Loud background noise: cables picking up RF?

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.

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.

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.

09-14-08: Musicnoise
No Jea48 you are incorrect - his speaker wire will not act as an antenna that causes transmitted RF to be heard through his speaker - that makes absolutely no sense - if that were the case he would be hearing RF all the time, with or without his amplifier on or connected. In every system on this planet the speaker wire is past the amplifier not before it.
Musicnoise

First lets keep the subject matter in perspective.

My response was in regards to living very close to a radio transmitting tower/s.

And yes in some instances there are people who actually hear the sound of radio station broadcasts coming through their speakers.

Had you taken the time to read any threads from the archives, here on Agon, you would of found a few threads on the subject. In probably most cases the RF signal will enter audio equipment through ics, sometimes through the AC power wiring. And yes sometimes through long speaker cables.

As for the speaker cable.... I do not believe I said that Dawgcatching static was caused from his speaker cables working as an antenna. My point was in some cases long speaker cables can act as an antenna if an audio system is in the close vicinity of a radio tower's antenna.

As I said in my previous post I do not believe Dawgcatching's problem is necessary caused by the communication towers.

I suggest you reread my last post.....

I also provided you a link to read.

Here is a quote from the link,
Quote:

AUDIO AMPLIFIERS
It's quite likely that the audio amplifier is performing RF detection. You need to place ferrites on the speaker cables as close to the audio output (right at the PC board if possible) with as many windings as possible. If it is audio detection, it won't matter at all how many ferrites you install on the power cord or cable TV or antenna cable although this will cut down on the amount of
RF getting into the TV via those conductors. Direct pick-up onto speaker wires causes most problems. Don't go into the television if it is not your own.

I know first hand on this one. Several years ago I bought a house that was two houses down from a Ham radio operator.

Well it appears the guy had not been using his rig for a while and all was fine. Until one day he decided to start chatting again.

I had noticed in the basement on the incoming phone line this large filter bank, but never really gave it any thought.

I quickly discovered what the filter was suppose to do, but didn't.

If we were using the phone and the Ham keyed his mike we could hear him talking. The speech was garbled but you could tell it was a man.... and it turned out it was the Ham.

Moving on.... I had just recently, at that time, purchased a new 31" tube TV. The 31" tubes hadn't been out that long.

The TV also had what they called synthesized rear speaker home theater sound system. For its day it didn't sound too bad.

But, that was before the Ham started chatting again. When ever he would key his mike and talk there would be video noise on the screen of the TV and the garbled sound of his voice through the speakers of the TV and the rear speakers of the family room. The cable length on the rear pair of speakers was about 30'.

Here is one you won't believe. The TV could be off and if the Ham was chatting you could still hear him from the TV speakers..... Faint but loud enough you could hear him. Especially late at night!

I tried ferrite chokes, I tried filter capacitors, shielded speaker wire, you name it, I tried it.

I finally gave up and disconnected the rear speakers and speaker cable wires from the TV.... No more Ham operator garbled voice over my TV. And most of the video noise on the TV screen disappeared.

The speaker cable was working as an antenna, or what ever else you want to call it.

Yes, speaker cables can be attennas, particularly when they are ribbons of wire with no criss-cross (rright-angle) geometry. Even short runs of parrallel wire ribbons can catch RFI.

Dave