Uninvited radio station interference

>>" I can hear it when the amp is on and the pre is off, but its so low I wouldn't have noticed it."<<
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How close do you live to the Radio transmitting Tower/s?

Not knowing your amps, do they have a metal vented cover over the tubes and electrical components? This cage is an RFI shield, a Faraday cage. Do you have them on the amps?

I assume your speaker cables are short because of the mono amps, is that correct? Long speaker cables will act as an antenna where radio transmitting towers are in close proximity to audio equipment and their ics and speaker cables.
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>>"When the preamp is on it is louder and noticeable. When the volume on the pre is turned up, even full, it is not any louder."<<
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Is this with any source input selected? Disconnect all input source ICs from the preamp, does it make any difference?

What make is your preamp, manufacture? Do you have any covers off? Farady cage.

Do you have any Ferrite Beads, RFI filters? Try them on the power cord of the preamp. RFI can be in your homes electrical wiring, one big antenna, and interring the preamp through the power cord.. Bad thing about Ferrite beads they can effect the sonics of the preamp.

The Stealth M-7 ic's are "standard double shielded" (from the website).

Do you have any other shielded ics you could try?

I previously had the same problem. I suspect your unshielded speaker cable is the prime culprit. Sometimes changing the placement of your equipment can make a difference as well.

Jea48, I removed the ic's from the pre inputs, no help.

I added a MIT powercord with, I think, ferrite at both ends, to the preamp, no help.

I ran the amp with the pre off, no help.

When I disconnet the IC from the power amp, NO RADIO!

I guess this eliminates the zip cord as the problem.

The preamp is a DEQX three way crossover and pre that I need in the system, but the radio seems to be comming from it. It's pluged into a Power Wedge 116. I'll try moving some of the power cords around to see if this makes a difference. Any other thoughts?

Thanks,
rloggie

Well, after trying several variations on plug ins I lifted the ground on the preamp and the radio is off:) Thanks for getting me started and for all responses.

Robert

While it may solve your radio problem, I am not so sure if lifting the ground on your preamp is a good idea for electrical reasons.

You may now have a system that is not grounded to anything anywhere. It could be a shocking experience if you become the ground if/when you touch the wrong thing.