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trying to find the needle in a
heystack ... here's some more advice to avoid hum in racks ( besides what's
already been said ):
- find out which of your rack units
causes the hum ( ... it sometimes helps to put it in another place inside the
rack, because of the position of the transformers inside the units ...
)
- insulate the rack units chassis
from each other and from the rackrail they're connected to ( by using tape to
keep the front plates apart from each other, and "humfrees" or plastic rings for
the screws )
- keep wallwarts inside the rack as
far away from each other as possible, as well as from the transformers
of non-wallwart units and from line cables
- the whole rack, together with the
other gear u're using, needs only one ground connection / should have only one
and the same mains connection
( if u're rich, use a power conditioner ... i.e. Furman et. al.
)
- when using a mixer and it's aux
lines this may cause a doubling of ground connections ( "humloops" ) ... if
so, u need special patch cords with the ground/shield disconnected ( the
equipment inside ur rack maybe seen/connected as ONE unit ) - but better talk to
a pro before u start disconnecting grounds, always keep in mind that u need ONE
GROUND CONNECTION TO BE SAFE ! ! I will not take any responsibitity if u make a
mistake and grill either urself or ur equipment !
- u may also use special transformers
which separtate the ground ( in a way almost like a DI box ) for each of ur rack
units.
this is the best solution, but
expensive ...
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