Harman Kardon 495i

[bobbysl]

My receiver seems to be putting out less bass in the left channel. I've done enough experimenting with the speakers etc to determine the issue is the receiver. I am running it into a pair of Infinity RS5000's. I get lots of woofer bounce in one channel and minimal in the other, and when panning I can clearly here the less bass in one channel.

 

[kellys_eye]

Component tolerances in the tonal control circuit? Tolerances in the amplifier bypass components? Problems in the passive speaker filter components?

You really need to apply a known signal and monitor the output using the correct test equipment to 'prove' a fault or the best you will end up doing is changing the relevant parts on an ad hoc basis until you get the sound that pleases you.

 

[bobbysl]

I have had this system since new in the late 80's. It was put away last 10 years and I am now cleaning it up and getting it put back together. The less bass in one channel is a new thing.

 

[kellys_eye]

It's a known problem that (some) capacitors age badly - change value, change internal resistance - so finding such issues isn't unusual. Many restoration techniques involve 're-capping' equipment to guarantee both safety and operational specification but that can be overkill if the issue is simply 'one' component out of tolerance.

As I stated, you would need specialist test equipment to locate such an issue to specific component(s). One other method may be to add (or subtract) capacitance in the tone control circuitry until you get a matching response across both channels. Not ideal but far easier than a full re-cap procedure.

 

[Audioguru]

If the "woofer bounce" is on the channel that has less bass then it is probably a faulty series output capacitor that feeds the speaker. I assume "woofer bounce" is poor damping of the resonance.

 

[WHONOES]

Have to agree with Audioguru. Sounds like the output capacitor has dried out during storage. Simply replacing it may cure your problem. If you can, replace it with a bipolar electrolytic of the same value and voltage.
This advice assumes of course that the amplifier does not have a split rail power supply.

 

[bobbysl]

woofer bounce is in the one with more bass. The receiver is an HK495i from late 80's

 

[bobbysl]

Honestly the woofer bounce doesn't concern me too much, it's the other channel with less bass that does

 

[WHONOES]

My remarks in post #6 apply to the poor bass. When a capacitor dries out, it's effective value reduces which would cause the problem you are experiencing.