SWR SM-900 User Manual page 14

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 function.
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 having 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 directly to
these outputs (see diagram on page 19).
Present at the Low jack are all frequencies below the point set by the Crossover Frequency control
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 situations
where the user wants to run effects on the high frequencies while keeping the low frequencies "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 effects
returns (i.e., one cable from the "High" out jack to the Left stereo effects return, and one cable from
the "Low" out to the Right stereo effects return). In this configuration, connect your low end speakers
(woofers) to the Right speaker output jacks, and your high end speakers (midrange/tweeters) to the Left
speaker output jacks. Use the Balance control on the front panel to even out the highs and lows (see
diagram on page 19).
Note: The Effects Blend control must be in the fully "wet" position. If not, you will be getting full-
range signals sent to your power amps and NOT the signals sent by the electronic crossover.
Similarly, the Power Amp Assign switch MUST be in the "Stereo" position.
An effects unit may be placed in between each of the Crossover Out jacks and the Stereo Effects Return
jacks. This allows you to run an effect for just the lows or highs (or both) using multiple stereo effects
units. The MONO effects return is BEFORE (PRE) the electronic crossover circuit.
This allows the user to insert a mono effects unit that will be sent to both the Low and High output
jacks.
12 • SM-900 USER GUIDE