HELP: Squealing Polk Monitor Series 4 speakers driven by my Kenwood KR-6400

[silvermetal]

I recently picked up a Kenwood KR-6400 stereo receiver at an estate sale for cheap. It was in decent shape but I ended up deep cleaning it and refinishing the wood panels on it. I cleaned the pots and switches to eliminate the scratchy noise while turning them. I also replaced a couple burnt out bulbs so this receiver is lookin mean.

 

The receiver sounds great through my KLH 900b speakers but when I hook it up to my Polk Monitor Series 4 speakers there are random little squeals/squeaks/chirps at higher volume. It happens a lot more when the loudness button is pushed on (to my knowledge the loudness switch just spikes treble and bass levels?). I tried the phono and tape input to see if it was maybe an input problem but they both yielded the same squealing noise at higher volumes (by higher I don't mean speaker blowing levels. this receiver is only rated at 45 watts per channel). I then tried the Polk speakers with another receiver (that is working fine) paired with the same two inputs (phono and tape) I tried with the other receiver and there is no squealing.

 

So I have narrowed the noise down the Kenwood KR-6400 receiver and the Polk Monitor Series 4 speakers. I haven't ever heard a noise similar to this one through any speakers before. It is hard to describe but very distinct.

 

I was thinking that the receiver may need to be recapped since many of the capacitors installed in these vintage stereos were made to last 20 years. If that is the case than these are over due and could be leaking voltage. It could be that the smaller Polk speakers can't handle the voltage leaks from the capacitor as well as the larger KLH 900b speakers can? (not sure what voltage leaks even sound like but I am sure they vary from system to system)

 

If anyone has had this problem before please help me out. Any feedback is greatly appreciated.

 

Edit: Thought I would add a photo of the receiver (cell phone pick :/)

It looks too good. I just want to have it running perfectly

 

[ilikeguitars]

Congrats, i recently found a KR-7400 at a goodwill and it sounds great. Your problem does sound like it could be due to some bad capacitors. I'd suggest a recap and asking for help from the pros at audiokarma. 

[silvermetal]

Congrats, i recently found a KR-7400 at a goodwill and it sounds great. Your problem does sound like it could be due to some bad capacitors. I'd suggest a recap and asking for help from the pros at audiokarma. 

 

Okay cool that's what I thought. I would love to ask the folks on audiokarma but I don't have an account and registration is closed -__-

 

Anyone know if AK will be opening registration back up anytime soon?

 

I have a guy repairing some other audio equipment for me right now so I will probably just end up picking his brain.

 

Thanks for the feedback!