2. amps-preamps
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Hum in preamp when using HT bypass

I have a Sim Audio P5 preamp that has an HT bypass input. AT first I was using RCA interconnects from CD to preamp, preamp to amp and the HT bypass and had no problems. When I switched to balanced from CD to preamp and preamp to amp leaving the RCA connection for the HT bypass I am getting the hum. There is no balanced input for the HT bypass. When I choose my CD input I do not get the hum, only when I switch to the HT bypass input. Any suggestions?
kayoboy

Showing 3 responses by mitch2

mitch2
4,168 posts
 
Just to be clear, my recommendation for a "ground lift" was for the coax line from your cable or satellite source, and not an AC ground lift. I probably misused the terminology, since it is correctly described as "video isolation" by Hals_den. I agree with Bob_reynolds regarding grounding and safety.
mitch2
4,168 posts
 
If you have cable or satellite hooked to the television, you may need a ground lift or something similar to a Mondial Magic inline with the coax. I was told I didn't need that for satellite but turns out I did, and it worked. I would believe the cable/satellite/television is the culprit before doubting the Sim P5. Your local HT dealer should have some sort of an in-line ground lift in the $10-20 range - a good place to start. Good luck.
mitch2
4,168 posts
 
Yes IME it can. Any connection between units having cable or satellite connections can cause hum. Consider if your DVD player or processor are hooked to the television (which is hooked to cable or satellite) and also to the preamp via an rca cable which has ground and positive, they then share a ground connection. I am not an expert, but a ground lift cured the same problem in my set up, when I was attached to cable, and then later again after switching to satellite.
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