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more Muff gain

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1/30/1998 3:49 PM

more Muff gain

Thanks to all who responded concerning mods to the big muff for bass guitar...these comments resulted in some nice improvements.

I still have another issue which I think was actually combined with the poor low frequency response of the circuit to cause the sputtering distortion effect. This issue is simply that I just don't feel that the input signal from my passive pickups is sufficient to drive this ciruit. I have gotten much better results running the signal through a preamp first. Even on the highest SUSTAIN setting, the input signal from the passive pickups only seems to distort for a short time, and requires a fairly heavy picking motion to get going.

So, how and where should I boost the signal gain...I was looking at the first stage. I must admit to not completely understanding how this emitter-amplifier works...there is very little in my Art of Electronics tome which discusses this circuit, in particular with what seems to be a feedback resistor connected between collector and base. Can someone help me out?

Thanks,

Matt

1/30/1998 10:36 PM
R.G.	That's a voltage-feedback stage, now passe since there are better biasing techniques. You could split the collector-base resistor in half and put a BFC from the midpoint to ground to short out all AC feedback. You could also just put in another clipper stage like the two that are there.

1/30/1998 10:38 PM
R.G.	Your note bothered me more after I replied. I've built probably a dozen muffs, and not a one wouldn't go into full distortion with a single coil Strat. You have a biasing problem somewhere in there that is keeping you out of the good distortion range.

1/31/1998 1:09 AM
matt	What is the nominal gain of the input voltage-feedback stage. I have measured someting around 10x.... Thanks for your ideas R.G....I think that I will start at the beginning, and verify my circuit's correctness from zero... -matt

2/7/1998 5:04 PM
Paradiddle7	I have had the similar problem. It was a couple of shorted components and a short in the switching system. I hope that helps. I have built about 20 of these Muff's and I haven't had anymore problems with minimal distortion levels. The Big Muff is a winner on my books! Thanks, Jeff

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