2. amps-preamps
  3. 1119721790

ADCOM GFA 555-II distortion alert?

After running an hour or two, rt. "distortion alert" indicator lights on my 555-II. For the most part, this does not result in a readily audible difference, although I have gotten fuzz on the right channel. Local service center could find no problem; said it must be a problem elsewhere in my system. I've run it with two CDPs (NAD, Sony), two sets of speakers (DYI, Onix), and both stock/zip and Signal Cable interconnects/speaker wire. Only the ADCOM GTP-400 pre has been constant; could it be the pre, or is it more likely, as I think, the amp? Any thoughts much appreciated. May be time to replace, but it has been a good amp. THX! John
jdoris
5 responses Add your response
jdoris OP
972 posts
 
Wow, probably my first thread on the 'Gon! Seven years. Wish I had some advice, Lulu, I never figured it out, and moved on to Odyssey, and then to Pass.

The store that "serviced" it is out of business, as it should be.

Good luck,

John
lulu33
1 posts
 
I am experiencing the same problem on an old ADCOM 5200 attached to a Boston Woofer. I has to run for a 2-3 hours before the light comes on.
jdoris OP
972 posts
 
Thanks to Eldartford and Warnerwh. Have now replicated problem with amp disconected from system, so as you suspected, it is the amp itself. Simply being plugged in and turned on generates enough heat to trip the indicator. Placement is well-ventilated, so I doubt that's it. Will return to local techs, without much confidence. They must not have run it for very long! A trip to ADCOM, last I checked, was $140 + sh, more than the value of the piece warrants.

Thx again, John
warnerwh
539 posts
 
Be sure there's plenty of ventilation so it can't over heat.
If it's in the same place it's always been and you haven't changed anything then the tech guy is where to go.
eldartford
4,262 posts
 
It is in the power amp. The "distortion indicator" simply tells you that the output, adjusted for gain, does not match the input within some tolerance. The comparitor circuit or possibly the tolerance-setting device is probably temperature sensitive. IMHO the local guys ought to be able to figure it out.
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