Loud background noise: cables picking up RF?

Is everything plugged into the same electrical outlet? Also look at this - Jensen Transformer - it might be a ground loop and this will eliminate that. Of course it is best not to have anything at all in the signal path but you already have a major problem.

Fully agree with dcstep's recommendations.You have to go for fully balanced system,using shielded and sielded IC..

You might also shield the unused RCA inputs usings specially made plugs{Cardas,Acoustic revive and the likes]

Lastly if you use any type of ionizers make sure they do not fire directly to your preamp input.
good Luck,and dcstep is right on the money

"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?"

In the previous post I did not address this part of your post. The power cords are not the problem. The wire feeding your outlets will still be there and that is not shielded. RFI filters immediately inside your preamp and amp should take care of that anyway unless it is of extremely large magnitude. In which case you may need an external RFI filter. Again - using an oscilloscope to troubleshoot will make life much easier. As to ic's picking it up - maybe. Any shielded IC should work fine. What is important is that the shield is complete and terminated correctly. Make a pair of IC's yourself, terminate the cable so that only one end of the shield will be connected to ground when it is hooked up - make that end the source end in each case. Radio shack best buy or whatever - no need to go to an expensive cable. To minimize any problems as to coverage of the shield (if you are using a mesh vs foil shield)- avoid sharp kinks in the cable. As a quick check- try adjusting the position of the cables that you do have hooked up now. The effectiveness of an antenna for a given signal depends on its orientation - if you start moving the ic's while listening - as if adjusting an antenna - and you hear a change - then yes, your ic's are definitely picking up the interference.

You've gotten lots of great advice here. Please follow up to let us know what you figure out.

If the ICs are a big help, then you're in one of those situations where almost every improvement you make will be noticeable. If that's the case, then I'd recommend going fully balanced if your pre-amp doesn't already allow it. Think of RFI with every IC and cord selection and consider putting a conditioner in the line. These improvements will be small relative to fixing your initial problem; however, when your bathed in RFI then plugging every hole is important.

Dave

You are not hearing transmitted RF through your speakers - you cannot hear RF and your speakers cannot reproduce it - outside the frequency range for both.

His audio system can work like an antenna and receiver. And long speaker cables can work as an antenna and the transmitted RF will be heard through the speakers.
Example
You might want to check out the archives here on Agon.

I do think in the case of Dawgcatching if the sound he is hearing from his speakers is static, just my 2 cents, I don not think it is caused from the communication tower antennas. But no guarantees....

Static can also be caused from a HV cold solder joint or point on a circuit board with in the preamp or the power Amp. Could be a bad connection on a tube socket for example.

Unless Dawgcatching joins in the discussion it will be very hard to help diagnose the problem.