My Tone Bender Voltage Correct?

[fuzzymuff]

Just built the pump'd tonebender, sounds great, but I have to turn the level control all the way to max to get unity with the bypassed signal.  At mid level, the volume is low.  The pump'd fuzz face was much louder and unity was about 1:00 of the volume control.

I was a bit bummed out that the charge pump I ordered with it was DOA, but I got a hold of a Max1044 charge pump...in my junk bin.

Here are my voltages.

Power source: 9.40v

Q1:

E=0.00

B=-0.05

C= -9.15

Q2:

E=0.00

B= -0.10

C= -0.37

Q3:

E= -0.26

B= -0.37

C= -4.44



Charge Pump:

1= 9.40

2= 4.01

3=0.00

4= -4.56

5= -9.36

6= 5.40

7=7.63

8= 9.40

[Pyr0]

Which layout did you use, and did it include a Q3 bias trimmer ?
The voltages kind of look ok except for Q3, adjust the bias for a higher collector voltage, I personally like it when it's around 8.5v.
A higher collector voltage on Q3 will give you more volume and a hell of a lot more sustain.
The 4.5v setting that people talk about might be true for a fuzz face, but most of the original tonebenders had a much higher Q3 collector voltage.
I find it best to adjust the bias trimmer by ear.

[fuzzymuff]

I used the layout from guitarPCB.  Yes, it has a 20K trimmer.  Here are some pics.

[Pyr0]

Well try adjusting the trimmer for a higher Q3 voltage, set it around 8v and see what it sounds like, you might like it.

[pinkjimiphoton]

Which layout did you use, and did it include a Q3 bias trimmer ?
The voltages kind of look ok except for Q3, adjust the bias for a higher collector voltage, I personally like it when it's around 8.5v.
A higher collector voltage on Q3 will give you more volume and a hell of a lot more sustain.
The 4.5v setting that people talk about might be true for a fuzz face, but most of the original tonebenders had a much higher Q3 collector voltage.
I find it best to adjust the bias trimmer by ear.

+1

[Arcane Analog]

The trimmer being on Q3 is unfortunate.

[fuzzymuff]

Which layout did you use, and did it include a Q3 bias trimmer ?
The voltages kind of look ok except for Q3, adjust the bias for a higher collector voltage, I personally like it when it's around 8.5v.
A higher collector voltage on Q3 will give you more volume and a hell of a lot more sustain.
The 4.5v setting that people talk about might be true for a fuzz face, but most of the original tonebenders had a much higher Q3 collector voltage.
I find it best to adjust the bias trimmer by ear.

+1

Hey Jimi, did you set your guitarpcb tonebender at 8.5v as well?  Your youtube demo of it sounded fantastic.  What was your unity level at?

[fuzzymuff]

Well try adjusting the trimmer for a higher Q3 voltage, set it around 8v and see what it sounds like, you might like it.

Will do, stay tune.

[pinkjimiphoton]

hey fuzzy,
i rarely ever set any bias on fuzzes to any arbitrary voltage.
i just tweak 'em til:
A: i can get it to be controllable from my guitar
B: it sounds good to ME.

so no idea!!

i'll try and dig it out, and see what the voltage is set at, and report back.

[Arcane Analog]

I think you would have more success pulling that Q3 trimmer and putting the stock 8K2 back in or set it for 8K2. Then bias Q2 with a temporary pot until you hit the tone you want. You will have way more control over the sound and it is easier to hit the sweet spots for Q2 and Q3 voltages.

[fuzzymuff]

I think you would have more success pulling that Q3 trimmer and putting the stock 8K2 back in or set it for 8K2. Then bias Q2 with a temporary pot until you hit the tone you want. You will have way more control over the sound and it is easier to hit the sweet spots for Q2 and Q3 voltages.

I hear ya...so remove the 20K trimmer and put back the 8.2K?  So how would I hook up the temp pot to bias the Q3 collector?

