Attenuator Impedance for Adcom GFA-535? - diyAudio
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Old 4th January 2013, 12:29 PM   #1
diyAudio Member
Join Date: Oct 2011
Default Attenuator Impedance for Adcom GFA-535?


I'd really appreciate a recommendation as to what impedance attenuator I should purchase for my newly acquired Adcom GFA-535--which has an input impedance of 100k Ohms.

I have a 20k ohm stereo potentiometer at the moment, and the sound sounds pretty veiled (with the 535) compared to the Behringer A-500 I had (which had an input impedance of around 22k ohms).

Would it benefit to use a 50k ohm or 75kohm potentiometer instead for this Adcom?
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Old 4th January 2013, 01:45 PM   #2
diyAudio Member
Join Date: Jun 2007
Your 20kOhm pot should be okay.

If you change, you would want a smaller value and not a larger value. Please note that the input Z on the Adcom and the inherent capacitance of the interconnect will form a RC low pass filter. A cheap, or very long interconnect may be your problem.

Do you access to a spectrum analyzer?
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Old 5th January 2013, 02:26 PM   #3
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Join Date: Oct 2011
Ok I think I might stick with this 20k potentiometer.

The amp actually sounds much better now after a few days burning in. It's really opened up! It sounds better than the Behringer A-500 now.

Have you all noticed an old solid state amp opening up after a few days of use?
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