Audio Research Definition DSi200, Owner'S Manual, Page: 14 / 14

only could this cause overheating, but hum may be
introduced into the preamp from the proximity of the am-
plifier's power transformer. Do not stack components or
other objects directly on top of the DSI200.
3. Do not place or operate your preamp on a soft or
irregular surface such as a rug. This will prevent proper
ventilation.
Operating Procedure
Start-Up:
1. Secure all rear-panel connections between DSI200, pow-
er amplifier(s) and input sources.
2. Plug three-prong power cord from rear of chassis into
grounded AC wall outlet. The Power switch defaults to
“off” when the unit is plugged into a power receptacle.
3. Press power switch (either remote or front panel). “Mute”
will will flash in the display window for approximately
50 seconds, then cease flashing and remain in the
display. Press “Mute” to initiate operation.
4. Select input source, then BAL or SE as necessary.
The DSi200 should be turned on a f t e r the source compo-
nents of your system. If the DSi200 is turned on before
other components, it will amplify any extraneous turn-on
noises those components might generate, which could
potentially damage the loudspeakers.
Good operating
practice dictates that the amplifier should be turned on
last, and turned off first in an audio system.
PROCESSOR (PROC): May be selected by button on remote
control. Selects external A-V (home theater) processor as
input source and controller of volume level for R and L
channels provides Unity Gain when this input is selected.
When engaged, “PROCESSOR” will appear in the display,
and the volume control is not adjustable because gain is
fixed. The DSi200 will also mute the input after “PROC”
is engaged.
If electronic crossovers or other AC powered equipment is
used with the DSi200 it may be necessary to use “ground
lifter” adapters on the power plugs of that equipment to
minimize system hum. Generally, the lowest hum is
achieved when the only direct connection between audio
common “ground” and true earth ground occurs in the
preamplifier, through its grounded power cord. Other
equipment in the system should have some form of isola-
tion to prevent ground loops and associated hum.
The vacuum tubes inside your DSi200 are quality 6H30
dual triode tubes and with normal use should not need to
be changed for approximately 4,000 hours of use. Replace-
ment tubes should be of equivalent quality and are
available from Audio Research. Note that tube numbers
(V1 and V2) match printed numbers next to tube sockets
on circuit board.