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Loud background noise: cables picking up RF?

I have a significant background noise problem in my system. At normal listening levels, I am getting static that is audible from 15 feet away, and also a whistling sound coming through the speakers from time to time. I suspect that it is possible that my system is picking up some RF from the air, or that it is coming up through the electrical system. FWIW, around 2 miles from my house and 500 feet up, there is a broadcast array: 5 full-power FM towers, 2 NTSC full-powers, and some lower-power FM stations. A potential issue?

If this is the case, should I be going to a shielded-type IC? I get the noise as soon as my preamp and amp are engaged, whether or not I have a source hooked up. Can I buy a cheap AV-style IC from Best Buy and and see if the cables are the problem, or are those low-end IC's they sell really shielded? Are the power cords also a likely culprit? FWIW, I have

Any other ideas? I recently had my entire system checked up by the manufacturers, so all of the equipment is in good working order, but I can't seem to remove that background noise. Both my preamp and CDP are tubed, not sure if that is bad or not.
dawgcatching

Showing 3 responses by dawgcatching

dawgcatching OP
139 posts
 
Thanks for the advice. Describing the sound: I get a whistling sound when my CDP is engaged and I am on that input (probably some sort of DC leaking there) and a general hum when I turn the amp and preamp on together (not present when the amp only is activated). I am also getting a static background noise when I have my preamp hooked up (a Herron) but the preamp was just back at the factory and checked out fine. Perhaps it has something to do with the preamp tubes picking up something out of the air, although my backup preamp (EE Minimax, also tubed) isn't picking it up, and is much quieter.

The static is pretty constant: the whistling noise and hum comes and goes, although I usually hear the Whistling around 15 minutes into listening. It tends to diminish over time, but can still be heard at high volumes.

I should have posted this earlier: I am headed out on vacation on Monday, so I won't get time to start troubleshooting the system until I get back.
dawgcatching OP
139 posts
 
As far as the frequency scope goes, I will pick one up when I get back. The background static noise gets more audible as the volume increases: if I want to run my volume control to high listening levels (but not deafening) I can hear the static in the other room. The Hum level, however, is constant no matter the volume.
dawgcatching OP
139 posts
 
Is there any way I can check for a ground loop w/o buying equipment? If it comes to that, so be it, but is there any way I can test it? I tried grounding my preamp, with no change. Unfortunately, I cannot run a balanced system, as my preamp and CDP (a modified Sony 9000es) won't allow, but if necessary, I can always look at getting balanced components in the future. And, as an answer to another question, I am using the same outlet for my components. Should I be using 2 outlets, or 2 circuits? Perhaps I should think about installing a dedicated audio circuit? There isn't anything else on my current circuit, save for a lightbulb, that I am aware of.

Again, thanks for the help. I will try the shielded IC's and get back to you with the results when I am back from vacation.
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