Noise problem

brain_11 · Post by **brain_11** » Fri Oct 14, 2005 3:29 pm

I have several MFs but always had (and still have) the same problem: noise. I use common ground for all of my equipment (same outlet). Voyagers and other keyboards and even the rack that houses the mixer, MFs etc are grounded. Switching from the regular wall wart power supply to a digital one (Power-all) helped a lot, but the MFs are still the noisiest equipment in my setup.
There might be a lot of radio frequency around, because when I “shield” the setup with my body the noise is radically reduced. I tried to use a Faraday-cage around the rack to reduce the noise but it did not help. If I touch some plugs on the MFs, the noise is reduced.
I wonder that the reversed polarity power supply (negative ground) can cause this problem. The power supply is not grounded, but the housings of the MFs are.
So what do you think, is it ground loop, or radio frequency? Any thoughts how to eliminate it?

falseface11 · Post by **falseface11** » Sun Oct 16, 2005 6:28 pm

What did you ground the faraday cage to?

brain_11 · Post by **brain_11** » Sun Oct 16, 2005 8:42 pm

I grounded the Faraday to the heating pipelines. I measured that the pipeline was on the same ground as the electrical outlet.

falseface11 · Post by **falseface11** » Mon Oct 17, 2005 7:56 am

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1) do you have this problem with the voyager alone? (test through

Headphones)

2) have you tried an alternative ground for the faraday cage?

3) have you recorded the noise and have a sample of it / or run a

spectrum analysis on it (if you have a sample i will do so). it may be

helpful to know the frequency of the noise( the freq is good to know

especially if you call Moog Music for tech support)

4) find a piece of equipment that does not have this problem on its own.

you might find that there is one piece of equipment that needs to be

on its own circuit(quite possibly the amplifier/P.A.)

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brain_11 · Post by **brain_11** » Mon Oct 17, 2005 1:09 pm

The Voyager is fine, no noise is coming out of it. I tried with other keyboard just in case resulting the same problem.

All the MFs of mine, but especially the MF 103 are noisy. I'll analyze the frequency, but it is not the ussual 60Hz. There is a high frequency component (~ 10KHz I guess) and there is another louder one, which is modulated by the MF. If I bypass the MF, only the high frequency component remains (less annoying).

The noise is still there even if no audio input ic connected.

I'll try to ground the Farady cage to something else (rack).

falseface11 · Post by **falseface11** » Tue Oct 18, 2005 4:07 am

i was also wondering if you have a vx-351, if so is there additional noise present/noise that dissapears when you are routing controls to the moogers

falseface11 · Post by **falseface11** » Tue Oct 18, 2005 4:12 am

also i drove a 6' stake into the back yard and grounded my entire studio circuit from the breakerbox to it. it worked... there is soo many variables with these type of problems that you never know what will work!
Good luck!!