[fuzzymuff]

Which layout did you use, and did it include a Q3 bias trimmer ?
The voltages kind of look ok except for Q3, adjust the bias for a higher collector voltage, I personally like it when it's around 8.5v.
A higher collector voltage on Q3 will give you more volume and a hell of a lot more sustain.
The 4.5v setting that people talk about might be true for a fuzz face, but most of the original tonebenders had a much higher Q3 collector voltage.
I find it best to adjust the bias trimmer by ear.

+1

Cool, thank man.

[fuzzymuff]

Well, I just juiced up the Q3 collector all the way up to 8.00v and.........................................the unity level is mid way, its much louder now.  Seems to have much more headroom and it does seem to have much more singing sustain.  Jeeze, so all this talke about setting the bias to 4.5 does not hold true for every tonebender build.  I guess it depends on the Ge trannies, leakage and hfe?  The set of Ge trannies that I ordered with this bender kit had hfe ratings at 69, 79, and 108....  and three have 0 ma leakage from what it was written on the packaging. 

[Arcane Analog]

The 4.5V is a Fuzz Face or variant recommendation and even then alot of folks do not adhere to that.

For the Q2 collector, just use a base resistor of 1K in series with a 100K pot. Pick your sweet spot and then measure the pot and add the 1K and you have your value.

Not having any leakage in Q1 is strange to send out as a kit. Q2 and Q3 are not as picky but I always like to have some leakage in Q1.

[fuzzymuff]

Thanks Arcane Analog.  I'll try that out.

[Pyr0]

The gains on those trannies look good, but just for laughs and giggles, if you have the transistors in sockets, try swapping Q2 and Q3 and see if there's any difference in sound.

[fuzzymuff]

The gains on those trannies look good, but just for laughs and giggles, if you have the transistors in sockets, try swapping Q2 and Q3 and see if there's any difference in sound.

Hmmmm...now you are making wonder if I actually soldered these transistors in the proper order.......hmmmmmmmmm

[Electric Warrior]

Not having any leakage in Q1 is strange to send out as a kit. Q2 and Q3 are not as picky but I always like to have some leakage in Q1.

Not strange at all. The Impex transistors Sola Sound was using sometimes have hardly any leakage at all. They set those up with hfes of Q1 and 2 in the 20s or 30s and Q3 in the 2 or 300s. Not all that easy to set it up. I've tried several transistor types with no success. It tends to oscillate and I didn't get the sustain it should have.

Hmmmm...now you are making wonder if I actually soldered these transistors in the proper order.......hmmmmmmmmm

I tend to like them better with Q2 having a higher hfe than Q3 I think. But then again I just pick them by ear and rarely do measurements..
A "good" set of trannies should deliver plenty of volume boost.

[fuzzymuff]

Not having any leakage in Q1 is strange to send out as a kit. Q2 and Q3 are not as picky but I always like to have some leakage in Q1.

Not strange at all. The Impex transistors Sola Sound was using sometimes have hardly any leakage at all. They set those up with hfes of Q1 and 2 in the 20s or 30s and Q3 in the 2 or 300s. Not all that easy to set it up. I've tried several transistor types with no success. It tends to oscillate and I didn't get the sustain it should have.

Hmmmm...now you are making wonder if I actually soldered these transistors in the proper order.......hmmmmmmmmm

I tend to like them better with Q2 having a higher hfe than Q3 I think. But then again I just pick them by ear and rarely do measurements..
A "good" set of trannies should deliver plenty of volume boost.

You know, I've built other tonebenders and the generaguitargadget that I've built had a set of OC75s.  It had no trimpots and just used the resistor values that smallbear sent with the transistor set and it is LOUD, unity was about 9:00 and it cleaned up like and overdrive with the guitar's volume control.  When turned up, its full singing, sweet fuzz sustain.  

[Electric Warrior]

Can't quite make everything out, but is this based on the OC81D schematic? 100k at Q1's base and Q2's collector? And what voltages do you get with the alternate resistor values?