Switching from Tonebender MKII to Fuzz Face ?

[petemoore]

  I understand it as two things get simul-switched.
   bypassing the 1k resistor to ground on Q1 emitter to bump gain up at that stage.
  Bypassing the 100k feedback resistor with a 10k, reduces gain by increasing -feedback.
  ..and that'd make elegant sense I think, unless I'm reading it wrong, you'd need DpSt or DPDT to do it.
 

[frankclarke]

Here is what I meant (modified from from fuzzcentral for educational purposes):

Hi Pete,
Yes, that's what I meant. DPDT. One mode is a smooth Fuzz Face with a mild Q1 boost in front, the other is a weak sputtery Fuzz Face getting hammered by Q1. They sound very different. You lift the Q1 emitter from ground, and put a 1k from emitter to ground to reduce Q1 gain. This is good if you think the TBII has too much gain, and this is one position of the switch.

This is if your TBII has ridiculous gain and you would prefer more of a Zeppelin vibe.

[frankclarke]

Holy Expletives Batman, Jeff shows you his pedals, TBIII:
http://www.youtube.com/watch?v=-p05vOgGNSo

[Krinor]

Thanks for the schematic/layout. Very nice. I'll have to fit my Tonebender in a larger box now. 

[tcobretti]

Frank, that is very cool. Thanks for the ideas!

[frankclarke]

Build Your Own Clone DPDT bypass for Q1
http://www.bigtonemusic.com/TBmods.html

[petemoore]

  thanks Frank, I'll have to try this one out !

[niggez]

I just installed the http://www.bigtonemusic.com/TBmods.html tbmod to switch from tb2 to fuzzfaze! Its amazing, this is what actually makes me box up this pedal!!
But there is one issue still left for me: When switching from fuzz face to tonebender, the gain increase is too great. Im going to install another stomp switch to switch between the 2 options, but right now i still have to lower the gain after switching, or i am just too loud.
So how can i lower the gain a bit - only of the tonebender part. I dont want to lose any more gain overall, because that would make the fuzz face too soft. So it would probably have to be around the q1 stage of the circuit, since this is the one only being used by the tonebender?

[niggez]

and i already have the emitter resistor on q1 installed

[tcobretti]

What you could do is leave everything the way it is, but use a 3PDT switch to switch between TB and FF.  Wire as described before, but on the extra row of lugs, you run the output of the circuit to the center, then run each outside lug to a 100kA Volume pot.  Run the wiper of each pot to the main switch and run Lug to ground.  This give you independent volume settings for each fuzz.

Here's a quick schem:





It's early and I just got up, so make sure this works before you drill holes or anything.  I am concerned that it may pop when switched.  You may want to run to the switch before the output cap, then put a cap on each line before the pot.  I think this may help nullify the pop a bit, if it is there.

EDIT: I just realized that you didn't build Frank's pedal, so much of the mods above will not refer to your pedal.  However, the stuff I put in there should still work with your pedal.

[niggez]

Would it be possible to control the gain of the tonebender part by adding a bias pot to q1?
The tonepad layout for the tonebender uses a 20k trimpot to set the q3 voltage around 4.5, could i do something similar to q1?
Or, maybe increase the value of the 1k resistor at emitter of q1? Ill try out some other values there.

[niggez]

I now have a 2.2k resistor at the emitter of Q1 and it seems to me like its gotten more usable!
Something weird i noticed...my q3 voltage is around 7.4 - maybe thats why my gain is a bit extreme? And Q2 voltage much lower than the original. Strange.

[frankclarke]

You can bypass the Q1 emitter resistor with a 5uF cap just like Q3 if you want an extra gain control. The biasing does affect the sound a lot, but sometimes a "wrong" bias setting sounds "right" .

[niggez]

what value would i use for that gain control?

[frankclarke]

If you had a 2k pot you could replace the 2.2k resistor with that.

[niggez]

i have a 4k7 trimpot installed to control the gain of the tonebender stage.
Next Problem: Im trying to figure out a way to increase the gain of the fuzz circuit (increasing gain of Q2). It only runs at -0.3 V.

[niggez]

Done!
I can definately recommend this mod to get more flexibility in your tonebender mk2!
I now have 3 trimpots at Q1, Q2, and at Q3. The Q1 Only affects the Tonebender Circuit, because when switching to fuzz face, Q1 is not included. My voltages are way off from the recommended standards, but im pleased with the sound. (Q2 is 0.3V, Q3 is 2.7V)
The tonebender stage is not only fuzzier, but also louder than the fuzz face stage.

[niggez]

But i just discoverd a major flaw: I cant turn the volume up more than a few milimeters. If i turn the volume pot up all the way, my amp reaches maximum volume on its lowest setting!! what could be the issue here??? HELP!

[niggez]

Ok so now i had the idea to add a passive tonestack. I decided to go for a single knob tonestack, its similar to the big muff with slightly different values. I cant test it right now, because everyones asleep, but im hoping this will A) cut down the output volume a bit and B) give me some more finetuning options for the final sound.

[vendettav]

sorry to jump into the conversation but is there any NPN negative ground version??? I guess i could flip the caps and battery but if there's a legit schematic already...