fOXX Tone Machine Mods?

[DBDbadreligion]

Hi,

My most recent and successful build was the GGG fOXX Tone Machine.
It's a great sounding pedal.  The fuzz is alright but I wish it was a little more fuzzy.
Like say how the fuzz on the Fulltone Ultimate Octave sounds.
Are there any cool mods for the fOXX Tone Machine?  Are there any mods I could do to
make it have a fuzzier fuzz?

Thanks Alot,

Nick

[DBDbadreligion]

bump

[Rodgre]

I don't think I've ever seen any specific mods for the FTM, but I've experimented with different bipolar transistors and different clipping diodes to get different tones. I'm not 100% sure, but I think I settled on 2N5088s and 1N4001s. That's an easy place to experiment.

Also, if you find the schematic for the Prescription Experience pedal, you will see that it is a Tone Machine with the extra "swell" circuit appended to it. Essentially, you could build the "swell" fuzz circuit in another enclosure and run it in series after the Tone Machine to get the same effect. That's how the Experience is wired: Tone Machine with Octave and Bypass switch, extra swell circuit bypass (it is wired so it will only be engagable if the octave is on, using half of the Octave DPDT switch in order to allow the swell circuit to be an option).

Roger

[DBDbadreligion]

ok so if I change the diodes to 1N4001s, what will that do to the sound?  what will the 2N5088s do?

[Mark Hammer]

The diodes in the FTM will alter the tone of the fuzz aspect but not the octaving itself.  Changing D3/D4 ( http://www.generalguitargadgets.com/diagrams/ftmsc.gif ) from germanium to silicon type would result in a much hotter output and a bit less sizzle to the tone.  Do try and maintain the use of Ge types for D1/D2, though. 

Changing the transistors to 2N5088 may or may not make any predictable change to tone.  It depends on what 2N5088s you use and what you have in there or would have used instead.

The octaving in the stock FTM and all its clones (e.g., Danelectro French Toast) is treated as an all-or-none element.  There is no reason I can think of why you should not tinker with in-between settings.  So, for instance, instead of a simple on-off toggle for octaving, you could consider a 1M variable resistor, or perhaps a multi-position toggle or rotary that selected some resistance/s between open (infinite R) and closed (zero R).

Another wacky idea might be to replace R9/R10 with 47k or 51k (better) fixed resistors, and instead of running them directly to ground, run them to the outside lugs of a 100k linear pot, and the wiper of that pot to ground.  When centred, you have the normal 100k-a-side resistance to ground, and when off-center you'd have other octave/fuzz balances and tones.

Finally, the tone control of the FTM is a mélange of several known tone circuits, and I've never been certain it was the best possible tone circuit for the pedal.  When R20 is rotated all the way over so that the wiper is nearest the C10 side, the circuit is essentially a variant of the midscoop that one sees on so many Superfuzz type pedals.  As the tone control gets rotated away from C10 you get a woolier Big Muff kind of sound comprised primarily of the low end, and as you rotate it towards C10 you get the more nasal tone, though never as piercing as a BMP.  If you are a fan of the BMP control, it would not be improper to insert it in there instead of the stock control.  On the other hand, if you lie the action of the FTM control but wouldn't mind a little more flexibility, it would not be improper to consider toggle adjustment of the cap values in there (C11 for notch location and bass '"heft", C10 for midrange bite).

[DBDbadreligion]

so when u say changing to  d1 and d2 diodes it will take sizzle out of the tone.  what does that mean?  does that mean highs?  Will changing those diodes make any more fuzzy?  Like say a fuzz face or a Fulltone Ultimate Octave?

[Mark Hammer]

Diodes with lower forward voltages will clip in response to lower signal amplitudes.  Since your picked string starts out at a high amplitude and declines in amplitude thereafter, that means that the signal will continue to be above clipping threshold for a while longer over the lifespan of the note when you use Ge diodes. 

The trick is to stop thinking of guitar signals as being like steady-state signal generator outputs.  Guitar signals keep changing, and sometimes they're hot enough to clip, but other times they're not.  Using a diode with a higher forward voltage (1N914, LED,etc) means that a smaller proportion/percentage of all those little scope squiggles embodied in the note will be tall enough to bang their heads against the diodes.  In practical terms, the note will clean up faster after you pick with Si diodes, and stay dirty longer if you use Ge.

[DBDbadreligion]

so then I probably shouldn't change the diodes.

[Mark Hammer]

If you want it fuzziest, no.  If you want it loudest, yes.

[DBDbadreligion]

well i went out to radioshack anyway and go the 1N4001's just so I can see how it sounds.  Maybe I will like it.

[Mark Hammer]

Good attitude!

[DBDbadreligion]

ok i tried exchanging D1 and D2 for the 1N4001's, i didn't like it at all.  So i changed it back to the germaniums.  now for some weird reason the volume of the pedal is much lower than it is supposed to be.

[Solidhex]

Yo

  I've built two FTM's using the General Guitar Gadgets layout. Both don't sound as gainy or fuzzy as they should. I've tried lots of transistors since I built both of them with sockets. Voltages all look good. I shelved them a while ago. I've learned a lot since I built them so I've been meaning to take a good look at them and see what I did wrong back then. We might have similar build problems since from what I've heard FTM's are supposed to be pretty gnarly.

--Brad

[DBDbadreligion]

but my problem is, I have it back to the original layout since i didn't like the mod.  but i don't know what went wrong, but my volume is lower than it was before.

[head_spaz]

  Changing D3/D4 ( http://www.generalguitargadgets.com/diagrams/ftmsc.gif ) from germanium to silicon type
  would result in a much hotter output and a bit less sizzle to the tone. 
  Do try and maintain the use of Ge types for D1/D2, though.
  Blah, blah, blah...

  ok i tried exchanging D1 and D2 for the 1N4001's, i didn't like it at all.  So i changed it back to the germaniums. 
  now for some weird reason the volume of the pedal is much lower than it is supposed to be.
 

  Maybe you were absent that day in third grade when your class learned that reading is supposed to   enlighten,
  via this thing called "comprehension."  Reading was never meant to be an exercise for just mouthing the words.
  Now, young man, give me that knife!

[DBDbadreligion]

  Changing D3/D4 ( http://www.generalguitargadgets.com/diagrams/ftmsc.gif ) from germanium to silicon type
  would result in a much hotter output and a bit less sizzle to the tone. 
  Do try and maintain the use of Ge types for D1/D2, though.
  Blah, blah, blah...

  ok i tried exchanging D1 and D2 for the 1N4001's, i didn't like it at all.  So i changed it back to the germaniums. 
  now for some weird reason the volume of the pedal is much lower than it is supposed to be.
 

  Maybe you were absent that day in third grade when your class learned that reading is supposed to   enlighten,
  via this thing called "comprehension."  Reading was never meant to be an exercise for just mouthing the words.
  Now, young man, give me that knife!

Man I am dumb, I got confused and thought I read D1 and D2 for some reason.  so what do I need to do?  Get new germanium diodes?

[DBDbadreligion]

bump

[axg20202]

Maybe. Diodes are quite heat sensitive. Maybe you have damaged them in the process of soldering, desoldering, resoldering??

[DBDbadreligion]

Maybe. Diodes are quite heat sensitive. Maybe you have damaged them in the process of soldering, desoldering, resoldering??

ok is there a way to tell if it's damaged?  it doesn't look burnt or anything.

[axg20202]

http://www.noahtec.com/testing-diode.htm

...armed with this info, you too could become a 'Porfessional'