Input pot and input impedance

[Bricolo]

Hi all


I'm building a gainclone (as some already know ) and I was wondering about it's input impedance


I've read several times that a 47k input impedance is the standard.


the gainclone's inpedance is 10k (R1)

with an input pot, it will be paralleled to the input pot

so when the pot is 100% up, impedance is 9.5k
and at 0%: 50k


is this a problem?
is there a way to have a volume pot AND a fixed input impedance?

[dhaen]

Hi Bricolo,

Originally posted by Bricolo

I've read several times that a 47k input impedance is the standard.

Fairly standard..

Originally posted by Bricolo

the gainclone's inpedance is 10k (R1)
with an input pot, it will be paralleled to the input pot
so when the pot is 100% up, impedance is 9.5kand at 0%: 50k
is this a problem?

Depends on the source impedance. The lower it is, the less the problem

Originally posted by Bricolo

is there a way to have a volume pot AND a fixed input impedance?

Not with a volume pot. You would need a constant impedance (switched) attenuator.

As long as the source impedance is in the order if 1K (most CD players), I don't see a big problem with the volume control.

Cheers,