Tone Bender voltages

[Outlaws]

Tonepad PCB

So I am getting into my Tone Bender a bit more. It's a Tonepad MKII Professional PCB.  I used matched germanium transistors from Small Bear.  He recommended I swap R3 to 30k and R4 to 118k.  Basic layout called for 47k and 100k.  I used a 100k trim for R3.
TI 2G30X transistors from Small Bear.

Now I understand that many places say Q3 C should be 4.5-5v, and then there are people saying it should be 8-8.5v.

Well I probed everything as I was using it at the 30k-47k area I had marked before soldering and it just didn't sound right. As I increase the resistance to Q2s Collector I see it ups Q3s Collector voltage. Well I maxed out my trim and it got Q3 C up to 7v.  This sounds much better imo. Everything is smoother. But I feel like I am not done.  I want to know what 8 or 8.5v is like lol.

I am using a Les Paul with Alnico II pros. I find every once in a while even with R3 at 100k I am getting a very rare sputter on the low end. It's not repeatable on a consistent basis.  But it has me wondering what I should be getting for voltages based on my transistors.

I also read the originals had a .01mf cap from effect in to ground. This circuit is seriously bright as is.  I might add that in too.

Q1: HFE 69, Leak 44
Q2: HFE 90, Leak 70
Q3: HFE 147, Leak 143

Battery 9.41v

With R3 100k trim at 100k

Q1
C 9.2v
B .05v
E 0v

Q2
C .29v
B .09v
E 0v

Q3
C 7.53v
B .29v
E .2v

---------

With R3 100k trim somewhere near 30k-47k

Q1
C 9.18v
B .053v
E 0v

Q2
C .574v
B .114v
E 0v

Q3
C 5.13v
B .576v
E .472v

----------

[Electric Warrior]

Interesting. The bias setup with the 100ks on Q1's base and Q2's collector is meant for lower leakage transistors, but it looks as if yours could still use more leakage. Your leakage readings seem to be all that low, though. I guess there are other specs that have an influence on how they bias.

I believe you may not be able to go much higher than 100k on Q2C, so try swapping Q2 and Q3 around. That will hopefully give you a lower voltage at Q2C and a higher at Q3C as they mostly depend on Q2's leakage and hfe.

The MKII came with and without the 0.01µF at the input. Most have it. It may work better behind a wah without the cap.

Here are voltage readings from my vintage unit for comparison:

Battery: 9.67V
Q1 C -9.02V B -0.03V E 0V
Q2 C -0.17V B -0.08V E 0V
Q3 C -8.44V B -0.17V E -0.11V

Note that Q1C is a little on the high side in this one.

[thermionix]

I was messing around breadboarding a Mk II a couple months ago.  Various transistors.  Every time I got the voltages where they were "supposed" to be, it would get a little gatey, "sputter" on the decay.  When I went for sound instead of voltages, I couldn't really get anything beyond a good Fuzz Face.  I ended up just scrapping it.

[Outlaws]

Well I managed to do a lot of testing. I didn't swap transistor positions yet, but I yanked out my 100k trim for Q2 and added a 100k resistor and a 10k trim for Q3.  (Couldn't fit both as trims on the Tonepad PCB) Got my 8.5 volts....and hated it.  It wasn't bad when rolling off the volume, but rather than being mooshy with guitar volume at full it was bordering on a fixed flanger type sizzle. It was gross.  So I figured I should now try a 47k and see how that reacts with the trim for Q3.  Well that was worse. I got sputtering on the bass note palm mutes.
So I am at 100k but fixed on Q2, and a 10k trim which I find 7.5-7.7v is my area I like a lot. Anything more I don't need. Regardless of vintage specs, I love the sound I am getting with this.  I don't understand how people want 4.5v at Q3, but then to each their own.  Now I am considering buying a DAM MKII just because I love the tone so much I want to hear what it's "supposed" to sound like so I can either figure out if there is more magic to unlock, or realize I did one better and actually tuned a TB to my own perfection.
Edit:
I added the .01 input cap.  All the difference in the world. This thing still cuts but I wouldn't label it as painfully bright anymore.