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Krell KAV 300i Problem

Hi, everyone,

My beautiful Krell KAV300i has started to show some issue recently that I hope somebody here can address the problem. Well, I can explain the problem as follows;

1- Amp is on, nothing connected to the input jacks, when I get closer my hands or touch one of the input RCA jacks a very high, annoying hum starts,

2- Amp is on and I play and listen to something thru one of the single ended inputs without having a problem. But when I switch to an empty input channel annoying hum starts again.

This probably happens to be a grounding problem and just have occurred very recently. Something has failed inside the amp but what would it be? I have been using another system using the same AC outlet having no problem at all. I also tried this amp in another room but the problem was still there.

I’d like to have comments on this.
Thanks.
hmavunduk

Showing 2 responses by almarg

almarg's avatar
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almarg
9,670 posts
 
That doesn’t sound to me like something that is necessarily abnormal, even if for some reason it wasn’t happening previously. Susceptibility to that kind of effect is probably contributed to by the very high 210K input impedance of the integrated amp.

What would most likely eliminate the issue is to simply put shorting plugs on each of the unused RCA inputs. Googling "RCA shorting plugs" will probably turn up some inexpensive choices (as well as some unnecessarily expensive ones), or you could make your own by shorting out the internal contacts on some ordinary RCA plugs.

Or, if the problem is in fact being caused by some hardware issue that is developing in the amp, without having any knowledge of the specific design I’m guessing that it might be related to a line filter capacitor on the amp’s AC input that is becoming leaky.

Good luck. Regards,
-- Al

almarg's avatar
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almarg
9,670 posts
 
No, that doesn't sound normal, if you were measuring between the center pin and the ground sleeve of each of the two RCA connectors, or between the center pin of one connector and the center pin of the other connector.

On the other hand, if you were measuring between the ground sleeves of the two connectors it would be perfectly normal.

Regards,
-- Al
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