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[joeq]

I have an old tube EQ- sort  of  a Pultec copy that I recently brought home to use in my home studio.   I had it on the rug when I was wiring it up and I ended up using that way last night- just leaving it lying there on the floor,  lazy bastard that I am.

When the session ended I screwed it into the rack and went to bed

Today when I turned it on I heard a hum-  I thought maybe I had pulled some wires loose but no- everything was the same

after some experimenting it turns out the unit will hum when it is in or near the rack.  It does not have to be touching the rack rails.   just starting to slide it in will cause the hum.      lying it on the rug a few feet in front of the  rack it is just fine.     twisting it in the air near the rack I could make the hum better or worse depending on the position-  like a guitar.

Inside the rack are two reverb units, an RNC and a power strip with all their wall warts.    could the wall warts  be causing the problem?

Unless I can find a solution this unit may have to go into its own rack or stay there on the rug!     Any ideas?

[Rail Jon Rogut]

Move the wall warts away.. they're used for that exact purpose.. to move them away from the audio -- instead of using a costlier power supply design.

Rail

[John Bordon]

Wall warts are my first guess always. But I found the source to beat all sources.... A computer monitor!   LCD monitors don't create hum but their lesser counterparts do!  Recreate the hum.... unplug your wall warts one by one (some are well made) then turn off your monitor!