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Bricolo 18th March 2003 07:08 PM

Input pot and input impedance
 
Hi all


I'm building a gainclone (as some already know :D) 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 19th March 2003 01:59 PM

Re: Input pot and input impedance
 
Hi Bricolo,
Quote:

Originally posted by Bricolo

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

Fairly standard..
Quote:

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
Quote:

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,


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