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SM-900 USER GUIDE • 3
THERMAL PROTECTION:
Both natural convection and thermostatically controled forced air (cooling fan). The internal fan is
set to operate when the heatsink reaches 50 degrees centigrade and will automatically shut off
upon cooling. This allows silent operation in the studio or other low volume conditions.
COUPLING CAPACITORS IN SIGNAL PATH (input to output jacks):
Quantity: 5
Type: High-grade metallized polyester, made in Germany
TUBE COMPLEMENT: One (1) specially-selected 12AX7 vacuum tube (valve).
CHASSIS MATERIAL: All aluminum for light weight and purity. Steel-reinforced rack corners.
ASSEMBLY: Virtually every step of the assembly procedure of the SM-900 is done by hand, in-
house, at SWR Sound in Sun Valley, California, USA.
CUSTOM PARTS: The chassis, extruded heatsinks, printed circuit boards, power transformer, own-
ers manual and shipping cartons are all manufactured in California. Our custom rotary potentiome-
ters are made by Noble, Japan.
SIZE (measured from the rack ears back): 19" W x 3.45" H x 13.75" D (482.6 x 37.63 x 349.25
mm)
WEIGHT: 22 lbs. (9.98 kg)
FRONT PANEL FEATURES & OPERATING PROCEDURES
EQ FOOTSWITCH JACK
For remote selection of the equalizers, insert the footswitch that came with your SM-900 into this
jack. Installing the footswitch will automatically DISCONNECT the manual EQ slide switch located
directly above the Aural Enhancer.
Depressing the footswitch will silently select the settings you have decided upon on either EQ
bank 1 (bottom row, white knobs) or EQ bank 2 (top row, black knobs). Each bank consists of 3
bands of semi-parametric equalization featuring dual concentric knobs. The INNER knob adjusts cut
and boost, and the OUTER knob is for selection of frequency. When you have selected EQ 2 (top
three bands), the RED LED located just to the left of these will light. When this LED is OFF, EQ 1
is active. This LED lets you distinguish which band of EQ you are currently using from a distance.
EQ 1+2 is NOT obtainable with the footswitch.
The BASS and TREBLE controls are INDEPENDENT of either the footswitch or the manual EQ slide
switch. (See “Tone Controls” for further details.)
Disconnecting the footswitch will automatically re-activate the manual slide switch.
INPUT JACKS
Passive/Active Input
A “passive” instrument has no built-in preamp and does not use a battery. An “active” bass, on
the other hand, utilizes a battery operated preamp, either for gain, tone controls, or both. Although
labeled “Passive,” the Passive input jack will work with all instruments that have a maximum out-
put of less than 1 volt RMS.
Generally speaking, try the Passive input jack first. If you hear a small amount of distortion and