Tubescreamer - Low Output

[stumper1]

I "used the search function" for a couple of hours and I'm still stuck.  I built a Tubescreamer from the Tonepad layout.  So far NO mods but I did use several sockets so I can try different things later.  All parts are per layout except:
.022uf input cap instead of .027uf
Used metal film caps for all non-polarized caps
47pf instead of 51pf accross clipping diodes
Output resistors are 100/10k per TS808
For the time being I only have a 100k A taper pot for the level control.  I understand that the taper will be funny but all the way up the signal is barely above unity gain.  Everything else seems to work fine and sound great except for the low output.  Voltages seem OK too(at least per Tonepad):
IC
1 - 4.47
2 - 4.64
3 - 4.55
4 - 0
5 - 4.65
6 - 4.7
7 - 4.62
8 - 9.2

Q1 E - 3.67 B - 4.02 C - 9.2
Q2 E - 3.65 B - 4.01 C - 9.2

I've tried both 3904's and 5089's and have the same output.  Could it just be the pot or have I missed something?

Any help is appreciated - Thanks!

[petemoore]

Id audio probe it, looking for volume changes [no increase] in the buffers from B to C [input to output of buffers].
 ALSO on the OA's look for volume increase between input and output [should be a volume increase on both OA's, if the gain knob is set high].
 Generally probing looking for volume decrease at any point except the tone section, as the signal path goes throughthe passives of the TC section, there Should be some volume drop from before/after the passives.

[Gus]

check your resistors in the feedback network at the first 1/2 of the opamp.  The one that goes from the - to ground via a cap and the one in the feedback path with the gain pot make sure you have the right values.

Does the tone section work?

The transistor are not a big deal in a TS they are EFs.  Your voltages look OK

[stumper1]

Thanks for the tips!!

I checked the values of the resistors in the feedback loop (as well as all the others) and they are correct.

I probed B and C on the buffers and they were the same but the output side - Q2 - is louder than the input side - Q1.  I also noticed that Q2 is louder than the output jack - does that mean my problem is between the buffer and the jack?

On the clipping side of the OA there is an increase between the in and the out.  On the otherside it is quite loud but no volume increase from in to out. (OA #1 pin 3/in pin/1 out?).

The tone control works but seems kind of subtle - not sure if that is normal or not.  The Tonepad layout shows a cap labled "CA" that is "empty" - is this correct?

Thanks again!!

[stumper1]

Found it!!!  The 100 resistor after the output was bad.  Now I can hear the tone control better too!!!


Thanks again for all the help!!

Deric