[BC] Humming Preamps

[Ron Youvan]

> I'm still having issues with humming in all our mic, stereo, and phono 
> preamps. It's a buzzing sound that seems faster higher frequency than 
> 60 cycle hum. More like RF static. It happens in all 4 of our studio 
> booths on two floors. It's so bad we can't use our turntables. I got an 
> electrician to come out and he ran new ground wires for the building 
> service and switch panel and replaced old vibrating breakers. It still 
> hums. He suggests running 20 amp lines with isolated ground to plug 
> strips for each booth. Before I lay down another $800 does this sound 
> like it might fix our problem? Also do the high end $450 Furman or 
> Monster power conditioners work any better than the $150 Furman PL-8 
> rack mount conditioners we have? I'm starting to fear thousands spent 
> in a wild goose chase. By the way a Verizon tech had to install inline 
> RF filters to cut the humming and noise from our phone hybrids. I've 
> never met a building this noisy.

   It's easier to stop the interference with a capacitor than to isolate
every piece of equipment you have.  To locate the noise generator:
Try walking around the building wearing stereo headphones (like Koss)
that exclude external sounds, connected to a small transistor AM radio
tuned to 545 kHz (or some such) tuned for the most buzz. (Adapter required)
   Periodically rotate the radio for it's ferrite rod antenna orientation.
I suspect 120 Hz, could be a piece of computer equipment, like a printer
or some such or light dimmer - florescent fixture - sodium vapor light.
-- 
    Ron  KA4INM - My Florida property tax is 7 times what it was
                  3 years ago with no change on my part. OUCH!