SMc Audio SM-500SM-500 - Manual (Page 9)

SPEAKER GUIDELINES
• DO NOT connect speakers with a total impedance
load below the minimum rating of your amplifier to
prevent damage to your equipment.
• ONLY connect speakers with a total power handling
capacity that is above the power output rating of
your amplifier to prevent damage to your equipment.
• ALWAYS switch your system power OFF before
connecting or disconnecting speakers.
• ONLY use unshielded speaker cable of 18 gauge or
heavier (such as 16 or 14 gauge) for speaker
connections. Shielded instrument cable WILL NOT
work and may damage your equipment.
• ONLY connect one amplifier to your speaker enclosure(s).
Two amplifiers WILL NOT work and may damage your
equipment.
Use the impedance ratings on your amplifier and speakers
to determine if a particular combination of speakers is
appropriate for your amplifier. NOTE: All SWR ® bass speaker
enclosures, as well as most others, are wired in parallel
(NOT in series), therefore, these guidelines apply only to
parallel speaker connections.
Shown here are the total impedance load
calculations for various speaker impedance
combinations. Ideally, the total impedance load
of your speakers should equal to the minimum
impedance rating of your amplifier. Operating
below the minimum impedance rating can overheat
the amplifier and cause damage. Operating
above the minimum impedance rating will
reduce the amplifier’s maximum power
output.
Notice that different combinations of speakers
can equal the same total impedance load. If
their impedances are the same, each speaker will
receive equal power from your amplifier. However, if
impedances are not the same, speakers with the
lowest impedances will receive the most power. For
example, if you connect an 8–ohm and a 16–ohm speaker
to the same output, the 8–ohm speaker will be twice as loud
as the 16-ohm speaker. Take this into consideration when
calculating power handling capacities and when positioning
your bass speaker enclosures.
For an in-depth discussion of impedance and power rating
issues, go to swrsound.com and click on “Press,” then
“Articles,” then “Plug and Play: Setup Tips for Amps and
Speakers”—an article by SWR ® founder Steve W. Rabe that
ran in the August ’92 issue of Bass Player Magazine.
3. Accompaniment - Connect a CD player or drum
machine to either the Mono Return or Stereo Return
jacks according to the Mode of Operation {P}. Control
accompaniment volume at its source and with Effects
Blend {J}.
V. TUNER OUT - Plug in your instrument tuner. Use the
Speaker switch {M} to mute audio output while tuning.
W. BALANCED OUTPUT - A fully featured, true
electronically balanced, XLR output; suitable for
studio and live performance mixing consoles:
•LINE / DIRECT - Supplies the Balanced Output with
signal that either includes or bypasses the onboard
tone shaping circuits:
LINE (Include EQ) DIRECT (Bypass EQ)
•GROUND / LIFT - Disconnects the Balanced Output
ground connection (pin-1) which may reduce ground
loop noise from non-standard wiring. Normally leave
this switch out:
GROUNDED (normal) GROUND LIFTED
•XLR PAD - Adjusts the signal level of the Balanced
Output jack to accommodate a variety of equipment
connections.
XLR Wiring (American Standard):
1 Ground
2 Positive
3 Negative
✧ s s w w r r s s o o u u n n d d . . c c o o m m ✧
R R R R e e e e a a a a r r r r P P P P a a a a n n n n e e e e ll ll —continued 9