big muff, little volume

[matt.w]

hey there,

i've just finished my first effect - a big muff (http://www.generalguitargadgets.com/v2/diagrams/bmpsc.gif) which works well but produces pretty low volume produced when the effect is on...
I'm getting the following voltages out of Q4: 3.92V @ collector, 1.57V @ base and 1.07V @ emitter.  The latter two differ from the sample voltages (2.5V and 1.8V respectively) provided with the build instructions.

any ideas?
cheers,
matt

[smoguzbenjamin]

Doing the math I'd say around 1.8v at base is ok, look at the bias resistors R21 & R22. rounding them off you have a total resistance of 500k. 9v of energy being dissipated through that, of which 400k drops the voltage initially. So 80% of the voltage is dissipated in the first resistor leaving 9v * 0.2 = 1.8v


Not sure about the others though... This is why I like trimpots!