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From: jdhill@BBN.COM (Jack D. Hill)
Newsgroups: rec.audio.high-end
Subject: Re: Mods for Hafler 100 Power Amp
Message-ID: <8094@uwm.edu>
Date: 5 Dec 90 13:58:30 GMT
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Approved: tjk@csd4.csd.uwm.edu
Originator: tjk@csd4.csd.uwm.edu


In article <7696@uwm.edu> you write:
>
>About 8 years ago I built a Hafler DH100 power amp from the kit.  Throughout
>the years, it has suited my needs admirably.  'til now.  I am getting
>increasing hum and hiss in both channels, and I assume it's due to aging
>of important components and/or solder joints.  I would ideally like to
>replace the Hafler with a better unit, but at this point my budget
>(and wife ;-) won't allow it.
>
>I've heard of good modification kits for the DH100, and would like to hear
>from those who have experience, good or bad, with any of them.  Your help
>is greatly appreciated.

A year ago I purchased an upgrade kit for the DH100 direct from Hafler. It
costs under $20 and includes better op-amps and a few resistors and capacitors.
The upgrade involves replacing the socketed op-amps and soldering in the rest.
It turned out to be a nice upgrade. The biggest difference I heard was that the
high end wasn't nearly as grainy and harsh like it used to be. It sounds like
you might have problems in your power supply. Try repacing the diodes and
electrolytics.

Jack