I took it over to my friend and through his 60w music man amp it sounds unbelievable, better than through my amp, and it works perfectly. So he bought it.

Clearly you guys were right, somehow this fuzz, despite being quieter than the other one, overpowers my 30w amp.

I'll pay attention to this issue in the future.

Thanks everybody who contributed to help me!
 
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