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Onkyo TX-2500, weird feedback noises

bambino

Member
I have an Onkyo Tx-2500 (mk1 version). Last summer it started making a bunch of loud crackling noises (like the sound you'd get if you dragged your fingernails across a live microphone) accompanied by a deep bass noise (sort of a pulsing womp womp womp womp... sound). This happens even when the audio knob is turned to zero and doesn't change regardless of whether I turn up the volume, but turning turning the base and treble knobs down two clicks makes it quieter. I tested it with various speakers, while also plugging it into outlets in different rooms. It was all the same.

I took it to an excellent local vintage hifi guy's shop. He tested it and said it was great; couldn't find any problems. He thought it might be feedback from my house's electrical system or other appliances.

I set it back up and it was fine. A month or so later it started doing the noise again. I found that if I unplugged the speaker wires from the backs of the speakers and just left the receiver on like that for a bit, the noise would go away. It went on like that for a few months, with the noise being less and less frequent. Then it was fine for several months with not noises at all.

The last few weeks, though, it's been making the noises nonstop. My old fix isn't working anymore either. I bought the Morley Hum Eliminator (I think it's made by the same people as the Ebtech HumX and is the same product with different branding), which I saw read about in some other AK posts.

It has the following warnings on the box:
1. Do not use on equipment with current draw of more than 6 amps (720 watts).
I'm assuming my Onkyo receiver is fine here...am I right?

2. Do not use on Power Amps, Powered Subs or projectors.
I'm guessing my receiver is not considered a power amp?

3. Use only one Hum Exterminator per piece of equipment.
Can I still plug my turntable into the "unswitched" outlet on the back of my receiver?

4. Do not use Hum Exterminator on power strips, multi-power supplies or Power Conditioners.
I assume this means not to plug a power strip into the hum exterminator (stereo>power strip>exterminator>wall socket)?
But is it ok to plug the exterminator into a power strip (stereo>exterminator>power strip>wall socket)?

I really hope the Hum Exterminator is compatible with my stereo, and that it solves the problem. I'm a little worried since the sounds my receiver is making don't sound like most people describe as a ground home. Anyway, a big thank you for any advice or ideas.
 
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2) Your receiver has a built in power amp so I probably would 't use it on that.

4) If you have to use the hum exterminator on anything, I would plug it in straight into the wall.

Your problem probably has nothing to do with what you have mentioned. In my experience, it sounds like a noisy pre driver transistor. Is it coming from one speaker or both? Both would indicate a power supply issue. One speaker would most likely be a noisy (bad) pre driver transistor.

If you're not familiar with basic troubleshooting technics then I would have somone else take a look at it. :beerchug:
 
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