Lowrider, yes I live in a house with a service panel.
The hum is gone!!!!!!! Hooray...
I connected it to a different receptacle of my power conditioner, and swaped the pre-amp and the RCA cable, it's black quite background now - now I can enjoy my main system I put so much time / energy/ and money into it...
Thank you so much to all those who helped out here!
You guys are swell...
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The cheater-plug will help troubleshoot the hum. If the hum stops when it’s plugged in then there’s a ground-loop. To review, you disconnected all audio cables from the amp and you plugged the amp into different receptacles. It’s possible they may be on the same circuit. Last thing to try, plug the amp into the refrigerator or air conditioner receptacle. They are possibly on dedicated lines, different circuits than your audio system. Do you live in a house with your own service panel (circuit box)? |
Test the amp with a cheater plug, an adapter which removes the ground. https://www.target.com/p/general-electric-2pk-grounding-adapter-polarized/-/A-14442316?ref=tgt_adv_X... If it removes the hum then you have a ground fault somewhere. |
mijostyn, excuse my extreme ignorance on Hifi, but how do I put a ground cheater on the amp's power cord? |
If the hum is physically coming from the amp, specifically from the power supply transformer, that is DC offset hum. This is eliminated either with something like a Humbuster power strip, or by trial and error to find what is plugged in or wired that is causing the offset. If the hum is heard to be coming out of the speakers then this is ground loop hum. So as usual we start with precisely identifying exactly what it is we are talking about. |
could be a number of things (ground loop, bad caps or power supply, etc. etc.). however, i've often found the culprit to be a slightly loose transformer, which can be fixed simply by screwing it down tighter. make sure you disconnect the power from the amp for a couple of days before you screw around with it |