Help with grounding in/outs and S/Rs

[sjaltenb]

Hello...

I need help with grounding issues on my large multieffects board. It is a wooden enclosure sprayed with shielding paint. All the jacks are neutrik enclosed jacks mounted on a steel plate.

I have 4-5 S/Rs on the board, two inputs, and three outputs, about a dozen FX boards, and each will be powered by a single transformer with about a dozen windings feeding regulated power supplies.

So this leads me to my grounding scheme. I have NO idea where to begin. At first, I thought i would simply bus all the sleeves of my jacks together and ground them to a star ground connected to the AC120 ground wire, which is screwed into the enclosure. This cuts the really loud BUZZZZZZZZZ but still leaves some residual buzz. I did not have any FX connected or anything, once I bussed all the jack sleeves together and grounded them to the negative on a 9v power supply (which helped a little) i simply jumpered the tips of my in and out jacks with a test lead.

I was dissapointed to find that in a setup this simple I still had slight buzz. its not horrible, but its not usable. I then ran another experiment with a volume pedal in one of the Send and Returns and found that grounding the sleeves of the S/R jacks does Nothing whatsoever good or bad. So im assuming I will not ground those. It also does not make a difference if i only ground the input, or only ground the output, as long as one of them is grounded.

I guess I am just worried that if i cant simply go in-out of two jacks without noise now, I shouldnt even begin to start grounding the entire board! I always figured I would ground the actual FX boards to each power supply individually...

Help!

Heres some pics for those not familiar with the project:




and the input/output/SR panel: