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Old 18th March 2003, 07:08 PM   #1
Bricolo is offline Bricolo  France
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Default Input pot and input impedance

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?
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Old 19th March 2003, 01:59 PM   #2
dhaen is offline dhaen  Europe
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Default 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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