help improving a green Big Muff build

[alange5]

Hello all.  I just completed a green big muff build.  It works pretty well and when dialed into a good setting, it sounds great.  Problem is, the controls don't seem to have as much range as other muffs I've played.  I don't own an original green muff, but I do own an early black Sovtek (couple resistor swaps to bring it to green specs) and a Stomp Under Foot "Civil War".

Firstly, here's the layout I used:
http://diy-layout.com/9

I followed the off-board wiring diagram located on page 8 of this pdf:
http://diy-layout.com/9

And my issues are as follows:

-Unity volume happens a little after 12:00. This is consistent with the black muff, but not with the Civil War.  On my build, most of the volume boost happens past 3:00 on the volume knob.  By comparison, my build's maxed out volume is comparable with about 12:00 on the Civil War.  How can I coax out more volume?

-The sustain knob's range seems weak.  When A/B-ing with the black muff, my build sounds pretty wimpy for the first half turn of the sustain knob.  From there, sustain/fuzz gradually increases, but even maxed out, it's not nearly as fuzzy as the black one.  It sounds great as-is, but I'd like the option of pushing it over the top, especially in the last quarter-turn.

-The tone knob does something funny...  The tonal range is fine, but when turned fully counter-clockwise, it actually boosts the volume.  I A/B'd, and the black Sovtek actually does the same thing, though it's not as noticeable.  The volume levels out at about 9:00, then the tonal sweep sounds fine.

Most of these "problems" actually apply to both my build and my Sovtek, which makes me think these are inherent qualities of the circuit, however, I'd like to "modernize" it, like the Stomp Under Foot has done (more volume, more versatile sweep of the sustain control).  Any pointers?

Here are my transistor voltages:

Q1
C .08
B .63
E 6.75

Q2
E 6.33
B .64
C .1

Q3:
C .09
B .63
E 5.98

Q4
E 6.86
B 1.08
C .53



Any help would be much appreciated.  Thanks!

[LucifersTrip]

Did you do a little research for what the voltages should be before you built it? The C's are usually around 4.5-5V+, so either you measured incorrectly or you have multiple errors...


==========
edit:

My Green Russian:

[alange5]

sorry.  misread the transistor diagram.

Q1
C 6.75
B .63
E .08

Q2
C 6.33
B .64
E .1

Q3:
C 5.98
B .63
E .09

Q4
C 6.86
B 1.08
E .53


collector voltages seem high....

[armdnrdy]

This should help with any changes you want to make:

http://www.kitrae.net/music/big_muff_guts.html#Circuit

[LucifersTrip]

collector voltages seem high....

That can happen if you use very low hfe transistors (<100) or if you use wrong value resistor around the Q's...double-check

[alange5]

thanks for the help.  I double-checked resistor values and they are correct according to the layout...

Trying to wrap my head around this...  I'm trying to trace the voltage from where the 9v supply hits the board.  With a fresh battery installed, I read 9.45V.  R17 stands between the power supply and Q3's collector, correct? It's a 12K resistor, as per the layout I'm using, but I'm reading approx. 5.98V at the Collector. 

[LucifersTrip]

You should try to post a schematic in the post and tell us what transistors you used....

But yes, it looks like a 12K. The schematic that the link you posted above refers to is
http://www.generalguitargadgets.com/pdf/ggg_bmp_grus_sc.pdf

"Project description
The famous Green Russian Big Muff based on the schematic at General Guitar Gadgets."

...which would be R5. The other resistors around the transistor also affect the voltage, so check those
if you haven't.

The cool thing about a BM is that it's just 4 stages straight in a row. You can breadboard just that 1st
stage and experiment into oblivion without the rest of the circuit.

[alange5]

I used 2n5088 transistors.  Here are the specific ones I used: http://www.mammothelectronics.com/2N5088-FSC-NPN-General-Purpose-Amplifier-p/100-1000.htm

It just puzzles me that every collector on all 4 transistors is about 2V higher than the common range for big muff voltages.  I followed the layout and bill of materials with no changes or modifications.  Could it simply be blamed on the transistor specs?

I might try to swap in the transistors from my black sovtek muff and take new readings

[alange5]

Update:

I moved Q1 from my Sovtek over into my build, and the collector voltage is back where it should be. (about 4.2V).  So does that mean my transistors have gains that are too low? or too high? What components can I alter to get the voltage in check? The 12K collector resistors?

[LucifersTrip]

Update:

I moved Q1 from my Sovtek over into my build, and the collector voltage is back where it should be. (about 4.2V).  So does that mean my transistors have gains that are too low? or too high?

doubtful, if you used 5088's. Are you sure you have the pinouts correct? What transistors are in the black?

What components can I alter to get the voltage in check? The 12K collector resistors?

That would probably be the most common, but the resistors on B and E will also affect voltage.