Is it a ground loop ?

[ISedlacek]

I placed Lavry AD DA into the rack surrounded by Millennia, Lexicon etc. WHen I connect Genelecs, there is immediately a slight hiss-whistling flowing and changing noise coming from the monitors (not related to any source and any volume). When I connect Genelecs to Apogee or Lynx (which are on the table, not in the rack, i.e. outside the other gear skeletons), there is no such a noise. I remember when I used to have Digi 002 in the rack, after connecting Genelecs directly, there was immediately a big (low) hum. ALso when connecting Lexicon inserts through analogue send-returns. But there was always very low hum, now it is hiss and whistling. Could it be the same problem ? Any way to solve it ?
I was told that Neutrik NTL 1 (line separating transformer could maybe help).
But I really don´t know ...
An advice would be highly apprecciated

[thenewyear]

Why not try taking the Lavry out of the rack to see if that eliminates the problem??

If that did the trick you could then invest in a set of Humfrees (the little insulated rack bolts) that should hopefully break the electrical connection between the AD and the rest of the rack.

However in practice I have found heavy equipment in a rack can rest on the piece below it hence creating another electrical connection. This can be broken by inserting a thin sheet of plastic between the two (be careful not to cover any vents).

As always if you start with clean, steady mains from a single source most of these problems are easy to solve.

[thenewyear]

Why not try taking the Lavry out of the rack to see if that eliminates the problem??

If that did the trick you could then invest in a set of Humfrees (the little insulated rack bolts) that should hopefully break the electrical connection between the AD and the rest of the rack.

However in practice I have found heavy equipment in a rack can rest on the piece below it hence creating another electrical connection. This can be broken by inserting a thin sheet of plastic between the two (be careful not to cover any vents).

As always if you start with clean, steady mains from a single source most of these problems are easy to solve.