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Chapter 2: Connections
RA150/300/500 Reference Manual 11
refrigerators, coffee pots, toasters, air conditioning,
or stage lighting, plug the RA150/300/500 into a
different circuit with a lesser load.
OPERATING ENVIRONMENT
T
EMPERATURE CONSIDERATIONS
IN
RACK MOUNTING
The RA150/300/500 can be mounted in an
equipment rack (taking up 2 rack spaces or 3 spaces
for the RA500), placed on a shelf, tucked away in a
vocal booth, etc. When you install it, keep in mind
that heat is the major enemy of electronic equipment.
Fortunately, the RA150/300/500’s protection
circuitry will not allow the unit to run hot enough to
damage any of the circuitry. However, sustained
high-temperature operation sufficient to cause
limiting will adversely affect the sound quality, and
eventually the amplifier will shut itself off for as
long as the excessive temperature conditions exists.
The RA150/300/500 has extensive heat sinking to
minimize overheating, as well as eliminate the need
for a ventilating fan. The latter feature is crucial for
the cramped control rooms typically found in
smaller studios; any fan noise would interfere with
the mixing or monitoring process.
But the RA150/300/500 must be installed so that
its heat sinking is allowed to do its job.
Please observe the following:
• The RA150/300/500 is designed to perform
properly over a range of ambient temperatures
from 0° C to +50° C (32° F to 122° F), in up to
80% non-condensing humidity. These are not
absolute limits, but Alesis cannot guarantee that
the RA150/300/500 will meet its published
specs if operated outside of these ranges. If
necessary, use a fan to blow air over the
RA150/300/500 and promote cooler operation.
• Prevent the side heat sink fins from becoming
obstructed. There should be enough airspace
around the amplifier for it to “breathe.”
• Always allow adequate ventilation behind the
RA150/300/500. Do not seal any enclosure that
holds the RA150/300/500.
• Never throw a coat or other flexible fabric or
covering over the top of the amp when it’s in
use.
• You may wish to leave an empty rack space
above or below the amp to promote good air
flow. If multiple amplifiers are mounted in the
same rack, there should be at least one rack
space left between them; solid blank panels may
be used to fill the spaces, but perforated grilles
used as fillers will help exhaust the hot air from
within the rack.
OTHER RACK MOUNTING TIPS
• Due to the RA150/300/500’s weight (from 15 to
28.5 lbs.), it’s a good idea to mount it in the
bottom of the rack frame. Support of the back
of the unit may be necessary for portable or
road use.
• Alesis Reference amplifiers are well shielded;
however, mounting low-level electronics some
distance away from power amplifiers is
common practice to reduce the possibility of
electromagnetic interference into the low level
units, which may sometimes be unusually
susceptible to picking up such radiation.
When wiring a rack, it is good installation practice to
route all AC wiring along one side of the rack
and all audio wiring along the other side to avoid
coupling AC-borne interference into the audio.