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previous: R.G. Updated Wah Technology article -- 8/26/1999 12:08 AM

Wha-Volume on the Boomerang and Mr. Cry Baby

8/27/1999 11:25 AM
GFR	Wha-Volume on the Boomerang and Mr. Cry Baby Now it's clear how the wha/volume switching works. You lift the grounded end of the 4.7u cap and you've got AC feedback - now the first transistor is an inverting amplifier with the base being the low impedance point for summing currents. Now use a big capacitor in series with an appropriate mixing resistor from the emitter of Q2 to have variable full-range feedback - instead of a variable capacitor it's now a variable resistor. The pot is now a gain control!

8/27/1999 11:25 AM

GFR

Wha-Volume on the Boomerang and Mr. Cry Baby

Now it's clear how the wha/volume switching works. You lift the grounded end of the 4.7u cap and you've got AC feedback - now the first transistor is an inverting amplifier with the base being the low impedance point for summing currents. Now use a big capacitor in series with an appropriate mixing resistor from the emitter of Q2 to have variable full-range feedback - instead of a variable capacitor it's now a variable resistor. The pot is now a gain control!

Replies:

R.G. Yeah, pretty slick. The Boomerang d... -- 8/27/1999 2:29 PM