Toubleshooting: Radio Noise

[hociman]

Originally Posted by Frog

For kicks I tried using a 3-2 prong plug converter on the TTPRO with no success.

Electricity could've given you a swift kick for this. tutt

It's a RFI or grounding problem. Start with the last piece in the chain and work backwards until you find the device that is picking up the station, then determine how to correct the fault.

[tINY]

Remember, too, that just because you have a 3-prong plug, there is no guarnatee that you have a ground in an old house.

The first thing I would do is verify that you have a ground, or call an electrician to look into it.



-tINY

[venuestudio]

Don't rule out radiated signals being conducted onto power and signal cables. This is like when a nob with a 1000 watt CB amp drives by and is picked up by the TV or stereo. The only way to find out absolutely is to snap a current probe on to the house wiring and use a spectrum analyzer to determine how much of the signal is being conducted onto the wiring. Because the signal is radiated it conducts on the wire as a common mode signal. Some equipment is better than others at attenuating common mode (common mode rejection).
Anyway you look at it, it is not easy to overcome. Possibly ferrites on the cables, possibly an overbraid on the cables (since it is an electric field you are battling). maybe a little of each.

Good luck,
Kent

[gitgrinder69]

I had a problem similar to this when I lived in Seattle. Even though the house was properly grounded, I would still get some wicked radio noise whenever I tried to record anything quiet. This was most likely the result of being only about a quarter mile from some big honkin' radio antennae. My final, though labor intensive, solution was building a 10'x10' cage out of chicken wire and grounding that. All recording done inside the cage was completely radio free. Sorta mad scientist, I know, but it worked.

Gabriel Horn

[max cooper]

One other reminder; if you're working with standard length cables (10' to 12') but you have some runs that should only be a foot, good idea not to coil that cable up nice and neatly and tie it off since it'll act as a coil.

[hociman]

Originally Posted by max cooper

One other reminder; if you're working with standard length cables (10' to 12') but you have some runs that should only be a foot, good idea not to coil that cable up nice and neatly and tie it off since it'll act as a coil.

Definite no-no for speaker cable!

[Frog]

Interestingly enough when I switch out the Baby Bottle to an Oktava 319 I get no radio noise. I have also found that moving the Baby Bottle mic around to different locations in the room drastically changes the level of the radio noise. Thanks for the suggestions though everyone. I will probably be having an electrician come over in the next couple months since were having something else worked on and I will ask about it then.

The chickenwire thing sounds interesting though.....I wonder if that'd work for me? I'm about a mile away from 3 huge tv/radio antennas.

[BVB]

Could also be a bad contact in the plugs(audio) that acts as a diode (remember the old cristal receivers)
I once had it long ago when recording a choir in bad circumstances , and running long cables.Solved it by pushing the XLR's interconnectors behind a rain pipe.Not very elegant,but it worked.

Greets

Paul

[venuestudio]

The chickenwire thing sounds interesting though.....I wonder if that'd work for me? I'm about a mile away from 3 huge tv/radio antennas.[/QUOTE]

should work just fine. You are building what is known as a faraday cage. The cage acts like the overbraid on shielded cabling, with the exception that you would be overbraiding the whole area. The same concept is used to build EMI quiet rooms to attenuate radiated electric fields.