Power Amplifier crackling and humming - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 2 Old 07-17-2019, 06:43 PM - Thread Starter
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Unhappy Power Amplifier crackling and humming


Ever since I switched to the Sumo Andromeda II power amplifier 2 years ago, I have had a case of crackling and humming coming out of the speakers.
I have switched pre amps, speakers, speaker wire, cables, sources, surge bars, power conditioners and also disconnected everything but the hum appears even when doing so.
I bought an entry level power conditioner, same issue.
I brought and paid a service center to fix it. They brought me in in the shop and showed me that the oscilloscope wasn't picking up anything.
I brought the power amplifier to the electronic store I work at and no buzz appeared.
I then made the connection that it seems like there is an issue with the electricity of my old building (70s) and the old Sumo (80s).
I tried unplugging every single device in my apartment and only having the sumo on.
I bought an isolation transformer, did not fix. I bought a cheater plug, did not fix.
I also opened up the Sumo and sprayed it with some audio cleaning solution.

Thing is I tried all those things throughout the 2 years because every 'fix' is misleading, the hum will disappear for a few days and will come back randomly.
It seems to depend on the time of the day, the time of the month and whatnot.
The hum is sometimes extremely loud and sometimes faint. Crackling also appears with the hum sometimes. The hum on the right channel is louder than the left although left can also be quite loud.

I love the sound of the Sumo Andromeda II. I have it paired with a matching Sumo Athena pre amp and a pair of LS50. I also run some rather high end cables like Klipsch reference speaker wire and some audioquest cables.

Almost every day, I have spent a couple hours researching but now I am driving my wife crazy so I am hoping somebody might be able to help me out.

Timothy Le Masson is offline  
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post #2 of 2 Old 07-18-2019, 06:12 AM
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Maybe a bad solder joint in the amp or something. Gently wiggle all the connections on the amp to see if that changes anything. Even if not you could take it apart and use a magnifying glass or jeweler's loupe to inspect ALL of the solder joints.

If you hook up the amp with no input (or, better, if you short the input), but with the speakers hooked up, do you get noise?
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