Effects Loop - SWR SM-900 User Manual

A diagram showing proper connections for bi-amp operation appears on page 19.

EFFECTS LOOP

Both Mono and Stereo Effects Loops are provided on the SM-900, though it should be noted that both
cannot be used simultaneously. Always use high quality shielded patch cables for all connections
between the amplifier and your effects units. We recommend that the cables be as short as possible.
The amount of signal present at the Effects Send jack is determined by the setting of the Gain control
on the front panel. If your effects unit is overloading and it does not provide for compensating incoming
signals (such as an input volume, or switches marked +4 or –10), you may turn down the Gain control
to avoid this condition. If your effects unit has input level adjustments, they should be set for either 0dB
or +4dB.
The Master Volume may be used to recover losses in gain caused by some effects units.
Use the Blend control to adjust the amount of "effects" with the natural signal from your instrument.
Note: You will not hear any sound from your effects if the Effects Blend control is in the fully
counter-clockwise ("dry") position.
To use the mono Effects Loop, run a shielded patch cable from the "Send" jack of the SM-900 to the
input of your effects unit. Run a second patch cable from the output of your effects unit to the mono
effects return jack. Now adjust the Effects Blend control for the mix you desire.
To use the stereo Effects Loop, run a patch cable from the "Send" jack of the SM-900 to the mono
input of your stereo effects unit (either the left or right input—check the effects unit and/or its owners
manual). If your effects unit does not provide a mono input, get a "Y" mono cord from your local music
or electronics store. Plug the common end in the effects Send jack and the other two ends in the left
and right inputs of your effect (see diagram, page 20).
If you wish to use just the internal power amps in the SM-900, the Effects Return jacks will serve as the
"inputs." Insert your MONO signal source in the MONO Effects Return jack. This will send the source to
both power amps. If you have a stereo source, plug the left and right outputs into the corresponding
Effects Return Jacks. If you want to use just one side of the amp, use the LEFT CHANNEL ONLY (the
thermostat that regulates the fan is located on the left side).
STEREO/BRIDGE POWER AMP ASSIGN SWITCH
To run your amplifier in the stereo mode, move the Power Amp Assign Switch to the "Stereo" (top)
position. You will need to use the speaker outputs marked "Left" and "Right." To run the SM-900 in
mono, move the switch to the bottom "Bridge/Mono" position. Your speakers must then be plugged into
the Speakon jack marked "Bridge" (see diagram, page 17).
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We recommend using caution when connecting your system in "Bridge/Mono" mode. Because the
SM-900 delivers 650 watts RMS minimum into 8 ohms and 900 watts minimum into 4 ohms, damage
can result very quickly to speakers not capable of handling this much power. If you have or need to use
a single enclosure with a power handling capacity of less than 650 watts (8 ohms), or 900 watts (4
ohms), run the amp in Stereo and use just the LEFT speaker output. No harm will come to your
amplifier by leaving the Right speaker output disconnected.
Minimum Load in the Bridge/Mono mode is 4 ohms.
Minimum Load in the Stereo mode is 2 ohms per channel.
SPEAKER FUSES
Speaker fuses are provided to protect your speakers in the unlikely event of a power amp failure,
incorrect connection procedures, or impedances below recommended ratings. Size and rating of the
fuses are 3AG, 10 amp, fast-blo. Do not defeat the purpose of this feature by using a higher rated fuse
SM-900 USER GUIDE • 13