Infinity Reference Standard I Instruction Manual page 6

Feedback
Tf, after taking care in positioning
your RS I speaker system, you find the
bass response is "boomy" and lacking
"tightness," or you hear a rumble when
playing
records, or
you notice excessive
movement of the woofer cones, the cause
may be acoustic feedback. This means
that
the vibrations
from your
speakers
are being picked-up by the cartridge
of your turntable. Because of the
extended low'frequency response of the
RS I, isolating
the turntable
fron these
vibrations calls for considerable care.
In general, make sure that the
turntable is placed
on
a heavy, solid
support,
as far away
from the
speakers
as possible. Some combinations of
turntable, tone arm, and cartridge are
more apt to encounter feedback than
others. If you continue to experience
difficulties after some experimenting,
ask
your Infinity
dealer
for assistance.
-Hum
If you should experience an audible
50/60 cycle hum in your speakers, use a_
two-prong adapter (commonly called a
cheater or floater) on the A.C. power
cords of your components that have
three-prong plugs, one at a time, until
the hum.is eliminated. If hum persists,
float all of your components EXCEPT ONE
(to keep your system grounded). Try
inverting the two-prong plugs of your
components as well. Also, check all
connections (especially the turntable's
ground), and exchange the audio
connector cables with ones that are
known to be good; replace defective
cables if necessary. If hum still
persists, consult your Infinity dealer ™
or Infinity's customer service
department.