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One channel on power amp lost 4.5dB of volume?

Leviathan

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Aug 23, 2021
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So I am just starting to dip my toe into the audio world and I picked up my first power amp a few weeks ago. It was cheap because I don't have a lot of money to spend on this. It was a used AudioSource AMP300. I bought it from a guy that seemed very helpful, I didn't get the impression he was trying to sell me faulty electronics. I am using my RCA pre-outs from my Denon to go to the amp300.

Everything was going well until I turned it on yesterday and the left channel seemed quieter than usual. I changed inputs, changed out RCA cables from the Denon, flipped the inputs from the Denon, switched speakers, switched speaker wires, etc. Everything points to the loss of volume is from inside the power amp itself. I checked gain nobs and balance nobs twice, everything is set to even on the amp.

I had to increase the levels in the Denon up 4.5 dB on the left side to match the right side. I suppose I can continue like that, but what does this mean? Has anyone else experienced something like this before?

I suppose it could change back next week if it wanted to. Does it mean my amp is about to go? Will it take my speakers with it?!

Thanks for the help.
 

Sal1950

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My experience with a change like this has been a failure in the negative feedback circuit of the amp in that channel.
IME The amp "has gone" and needs repair. Further failure, speaker damage and alike is anybody's guess.
Get it fixed or replace it.
 
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Leviathan

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Oh, sorry, I didn't see these replies because they were so much later!

Have you flipped the bridge switch a few times ?

The bridge switch is a good idea.

And flip the Line input 1/2 switch a few times.

I definitely did that.

Unsurprisingly, a few days after my original post the left side went totally out. A few days later it was back on. A few days later it was off again.

I live in a high cost area, I am pretty sure it is not worth fixing. A shop will probably charge me more to diagnose and fix the amp than I paid for it.

Thank you for the help!
 

MakeMineVinyl

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When I've had this type of problem in the past, it was an RCA jack which had stubborn corrosion. Replacing the jack cured the problem in that instance, but your problem could easily be a bad amplifier channel.
 
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