Toubleshooting: Radio Noise
Frog
Thread Starter
#1
3rd August 2005
Old 3rd August 2005
  #1
Gear interested
 

Thread Starter
Question Toubleshooting: Radio Noise

Greetings Slutz,
Long time reader, first time poster.

I recently bought an older house (1927) in Milwaukee, and proceeded to setup my modest studio in one of the smaller bedrooms.

Upon getting together with a buddy guitar-player to make some noise I hooked up the signal chain as follows:

Baby Bottle>Focusrite TTPRO (plugged into a Furman power conditioner)>Aadrvark Q10.

Turned up the headphone fader knob, and here I am listening to a damn clean sounding radio. WTF! For kicks I tried using a 3-2 prong plug converter on the TTPRO with no success.

From what I've found on here its likely that this is caused by the wiring in my house. Ain't that dandy?! I'm sure cheap to fix too.

Are there any other possible solutions to a problem like this? Does anyone have experience beating this?

Thanks in advance.
#2
4th August 2005
Old 4th August 2005
  #2
Lives for gear
 
hociman's Avatar
 

Thumbs down bad idea

Quote:
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.
#3
4th August 2005
Old 4th August 2005
  #3
Gear Guru
 
tINY's Avatar
 



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

#4
8th August 2005
Old 8th August 2005
  #4
Gear interested
 

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
#5
9th August 2005
Old 9th August 2005
  #5
Gear interested
 

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
#6
9th August 2005
Old 9th August 2005
  #6
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max cooper's Avatar
 

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.
#7
9th August 2005
Old 9th August 2005
  #7
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hociman's Avatar
 

Exclamation yep

Quote:
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
Thread Starter
#8
25th August 2005
Old 25th August 2005
  #8
Gear interested
 

Thread Starter
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
#9
25th August 2005
Old 25th August 2005
  #9
BVB
Gear maniac
 

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
#10
30th August 2005
Old 30th August 2005
  #10
Gear interested
 

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.
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