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500 hz problem

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Neumann Peluso:
In the process of setting up my new studio and have a problem with a hum. Tried everything from from ground lifts, plugging in each piece of gear individually, isolation transformer. An electrician came out and said the ground is fine. Tried different eqs and found the noise around 500hz. The noise comes through just about every piece of gear which worked fine in my previous studio. What could be interfering in that frequency? Has anyone had a similar problem before?

RawDepth:
Hi and welcome,

I have had a similar problem while running live sound in a nightclub. I later learned that if you have low voltage signal cables (mic, instrument, line level, sends, returns) running next to higher voltage cables (amp-to-speaker or AC power) they can cause some noise in the system. It is okay to cross them perpendicular but not to run them touching each other side-by-side for any distance.

Try not to tie your cables all together in tight bundles, unless you have them well sorted and compatible.

What kind of rig do you have? All separate analog gear? A computer with monitors? US or Europe?

stainless:
Welcome Neuman!

Have you tried unplugging all inputs to your board DAW? do you still hear it? or is everything connected?

if you have your system gain up... can you by any chance hear any radio in the background (no matter how faint)?

I had a problem with a constant "noise and at hi gain I could hear a radio station faintly in the background-

I had hardwired (in the wall) an low Z set of outputs to my power amps for the control rool... and had inadvertanly reversed pins 1 and 2 on 1 of the connections

it was only by disconnecting everything and connecting one thing at a time using a known/good/test cable that I found this... and it took me hours to find something that took less than 10 minutes to fix



don't know if that's it, but I'm guessing it's an induced signal (like Rawdepth suggested) or a cable acting as a poor antennae

where are you located 60Hz power or 50 Hz?

Neumann Peluso:

--- Quote from: RawDepth on May 06, 2009, 06:05:03 PM ---Hi and welcome,

I have had a similar problem while running live sound in a nightclub. I later learned that if you have low voltage signal cables (mic, instrument, line level, sends, returns) running next to higher voltage cables (amp-to-speaker or AC power) they can cause some noise in the system. It is okay to cross them perpendicular but not to run them touching each other side-by-side for any distance.

Try not to tie your cables all together in tight bundles, unless you have them well sorted and compatible.

What kind of rig do you have? All separate analog gear? A computer with monitors? US or Europe?

--- End quote ---

Hi Raw Depth,
Thanks so much for the advice. I'm located in the US running a tower and flat monitor running Sonar 6 and Pro Tools. I have some outboard gear in a rack and a 16 channel analog mixer which I intend to upgrade sometime soon. Most of my cables are relatively new or in very good shape but I'll still check them all. I have a wall & window between the control room and live room with a 16 channel xlr patch bay that has been hand wired all with twisted pair wiring. The patch bay is connected to the mixer with a brand new Mogami snake.
I did read somewhere about the power cables crossing the audio cables perpendicular so I have tried that. Much of the noise has come straight from the outlets even when the gear is plugged in on it's own, separate from everything else. I don't not here the noise during playback when only the computer, sound card and monitors are in use but have heard it in my mixer, headhone amp etc.

Thanks 

Neumann Peluso:
Hi Stainless and thanks so much. I had not noticed the noise at first when I was just playing back some music while setting up. When I started to test everything out and plugged in a mic is when all the trouble started and the more I investigated the more I heard the noise. We did hear some radio interference when plugged into one of my outlets in the wall. It wasn't super loud but any bit of it is too much.

I've heard the noise just from plugging in each piece separately (the mixer plugged into the wall with nothing else attached to it listening through the headphone jack) and even my headphone amp, not plugged into anything but the outlet and me listening through headphones. I even plugged my Otari tape machine into just the outlet and plugged my headphones in and could hear the noise there too. I don't hear it when the gain is turned low but when it's cranked, you can hear it plain as day. I'm located in the US.

Could It be a harmonic in the power perhaps? If so would you know how to kill it?

Thanks so much!


--- Quote from: stainless on May 06, 2009, 08:09:26 PM ---Welcome Neuman!

Have you tried unplugging all inputs to your board DAW? do you still hear it? or is everything connected?

if you have your system gain up... can you by any chance hear any radio in the background (no matter how faint)?

I had a problem with a constant "noise and at hi gain I could hear a radio station faintly in the background-

I had hardwired (in the wall) an low Z set of outputs to my power amps for the control rool... and had inadvertanly reversed pins 1 and 2 on 1 of the connections

it was only by disconnecting everything and connecting one thing at a time using a known/good/test cable that I found this... and it took me hours to find something that took less than 10 minutes to fix



don't know if that's it, but I'm guessing it's an induced signal (like Rawdepth suggested) or a cable acting as a poor antennae

where are you located 60Hz power or 50 Hz?

--- End quote ---

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