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Old 5th December 2008, 10:11 AM   #1
diyAudio Member
Join Date: Feb 2004
Location: manchester
Default Passive pre

Hi all

I have a very high quality Penny & Giles pot I acquired from a previous employer when it shut down, it was custom built for the speaker ouput control in a 400K mixer. I think the pot itself cost us 200 at the time from P&G, hand made laser trimmed etc as I recall. It has very accurate channel balance , thats why it was so expensive, 0.1db from what I remember.
Anwyay I fancy knocking up a passive pre using it. Its 10K log (hope its log anyway trying to find the cct it was used in..).
I would be connecting it between cd player and the input of my power amp which has a 33k imp.

Would this be ok? Or will I get hf trouble? I seem to remember last time I looked into passive pre it was advisable to use high impedance pot.

Advice welcome.

thanks folks ;-)
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Old 5th December 2008, 10:29 AM   #2
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Location: Cascais
Sounds fine. You should be able to confirm the log characteristic with your multimeter. Higher impedance pot is not preferable unless you have a very anaemic tube source.
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Old 5th December 2008, 10:44 AM   #3
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Join Date: Feb 2004
Location: manchester
great . thanks.
yes i will measure the pot. im at work now so its not here. i found it under the stairs other day and thought hmmm i should do something with that ! :-)
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Old 5th December 2008, 03:36 PM   #4
sreten is offline sreten  United Kingdom
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Join Date: Nov 2003
Location: Brighton UK

You get h.f. trouble with high impedance pots and long cables
from the pot to the power amplifier. 10K log should be fine for
1m to 2m of average capacitance cable, though of course you
can make it shorter.

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