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Re: Crackly preamp!

Subject: Re: Crackly preamp!
From: "Terry King" <>
Date: Sat, 16 Oct 2004 08:15:13 -0000

> > I've just invested in a small line powered preamp for my minidisc. 
> > The slightest movement at the jack plug is causing it to crackle. 

Walter, a more remote possibility to check is the presence of DC
offset or leakage on the signal lead.  If a capacitor in the preamp
output circuit is 'leaky' then a DC voltage will be present on the
output signal. Even a small discontinuity in a connector or movement
in a cable shield can create noise.  

Test this by measuring the DC voltage across the connector while
plugged in your normal configuration. It should be very small (less
than .01 volts) or unmeasureable, using a typical small digital
multimeter.

Try a temporary 'fix' by inserting a good .1 microfarad capacitor in
series with the signal. If the crackles are gone, you found the problem.

IF this is the problem!

Regards,  Terry King  ...On The Med in Carthage





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