Author Topic: Fuzz Face volume problem  (Read 675 times)

mateusborges

Fuzz Face volume problem
« on: November 16, 2021, 09:01:07 PM »
Heyas!

After almost losing the battle against the germanium, I finally did it!

My 1st positive ground fully working Fuzz Face... well, not fuuuully working.

Here's the deal, volume pot aren't working as it should, I mean, it's working but I can't get it to actually zero the volume, actually, when turned to zero it's still pretty loud. I tried checking everything I could, measured eveything, all connections and values but I just can't find what I'm doing wrong and I've been about 3 days around this guy ><

It sounds great, cleans great with guitar volume pot, but it's kinda noisy, I mean, I've heard some that sounds as good with less noise.

Since, I'm a slow learner, and a noob, lemme show everything I got and how I did it.

My germanium are PNP, Q1 measures 69 hFE (perfect number btw) and leaks 180 mA, Q2 measures 118 hFE and leaks 213 mA. All measures took using GeoFX gizmo (btw, thanks for sharing all the knowledge and love put into your research), got a trimmer to set the 2.472 R resistor and made sure not to touch the germs for about 15 mins before each test, those numbers are an average of 3 tests.

Fuzz is a B1K pot, bias is a B10K pot and volume is a B500K pot, I have no log ones around (please don't tell me this could be it. Anyways, it measure from open to 498K correctly). Bias pot allows me getting Q2 collector voltage between ~ -1.5v to ~ -7v or something like this. Power supply measuring perfect 9v.

Used Nichicon axial caps for the 22 and 2.2 uF, an MKT film 10 nF and metal film resistors.





And now please don't blame me, I've tried! hehe
Here's my connections, one by one.



Any ideas or suggestions?

Cheers!
« Last Edit: November 16, 2021, 11:52:13 PM by mateusborges »

idy

Re: Fuzz Face volume problem
« Reply #1 on: November 17, 2021, 12:07:35 AM »
Most likely the volume pot is not grounded properly. Maybe it looks good, but is loose under the solder etc. Check thoroughly. Resolder the ground at both ends. Measure continuity from volume pot terminal 1 to ground.
I suppose also (barely) possible that pot is bad and terminal 1 is not even attached to the "wafer" inside. You already checked for 500k from terminal 1 to 3, so that's not broken..
« Last Edit: November 17, 2021, 12:32:08 AM by idy »

antonis

Re: Fuzz Face volume problem
« Reply #2 on: November 17, 2021, 05:45:56 AM »
What idy said..  :icon_wink:

With lug 1 "open", Vol pot acts as a variable resistor with next effect input impedance formed voltage divider..
e.g. for amp 1M input impedance, when pot set FCCW (theoretically zero output) practical next effect input signal is 66% of FF output amplitude.. 


P.S.
You unintentionally built an input impedance meter.. :icon_lol:
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

mateusborges

Re: Fuzz Face volume problem
« Reply #3 on: November 17, 2021, 10:53:52 AM »
Thanks!

Gonna check tonight.

Cheers!

mateusborges

Re: Fuzz Face volume problem
« Reply #4 on: November 17, 2021, 07:03:18 PM »
Yeah, the pot is missbehaving it seems, I need to stop being so cheap...
I blame economics tho.

Gonna change it for another cheap pot hehe and report back.

pinkjimiphoton

Re: Fuzz Face volume problem
« Reply #5 on: November 20, 2021, 03:18:51 PM »
you really want a log pot for the output. 100k to 500k will all work, tho the smaller the pot, the less output slightly.
a linear taper pot will work exactly as described... too loud for the volume.  an audio taper spreads it out a bit more.

check the ground connection to the volume pot.
  • SUPPORTER
"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!

mateusborges

Re: Fuzz Face volume problem
« Reply #6 on: November 28, 2021, 12:49:00 AM »
Guess what, the pot was damaged ><
Got a 500k log this time and itís all sounding gorgeous!

Cheers!

pinkjimiphoton

Re: Fuzz Face volume problem
« Reply #7 on: November 28, 2021, 12:55:33 PM »
Guess what, the pot was damaged ><
Got a 500k log this time and itís all sounding gorgeous!

Cheers!

i knew you'd get it bro!
  • SUPPORTER
"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!

mateusborges

Re: Fuzz Face volume problem
« Reply #8 on: November 28, 2021, 07:33:10 PM »
Final build.

Ty all guys, lots of people and I hope you know who you are! Almost 10 pedals now :)
Time for something new.





Cheers!