How to build a circuit at unity gain? Where to put resistor.

Started by chumbox, July 03, 2013, 12:03:27 AM

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chumbox

Hey

Can someone explain to me how I could go about removing a volume knob and creating a pedal that's always at unity gain?  Is it just a matter of measuring the resistance on the pot and putting a matched resistor in the signal path before the output?

Thanks

mistahead

Most circuits around here seem use a voltage divider as a volume, as one of (or the last) stage before the output proper.

So 100K VR will have that 100K divided above and below the wiper - two resistors would be required to match, one from the signal out of the board (pre VR), one from the GND, join the ends and put to output.

chumbox


Bill Mountain

I'm not sure which kind of pedal you're using but you may want to make sure that any other gain or eq controls don't effect the output volume as well.

mistahead

I did make the assumption (as stated) that the OP was looking at a circuit around here (booster/preamp as a buffer I would guess) and most do the VR as a divider with the output hanging off the wiper as volume at the end...

Would the term "unity gain" be applicable still if we are looking at a circuit (lets go with a one NPN transistor booster) where within the circuit we push gain further than unity, apply filtering to frequencies, and then attenuate the output back down to create an output volume at unity?