John Sayers' Recording Studio Design Forum Archive

Well, I've finished the construction of my studio and wired it up, all the prepost requirements can be found here:

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=9800

and more photos, etc. . .here:
1867recording.com

But I am having a huge problem with the wiring, there is a ton of AM Radio in every circuit and most pieces of gear (including guitar amps with no DI's connected and the guitar volume down).

The wiring is as follows:

-there are 3 120V AC circuits, an audio, an instrument and a convenience circuit. The audio and instrument circuits are hospital (star grounded) and the convenience is a standard layout. All three (including the star ground) go to a sub panel which then feeds into another panel for the big building that I am in.

-The patchbay I made has grounding on each channel, but not connected globally or side by side. The shields are disconnected on all of the inputs of the individual plugs.

-There are no flourencent lights on these circuits and a variac is used as the dimmer.

There isn't really any hum, there is some high frequency noise, but nothing crazy. The huge problem is the AM Radio stations (yes more than one) that are showing up everywhere. They are coming of the mixer with all the channels off, really loud in the guitar amps with or without DI's connected, in a few compressors, and in a few mics connected directly to the board through mic snakes.

I tried a bunch of different outlets, closing the shields on the input plugs of some cables, but none of these things have made a difference.

The amount of radio and which piece of gear it shows up in varies a bit day to day, but it's always there, and the musicians are often actually hearing 3 different stations at once!!!

Do I try a monster power filter, a triplite isolator, an equitech balancer, etc. . .?

Help!
-Chris


EDIT:

I don't think it's AM radio now, I realized its a loop when I started recognizing the songs over and over again. It's like easy listening or elevator music or music that you would hear on hold on a phone. Hopefully that brings us closer to a solution. BTW it seems to be worse with tube mics and amplifiers. There are no windows and the place is all brick. It seems like it would be tough for radiowaves to get through so clearly. There is an airport not too far off, but this is so loud I would think the FCC would have a fit.

Not sure but here are some blind shots:

Maybe a power filter will actually help if the station is doing something wrong and sending carrier through the AC lines, which might happen though I'm not sure how common that is.

It could still be a bad transmitter over-modulating or distorting its carrier and creating stray carriers. A lot of commercial stations create sidebands off their main carriers which are reserved for vehicle radio and the elevator muzak that you describe for use in commercial spaces.

It doesn't even have to be AM. There's an FM station near my studio and their tower is so messed up it picks up on high-gain guitar amps here. FM!!!!

If you can move from building to building and duplicate the same problem, the chances lean toward a rogue tower and it might be time to look into whether or not the FCC would have an open ear.

As I wrote in another thread.
I saw an ad for a EMI/RFI Cell-pone interference tester.
From a web store called:
Cyberguys
Cellular Phone/emf Detection Meter
Item # 250 1304
$29.95

I have made 3 purchases from them in the past 3 years.
They seem to be OK.

Try these interference links:

http://www.kyes.com/antenna/interference/tvibook.html
http://www.kyes.com/antenna/interferenc ... cedex.html

http://strategis.ic.gc.ca/epic/internet ... 6086e.html

These link are from a 2006 thread on the AVS Forum.

I saw a situation once where people in an office were hearing elevator music on their phone system. Turned out that the local Muzak provider was operating out of the same building, and had a point-to-point radio link from there to the broadcast tower that was spitting out all kinds of garbage.