Bizarre humming problem with PSW1200
soiset
Posts: 724
I have a psw1200 with which I have only listened to stereo sound thus far, using the speaker level inputs. A buddy has given me a Kenwood vr707 that I might enjoy 5.1 HT. I bought an $80 Monster sub cable so that I could use the preamp sub out on my new receiver. Changing nothing else, I disconnected the speaker level 16ga wires from the sub, and put the rca plug into one of the sub's two LFE inputs (not using a splitter). The sub began to hum quite audibly at what I assume is 60hz. The kicker here is that I hadn't even plugged the other end of this "directional" cable into the receiver. When I did that the volume of the hum doubled.
I called Crutchfield, from whom I had bought the cable and the tech fellow seemed not to be able to get away from the 'ground loop hum" idea, even though I kept telling him that nothing else was different than before, I've never had any hum previously, and that the hum was quite loud with only the sub end of the cable connected. He suggested that I just go back to the speaker level inputs.
It is almost as though the rca cable is acting as an antenna (I plugged in a cheaper cable and got the same result), but I thought that a high quality "shielded" cable would not transmit low level emi.
Any suggestions?
I called Crutchfield, from whom I had bought the cable and the tech fellow seemed not to be able to get away from the 'ground loop hum" idea, even though I kept telling him that nothing else was different than before, I've never had any hum previously, and that the hum was quite loud with only the sub end of the cable connected. He suggested that I just go back to the speaker level inputs.
It is almost as though the rca cable is acting as an antenna (I plugged in a cheaper cable and got the same result), but I thought that a high quality "shielded" cable would not transmit low level emi.
Any suggestions?
Post edited by soiset on
Comments
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Well, maybe I've answered my own question. I got home from work and tried plugging the rca cable into the red lfe input. Once the plug was entirely inserted, the rather loud humming disappeared. So I tried again on the white input, but no luck: the humming was still there. But, when I push the plug laterally while fully inserted, the noise vanished. My guess is that there is a bad ground at the left rca lfe input. When I plugged the cable into the center channel input, until it was completely seated, the noise was there. Anybody know for sure what is going on?
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Hello,
That sounds like an accurate diagnoses, a faulty ground on an RCA connection can definitely lead to loud humming. You may certainly remove the bass amplifier and send it to Polk Audio, 2550 Britannia Blvd., Suite A, San Diego, CA. 92154. Please include a short note giving us your name and address and a copy of your sales receipt.
Regards, Ken
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