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Nasty hum in Adcom GFP-555 II preamplifier

vinylvirgin

vinylvirgin

Member
A while back, I got an Adcom GFP-555 II preamplifier. On powering it up initially, I found that signals monitored through the unit's headphone jack sounded just fine. The sound coming from the unit's main output was another matter. It had a nasty 60-cycle hum.

Has anyone here who has owned this product encountered the same issue that I have? If so, how did you eventually solve it?
 
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vinylvirgin said:
A while back, I got an Adcom GFP-555 II preamplifier. On powering it up initially, I found that signals monitored through the unit's headphone jack sounded just fine. The sound coming from the unit's main output was another matter. It had a nasty 60-cycle hum.

Has anyone here who has owned this product encountered the same issue that I have? If so, how did you eventually solve it?
Click to expand...
Looks like the headphone output and main output have different power supplies. Check the regulated +/-18VDC supplies.
 
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