Foxx Tone Machine question

[Jackie Treehorn]

Hello Everyone,

This is my first post, but I've been lurking!

I built the Foxx Tone Machine from a General Guitar Gadgets PCB and transistors from small bear.  In one position of the octave/sustain switch I get fuzz with octave and in the other, I get basically just the octave sound, very little fundamental.  I'm not getting just fuzzed guitar sound, though.  This is fine with me really.  However, I'm wondering whether this is the standard Tone Machine modus operandi or whether it's a happy accident.  I thought I would get just fuzz and fuzz/octave from the switch. 

Anyway, another odd thing that I mention just in case it's related is that I used a single pole switch to bypass the effect, ie leaving the guitar connected to the tone machine input and switching the output between straight guitar and tone machine output - which results in the bypass still having a lot of tone machine.

Thanks for any help/guidance!

[Herr Masel]

The first thing to look at (from experience) is the bias, which when done badly can sound like an octave effect. I don't know the schematic for that pedal and I don't know what the bias should be but if you post the readings from the transistors I'm sure you'll get some answers.

[MartyMart]

Hi and welcome !
That's quite a big circuit to tackle, so well done
The switch should just turn the "octave" section off and on, leaving
the "fuzz" intact !
I'd check the wiring on and around the switch, also you need at least a DPDT
footswitch to bypass the effect properly which is compounding the
problem/adding to it for sure.
Make sure that the 10uf off Q2 connects to the cathode of the second diode
NOT the anode of the first !
Otherwise the switch wont disconnect the first diode when flipped.
DPDT's are readily available so I'd start there and get back to us.

Cheers,
Marty.

[dv8]

Welcome!

FTM is a monster.  Checkout tonefrenzy.com audio sample, they have a long sample of the FTM.  Yours should be close to what they have there (or at least my FTM clone) is.

And my octave switch goes from fuzz to fuzz+octave.  Maybe you discovered a mod.

-brian

[Jackie Treehorn]

thanks for the help!

I checked it over, and tried some different settings.  Perhaps I was a bit off in my initial 2 am trouble shooting.  I think the fuzz just has some kind of even order harmonics that I mistook for the octave effect.  I took it to rehearsal and at volume into an already distorted amp it seemed to be operating normally.  I'm definitely getting a double pole switch for the bypass, though! 

A very cool effect!  Great at annoying the band members.  I kind of expected it to be a bit more gritty.  Any tips to accentuate the nastiness?  Ceramic caps perhaps?  I've got germanium diodes in there now, I was thinking of swapping the pair of reverse diodes in the non octave section with silicon.  Do you think it would make a difference?

[MartyMart]

Glad to hear that it seems "OK"
Two points :
First, since the first "pair" of diodes are creating the octave
you'll have a better and clearer octave note if they are "matched"
( perhaps you did this anyway? )
Take your DMM, which should have a -->l--  diode tester on it
check through a few diodes to get a matched forward current reading
let's say you find two reading 0.32 v  ...... bingo !

Second, try leaving the two Ge's in circuit and adding one Si, such as
1N4148 in one direction, you'll then have some more clipping and it
will be assymetrical, richer IMHO and a bit nastier !!
Reducing the 1k resistor off Q3's emitter may get you some more
gain, try 470 ohms or 220 ohms ( not 100% sure of this )

I did this with a Univox superfuzz and it sounds FAB 

Marty.

[Plexi]

Glad to hear that it seems "OK"
Two points :
First, since the first "pair" of diodes are creating the octave
you'll have a better and clearer octave note if they are "matched"
( perhaps you did this anyway? )
Take your DMM, which should have a -->l--  diode tester on it
check through a few diodes to get a matched forward current reading
let's say you find two reading 0.32 v  ...... bingo !

Second, try leaving the two Ge's in circuit and adding one Si, such as
1N4148 in one direction, you'll then have some more clipping and it
will be assymetrical, richer IMHO and a bit nastier !!
Reducing the 1k resistor off Q3's emitter may get you some more
gain, try 470 ohms or 220 ohms ( not 100% sure of this )

I did this with a Univox superfuzz and it sounds FAB 

Marty.

Great advise.
Thanks! (12 years later  )

[bluebunny]

Great advise.
Thanks! (12 years later  )

A little late on two counts.  Sadly, Marty left us a few years ago.   

[Plexi]

Great advise.
Thanks! (12 years later  )

A little late on two counts.  Sadly, Marty left us a few years ago.   

Oh....

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