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12 • SM-900 USER GUIDE
SM-900 models with a serial number of 2706 and greater are compatible with Phantom Power-
equipped mixing consoles.
LINE/DIRECT SWITCH
In the “Direct” position of this switch, the XLR is essentially an active tube direct box, and the
signal is taken directly from the input jacks. Controls on the front panel DO NOT affect the sound,
volume or content of the signal. In the “Line” position, ALL controls on the front panel (except the
Effects Blend and Master Volume), affect the signal. Output level in this position is determined by
both the Gain and XLR pad controls.
Make sure this switch is set all the way to one side or the other (not positioned somewhere in
between, which could result in no output).
XLR PAD AND GROUND LIFT
The XLR Pad control adjusts the signal level appearing at the XLR Balanced Output in both the
Line and Direct modes. The level is increased 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. The XLR pad can be readjusted without affecting any other func-
tion.
A ground lift is provided for the XLR Balanced Output; it is built into the XLR Pad. When the knob
on the XLR pad is in the “In” position, the ground to pin 1 is engaged. Pulling the knob to the
“Ground Lift” position (out) will interrupt or defeat the ground to pin 1. If a persistent hum exists
after trying both positions of the Ground Lift function, there may be a problem with the AC voltage
or possibly a dirty AC line.
TO TUNER INPUT
The “To Tuner” input jack allows the user to connect an instrument tuner and tune up without hav-
ing to unplug and go back and forth from amp to tuner. This feature is totally isolated from the
rest of the preamp and will function regardless of the settings of any control on the front panel.
Being isolated on a side chain avoids loading down of the instrument, which can cause a loss in
dynamic range.
To use this feature, connect a shielded patch cable from the “To Tuner” input to the INPUT on your
tuner. Turn the amplifier on and you’re ready to go. If you don’t want to monitor your sound while
tuning up, turn down the Master Volume.
CROSSOVER HI AND LOW OUT JACKS
These jacks provide a LINE LEVEL output that can be sent to either an external power amp or the
internal power amps of the SM-900 via shielded patch cables. You cannot connect speakers direct-
ly to these outputs (see diagram on page 19).
Present at the Low jack are all frequencies below the point set by the Crossover Frequency con-
trol on the front panel. Present at the High jack are all frequencies above the point set by the
Crossover Frequency control. ALWAYS use a high-quality shielded patch cable that is as short as
possible for bi-amp connections.
BI-AMPING WITH THE SM-900
Bi-amping is the process of driving two separate cabinets, one for high frequencies and one for low
frequencies, with separate power amplifiers. We have found bi-amping to be most useful in situa-
tions where the user wants to run effects on the high frequencies while keeping the low frequen-
cies “dry.” This allows the user to utilize effects without sacrificing a solid bottom end.
To bi-amp with the SM-900, run patch cables from the Crossover Outs to each of the Stereo