Fender Fuzzwah - Fuzz Only Schematic

[cps]

Hi,

One of my favourite pedals is the 70s Fender FuzzWah with the three control pots (see here http://www.effectsdatabase.com/model/fender/fuzzwah/2).

I've actually got one of these pedals - I really like the distortion however the pedal weighs a ton and the wah is really scratchy.

I was wondering how difficult it would be to separate the fuzz circuit from the wah circuit - by this I mean, creating a schematic of just the fuzz part of the pedal so that I could build a fuzz-only version. Would this be easy/difficult/impossible?

Here's the schematic I'm interested in:

http://www.labyrinth.net.au/~cpsmusic/fender_fuzz-wah-pedal.png

I have some knowledge of electronics but I'm no guru!

Cheers,

Chris

[petemoore]

  The Fuzz portion is outlined by all the connections which somehow connect-through-parts to the Fuzz switch input and output lugs.
   The non-Fuzz [wah] portion includes all the interconnects between the wah input and output lugs of the wah switch.
   Signal into a correctly wired fuzz-portion + the ground and power supply requirements should allow a working Fuzz-Only circuit.

[cps]

Thanks, I'll give it a go.

[cps]

I've had a go at trying to trace out the fuzz component of the circuit however the op amp section seems to be part of both the fuzz and the wah circuits. I'm not clear how to separate the two - some help with this would be very much appreciated.

Cheers,

Chris

[cps]

I've been doing some research on the Fender FuzzWah schematic and looks (to my beginner's eye) a lot like a Rat - is that right?

[Gus]

Simmed using stock LT spice download.  Q1 is a phase inverter

Use a TL071 etc.  Interesting fuzz with the mix control

[cps]

Many thanks for the schematic. I'm going to have a go at building one of these in the next few weeks.

Cheers,

Chris

[cps]

I have another question regarding this circuit - does the particular opamp, transistor and diodes used make a difference to the sound? That is, should I try and get the original components or can I substitute with more modern equivalents?

[John Lyons]

Take a closer look at the schematic.
Gus has given you your answer. 
You should try silicon (as shown) and germanium diodes
to see which you like best.
The circuit is similar to many op amp diode to ground
clipping circuits. Rat included.The main difference is the
clean blend feature.

[soggybag]

The blend feature is pretty interesting, I haven't seen this before in a Fuzz/Distortion. Really it's blending the inverted signal. Oops! wait that's an inverting op-amp! So really we're blending the inverted signal with the inverted signal. So the output is inverting.

I kind of want to hear it with a non-inverting op-amp stage...

[cps]

Yes, I can see that new components have been substituted for the ones that might be hard to get now. I'm curious as to how much difference this will make (maybe it's only possible to tell if there's a difference by building it?).

Another question, in the original schematic the clipping diodes aren't identified. Is it possible to work out what they are? If so, would I need to remove them from the pcb?

Cheers,

Chris

[Gus]

Q1 should not matter much if at all
Search the web or look in books for the opamp or try a 741, TL071, LM351 or 1/2 of different duals like a 1458, 4558, TL072 etc
You can measure the diodes to tell if Ge or Si.  I guessed 1n4148s because there is a volume control after them and a mix control after that.

[chavette]

Hey there !

My Fender Fuzz Wah Op Amp CA1458I just fried (because of a reversed alimentation  )
Does anyone knows where I can find these ?
Don't want to loose the original tone of my favourite pedal !

THanks for your help