Tonebender and guitar volume problems

[mordechai]

Let me bump this topic (which I raised earlier but which slipped through the cracks...)

I just finished a TB Mk 2 build and it sounds fine when the guitar is at full volume, but the second I roll down the guitar volume, the signal is totally lost.  I'd appreciate any suggestions to fix this.

[Joe Hart]

Are the transistors biased correctly?
-Joe Hart

[mordechai]

Yep...though I've now swapped out the original OC75s I was using for some 2n1309s, and it works much better.  Actually, the 2n1309s sound really great.

[Joe Hart]

Did you re-bias for the new transistors or did you just pop them in and it sounded better?
-Joe Hart

[mordechai]

I rebiased a bit -- I am using a 10K trim pot -- but they just plain sound better to my ears.  The tonal response is very similar to an earlier TB Mk 2 I built with OC75s, but with a little more clarity (less"mud").  I should also note that the 2n1309s have a bit higher gain than the typical 70/70/100 rating -- they are currently reading 90/100/135 for q1, q2 and q3, respectively.  Really impressed with the results, though I plan to tweak a bit further.  Right now, I am wondering what I migh be able to do to reduce noise a bit.  It's not terrible by any means but I'd liek to cut down on some of that hum when I'm not playing.

[Scruffie]

I rebiased a bit -- I am using a 10K trim pot -- but they just plain sound better to my ears.  The tonal response is very similar to an earlier TB Mk 2 I built with OC75s, but with a little more clarity (less"mud").  I should also note that the 2n1309s have a bit higher gain than the typical 70/70/100 rating -- they are currently reading 90/100/135 for q1, q2 and q3, respectively.  Really impressed with the results, though I plan to tweak a bit further.  Right now, I am wondering what I migh be able to do to reduce noise a bit.  It's not terrible by any means but I'd liek to cut down on some of that hum when I'm not playing.

Rearrange the transistors, your gains are fine, I dunno where that 70/70/100 comes from.

You want high leakage for the first transistor and high gain/low leakage for the second transistor in general, this sounds best and has the least noise but experiment, with 3 transistors you can have alot of combinations. This may help with the noise issues and also with the volume control problem.

Try using a 100k on Q2s Collector for bias too with the 10k on Q3 working as an overall control, you may find that helps matters.

[mordechai]

Actually, now I'm having a problem I can't figure out.  Earlier this morning, the circuit was saturating really well, but now, it's not saturating at all.  The signal is passing through when the switch is on, but I'm not getting any fuzz happening.

[Scruffie]

Actually, now I'm having a problem I can't figure out.  Earlier this morning, the circuit was saturating really well, but now, it's not saturating at all.  The signal is passing through when the switch is on, but I'm not getting any fuzz happening.

Was it colder or warmer by any substantial amount this morning?