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10 • SM-500 USER GUIDE
BALANCED XLR OUT
The Balanced Out is a true balanced output and serves two functions. In the “Direct” position, the
XLR is essentially an active tube direct box. The signal is taken directly from the input jacks. No con-
trols on the front panel affect the sound, volume or content of the signal. In the “Line” position, ALL
controls on the front panel (with the exception of the Effects Blend and Master Volume) function and
affect the signal. Output level in the “Line” position is determined by both the Gain and XLR pad.
When using this switch, make sure it is all the way to one side or the other and not in a “half way”
position, as this could result in no output.
The “Line” position can be used for recording directly into a tape machine as well as going directly to
the studio board. An external power amplifier with a balanced input can be driven in the "Line" mode.
Pin out for the XLR connector are as follows:
Pin 1 = Ground Pin 2 = + Pin 3 = –
The SM-500 is compatible with Phantom Power-equipped mixing consoles.
XLR PAD AND GROUND LIFT
The XLR pad adjusts the level (volume) appearing at the XLR connector directly below in either the
Line or Direct mode. Volume increases as the control is turned clockwise.
If you are in the “Line” position and change the Gain control on the front panel, the level will also
change at the balanced output. You may readjust the XLR pad if necessary without affecting any
other function.
A ground lift is provided for the record out XLR Output. It is built into the XLR Pad. With the knob on
the XLR pad in the “In” position, the ground to pin one is engaged. Pulling the knob to the out or
“Ground Lift” position will interrupt or defeat the ground on pin 1.
If a persistent hum exists after trying both positions of the ground lift, there is probably a mis-wire or
bad ground in the feed lines to the board or console or a dirty or miswired AC socket. SWR recom-
mends the purchase of an AC wall socket tester which can identify proper wiring (available at most
hardware stores). These inexpensive devices are a simple way to protect you and your equipment
from faulty electrical systems.
LINE OR MAINS FUSE
The size and rating of the line fuse is 3AG, 7 amp, slo-blo. NEVER replace this with a fuse of a higher
rating as it will void your warranty.
INTERNAL FEATURES
COOLING FAN
The SM-500 contains an internal thermostatically controlled cooling fan. When the temperature of the
heatsinks reach 50 degrees centigrade, the fan will automatically turn on and remain on until the
heatsink cools down to approximately 40 degrees centigrade. This greatly reduces component fatigue
and increases reliability.
For proper ventilation, make sure that all of the SM-500’s vents are unobstructed when installing it in
a rack case.
Note: At low volume levels, the cooling fan in the SM-500 may be audible.