Tri Muff sounds weak and bad

[Beros]

Hi

I just built a Triangle Muff from Markm's layout, and it's not really working correctly. The effect signal is lower than the clean guitar signal and it sounds rather weak and not really that fuzzy. I recycled the parts from another layout that I tried (Andrews) and maybe the components have been overheated?

Anyone have any clues on what might be wrong?

Does anyone know what voltages the trannies should have, and how I measure them? (where to put the meter... )

[petemoore]

I just built a Triangle Muff from Markm's layout, and it's not really working correctly.
  Probably sounds misbiased.
  The effect signal is lower than the clean guitar signal and it sounds rather weak and not really that fuzzy.
   I recycled the parts from another layout that I tried (Andrews) and maybe the components have been overheated?
  Maybe a transistor, I'd debug a little before swapping tho.

Anyone have any clues on what might be wrong?
  RG has most of the ones we've heard about in the debugging thread.
  Does anyone know what voltages the trannies should have, and how I measure them? (where to put the meter...
  I've seen voltages for BMP's around, something like E's real low' B is like 1.14v and C is around 1/2v...
  Get a working stage and use that to debug the others, IIRC one of the big sites with BMP types on it has actual transistor voltages.
  You should probably measure the votlages anyway, posting the readings here will help.
  Basically it sounds like it needs a regular debug, that'd be the stuff outlined in RG's debugging thread.

[Beros]

Here's the layout:



And the voltages:

Battery: 8.80

Q1
C: 4.52
B: 0.754
E: 0.186

Q2
C: 1.234
B: 0.676
E: 0.074

Q3
C: 3.859
B: 1.690
E: 1.111

Q4
C: 8.34
B: 1.447
E: 1.1021


Help please. 

[Toney]

Paraphrasing the inimitable R.G.

The base must be higher than the emitter by the forward voltage of one diode. Ie 0.5 or so volts.

So looks like Q4 is mis-biased.

I'd begin by carefully checking the resister values around the trannie and the wiring of the volume pot

[petemoore]

Q1
C: 4.52
B: 0.754
E: 0.18
  This ones good

Q2
C: 1.234
B: 0.676
E: 0.074
Collector seems low
Q3
C: 3.859
B: 1.690
E: 1.111
  Perty good
Q4
C: 8.34
B: 1.447
E: 1.1021
  Collector is output [?I can't read layout very well], I would look for what's causing the bias, inside the DC blocking caps on that stage.