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DIY Stompboxes => Building your own stompbox => Topic started by: $uperpuma on July 26, 2006, 12:21:01 PM

Title: Big Muff ALMOST there....
Post by: $uperpuma on July 26, 2006, 12:21:01 PM
hey guys I have just put together the Triangle Muff using the tonepad layout. I used 5088's and I love the way it sounds, until I turn my guitar all the way up, then the circuit attenuates to about 20% volume. roll it back to about "8" and its perfect... slightly confused on this one...

the only quirk I saw in building this one was slight ..on the layouts the 1m resistor on the input that is in red is not in the parts list but as it was on the layout, I included it. All other parts were correct according to the Triangle layout.

As always any help is MUCH appreciated.

thanks in advance,
-Nate
Title: Re: Big Muff ALMOST there....
Post by: GibsonGM on July 26, 2006, 02:31:25 PM
Sounds weird...I just built the BMP, and it's fine.  Nothing funny about your rig, right? No super-hot pups or crazy input levels for any reason?

Sounds like a misbiased transistor, or possibly an off value on the base blocking resistors (the 8.2K's).  Have you checked all your Q's for proper voltages?  You may be oversaturating your transistors into cutoff region because something is off.... Using 1N914 diodes, and are they in right?   I have a 4.7M resistor on my input to ground (your schem might be a little different), I believe this is to increase the input impedance...maybe increasing your 1M would help.
Hope that gives you a place to start, it's a great pedal once they're up & running!!

Title: Re: Big Muff ALMOST there....
Post by: $uperpuma on July 27, 2006, 04:07:33 PM
would Q voltages help the wizards help me on this one? I'll bump for now and try to edit in the voltages here in a few...
Title: Re: Big Muff ALMOST there....
Post by: jimbob on July 27, 2006, 07:36:08 PM
I just finished a triangle muff today. I havnt fired it up yet but this is the 3rd triangle so far in the last year so It will probbaly fire up.
Title: Re: Big Muff ALMOST there....
Post by: petemoore on July 27, 2006, 07:42:49 PM
would Q voltages help the wizards help me on this one? I'll bump for now and try to edit in the voltages here in a few...
  For BMP or something like it, I'd test the pin voltages of the 4 transistors...first...anyway.
  This gives /exacting info on how the 4 are biased, audio probe could be used but interpreting the results is has details and subcontexts to it...buffer  I/O should be 1/1 emitter sounding about like the base, and gain stages the output [collector] should be an amplified version of the input [base] on each of the Q's.