Wah pedal buffer circuits?

[Mark Abbott]

I have a Stuart Castledine pcb which is very good. Though the buffer on the end of the wah pedal circuit boosts the level of the signal and doesn't buffer it prior to seeing the Fuzz Face. Thus the wah does work all that well going into the Fuzz Face. I have seen several buffer circuit being FET and IC buffers.

My question is what works best?

Yours Sincerely

Mark Abbott

P.S. I recently downloaded a demo of the Fuzz Factory, I'm not sure I'd use all those sounds, though I couldn't but help think Jimi Hendrix would have much preferred this over the Roger Mayer version. It best suited to someone with imagination, no wonder it is popular with the cloners.

[GibsonGM]

I think it's a matter of taste...FET based buffers might sound more "sparkly" or "tube-like" to some, some prefer IC, some (myself included) like a simple BJT based buffer.   They all do the job, and sound different in differing applications....try a couple and see what you think.  You could always build 1 or 2 on breadboard, and run a short cord from wah to buffer, to fuzz, to see what sounds you get...

[jaytee]

Or a mosfet buffer, like this;

[Mark Abbott]

Dear Jaytee and Gibson GM

Thanks for the replies. naturally the thing that I'm after is an articulate vocal-like tone from the Wah pedal. Do the various buffers do this or are some better than others?

It also occurred to me that part of the joy of the Fuzz Face it that it rolls off high end and thickens up the sound of single coil guitars such as Stats and Teles, thus a buffer could make the Fuzz Face sound a bit too bright.

Thanks again for your advice, I give the various circuits a try and see what sounds.

Yours Sincerely

Mark Abbott 

[Gus]

A wha to a FF is about the output resistance of the wha.

The reason a voltage gain stage after the wha with a volume pot works is often the pot will not be set to max and there is some SERIES resistance along with the output R of the stage  going into the summing node of the fuzz face type circuit.

Remember the FF has two gain stages the first transistor with the feedback R and source Z of the guitar or what is feeding it
THEN  the 2nd gain stage

The output R of the wha is not the same as a guitar

Say you want the first gain stage of the FF type circuit to be about 5.  If you have a 100K feedback R you would want about 20K output resistance (100/20 =5) The first stage is where you get the  "touch control"

The FF its self does not roll off the high end the inductance of the guitar pickup goes up at higher freqs and therefore the first stage gain changes

feedback R / source feeding the ff type summing node input

[Mark Abbott]

Dear Gus

I don't entirely understand everything that you are saying, but that says more about my lack of understanding.

I'm finding that I have a voltage gain stage after the wah with a volume pot (I think) after the gain stage and it isn't working for me at all. In fact it sound much the same as no voltage gain stage at all. Thus the buffer might be the sort of thing I'm looking for?

Regarding buffers and fuzz faces. I use to use a dummy coil and a mixer/buffer in my guitar prior to putting in Kinman's in the guitar. I found the fuzz face not to sound as fat. I put this down to an impedance mismatch between the  guitar and the fuzz face.

Thanks for your help Gus and sorry I didn't entirely get it.

Yours Sincerely

Mark Abbott

[jaytee]

A wha to a FF is about the output resistance of the wha.

The reason a voltage gain stage after the wha with a volume pot works is often the pot will not be set to max and there is some SERIES resistance along with the output R of the stage  going into the summing node of the fuzz face type circuit.

Remember the FF has two gain stages the first transistor with the feedback R and source Z of the guitar or what is feeding it
THEN  the 2nd gain stage

The output R of the wha is not the same as a guitar

Say you want the first gain stage of the FF type circuit to be about 5.  If you have a 100K feedback R you would want about 20K output resistance (100/20 =5) The first stage is where you get the  "touch control"

The FF its self does not roll off the high end the inductance of the guitar pickup goes up at higher freqs and therefore the first stage gain changes

feedback R / source feeding the ff type summing node input

I get you. So something like this would work better?


Has a gain of about 2 so set to unity would have about 25k output resistance. I think the amount of summing would depend on where the gain is on the fuzzface. With gain full up theres no ac negative feedback. The output resistance would work as a potential divider with the input resistance of the fuzzface, which is quite low. It would be interesting to see what the castledine circuit is like.

[jaytee]

Just a thought, depending on how the Castledine circuit is set up, you could just stick a trimmer in series with the output of the wah. Say 50-100k and adjust until it sounds right.

[Mark Abbott]

Dear Jaytee

I Will try and find time to write the circuit up, though I'm fairly sure my demo version of multisim has time expired by now, so my drawing might be a little cruder. 

Oh yeah, I normally have the gain of the Fuzz Face nearly on full. So I dare say there wouldn't be a lot of AC feedback in my circumstance.

Yours Sincerely

Mark Abbott