Fuzz face clone with bias control

[Spencerleehorton]

Looks like a couple of polypropylene caps in the prototype, one has 2.2k on it which I would think could be a 2.2uf, the other looks like it could say 3.0k which maybe 3uf ?
Looks like a silver tantalum near the output on the right? No idea what value.
A couple of black looking components which could be old school electrolytic? Could be the 10uf?
Top right I can see a couple of old diodes.
Can’t see the small 33pf or the 100pf caps?
On the outside of the case there are big electrolytic caps but I believe these to be power caps on the psu.
I count 11 resistors in the prototype but only 7 on the schematic?
4 pots which seems right.

 

[Spencerleehorton]

Well fired up the west coast fuzz with 2 x nkt275 and one ac128 in Q3 and to be honest it doesn’t sound that great at all, tonally not great and not much fuzz, will try with the other transistors and see if it improves?
The JH-2 fuzz is pretty gainy, lots of fuzz, but too harsh but I’ll try the mods suggested now and see if it improves, definitely some scope with this one tonally just need to reign in the top end.

In my mind the expandora is still out in the lead but it’s not really a fuzz more of a distortion.

 

[Spencerleehorton]

next step is to check all voltages along with this info:

I set the bias trimmer fully clockwise and then set the 9V power on(yes there is no 2M and 40k potentiometer on the board, it do NOT matter for now). measured the Q2 Transistor Collector Voltage(using q2c, see picture below for test point location) i tried different zener until i got to around 3V.

Diode that worked for me was the 5.6Volt Zener and removing the 1N4148 Diode(using a wire jumper instead)
Now you can process to install/solder the potentiometers and the rest of the components on the board
For my own unit this is the transistor and bias setting that worked.

• Q1C = 0.46V, HFe = 80, Leakage = 166µA
• Q2C = 4.03V, HFe = 67, Leakage = 89µA
• Q3C = 7.59V, HFe = 67, Leakage = 113µA
• Bias Supply - Bias supply voltage = 6.09V
• Bias OUT - Bias with 5.6Zener and no 1N4148 = 1.59V

ive used a 5.1 zener , so i'll see where im at and maybe take out the 1N4148 and see what happens!!

 

[Spencerleehorton]

well any help would be appreciated but as per the cap values, im working from a picture, i dont have the actual unit to test, and yes i already have a capacitor tester.

 

[13engrsapper]

When it was built, did it actually sound like the one with knobs, or did you have to tweak it some more?

Probably 15-18 years ago or more

 

[Spencerleehorton]

have started to put everything into LTspice and check it out, came across this cicuit and wondered if it was correct as output seems strange?

output in red input in blue

 

[Spencerleehorton]

Built this P2P fuzz with 2n3906 and ac128, sounds really nice doesn’t seem to bottom out like a traditional FF.
Still trying to get the wah first in line and then the FF working, have tried the 10k resistor trick on the output of wah but don’t seem to work that well?
Will try building a few buffers and see if they work any better.
This fuzz has a 250k trimmer on the input but doesn’t seem to work well either?
I’ll try setting it to 10k and see if it’s any better!!
And yes there is a mistake in the picture which you may spot!!
I’ve have corrected!!

 

[Spencerleehorton]

The 10k on the output of the wah doesn’t work with Dallas arbiter FF or the new Fuzz with silicon and germanium?
So I’m going to have to make a buffer for it.
Fox Rox buffer seems the way to go so I’ll make one and see, anyone else have any ideas on a simple cheap buffer which works with original FF low impedance circuits?

 

[Spencerleehorton]

When talking fuzz it’s hard to not check out what roger Mayer is doing, I’ve only just seen this Visage pedal!!



Interesting

 

[Spencerleehorton]

Seen a few pictures and it only seems to consist of 8 resistors, 2 x transistors, 4 ceramic caps, 3 x film caps, 1 x diode and 6 electrolytic!
The 4 ceramics are selectable I’m assuming for different attenuation of top end?
The 3 x film (looks like 10nf, 100nf and 1uf?) I would expect they are selectable and alter the mid/bottom end?
And the 6 electrolytic seem to have one as either 100uf or 220uf for the power rail for smoothing.
There are 3 electrolytic which look like values 2 x 22uf and 1 x 47uf?
Transistors have BC550c written on them.
Resistor values that I can see are
47k, 1M, 100k, 2 x 220R, 4.7k and 2x 10k.
Pot wise it is a 47k log and a 2k lin.
Haven’t seen a fuzz using the bc550c before?

 

[Spencerleehorton]

Here is the picture of the pcb

I’ve got a feeling that the resistor above the 220R resistor by the diode is not a 220R and maybe a 2.2M?

 

[3rdToneFromTheSun]

When talking fuzz it’s hard to not check out what roger Mayer is doing, I’ve only just seen this Visage pedal!!



Interesting

Hello, I have that, and it is monstrous!!

Coincidentally, I found you via the Dave Weyer thread on Metropolous, then here, and then on Instagram hahaha - I have sent a message (from @3rdToneFromTheSun) regard the West Coast Fuzz as I am seemingly in pursuit of it!?

 

[Spencerleehorton]

Hello, I have that, and it is monstrous!!

Coincidentally, I found you via the Dave Weyer thread on Metropolous, then here, and then on Instagram hahaha - I have sent a message (from @3rdToneFromTheSun) regard the West Coast Fuzz as I am seemingly in pursuit of it!?

Yes I’m trying to build that one but got distracted by this RM visage!!
Think I’ve worked out the circuit now but would be nice if someone could trace it out

 

[Spencerleehorton]

this is my best guess so far with the RM visage, just havent found a place for the 1meg resistor!!!
havent got a clue what the park pins part is as well?

 

[Spencerleehorton]

Got a funny feeling the park area is just so you can put the links in there when not needed, that would make sense anyway.

 

[Voyager10]

have started to put everything into LTspice and check it out, came across this cicuit and wondered if it was correct as output seems strange?
View attachment 126550
output in red input in blue

What you are probably seeing is the effect of C9 charging up to its steady-state value. LTSpice will start with all capacitors discharged, so the analysis starts as if at the moment power is first applied.

You can let the simulation run for longer until it settles down, then use the Tstart parameter to skip past the initial part of the sim (e.g. stop time = 100ms, start time = 90ms).

 

[Spencerleehorton]

What you are probably seeing is the effect of C9 charging up to its steady-state value. LTSpice will start with all capacitors discharged, so the analysis starts as if at the moment power is first applied.

You can let the simulation run for longer until it settles down, then use the Tstart parameter to skip past the initial part of the sim (e.g. stop time = 100ms, start time = 90ms).

That’s very helpful thank you

 

[Spencerleehorton]

well my west coast fuzz simulation is looking very nice, now i actually know what im doing with the biasing of the transistors and have some low hfe, low leakage trannys, i will revisit the circuit with my new knowledge.
its looking like an absolute sustain machine!!!!!

 

[Spencerleehorton]

Made the roger Mayer visage today and it sounds great!! I’ve put some 3 way switches for the different caps, going with 220pf, 330pf, 500pf for the top end.
Mid/low going for 10nf, 22nf, 47nf.
Bottom end 2.2uf, 22uf, 47uf or 100uf.
Looking at the simulation it’s very sawtooth waveform where the west coast fuzz is square wave.

Also I’ve finally solved the wah into fuzz problem with building the fox Rox buffer, sounds really good now!!!!

 

[Spencerleehorton]

Got the west coast fuzz going!!

Really like it!!