Subwoofer; Frequency - Mackie M1200/M1400 Owner's Manual

"square off," and the average power going into
the speaker is roughly double that of a sine
wave. Square waves sound awful, and could
possibly damage your speakers and/or your
reputation.
The LIMITER is especially handy when
you're working with loud output levels. Having
the signal spikes (kick drum, for instance) at-
tenuated a bit can actually increase the
apparent loudness of the overall mix without
diminishing the "power" behind the spikes.
Be Forewarned: With the
LIMITER engaged, you can
still overdrive the amplifier
into clipping. It just takes a
stronger signal to do it. So
even with the LIMITER turned on, you should
still pay attention to the OL LEDs

SUBWOOFER

Here's a special surprise: If you bought the
M•1200/M•1400 amplifier to power a subwoofer
system, you just saved yourself the cost of a
crossover! The M•1200/M•1400 amps have an
active SUBWOOFER filter built in. You can use
it, along with the variable LOW CUT FILTER
in a second M•1200/M•1400, to reproduce the
function of a crossover.
5
dB
0
dB
–5
dB
–10
dB
–15
dB
20 100 1k
Hz Hz Hz
Subwoofer Filter
1
CHANNEL
/ BRIDGE / MONO
INPUT
LOW CUT
FILTER
BALANCED
TYPICAL OR
35 Hz UNBALANCED
STAGE
MONITOR
100 Hz
OFF 170 Hz
CONSTANT DIRECTIVITY
HORN EQ /AIR EQ
4.5 k Hz
ON
2k Hz
5.6k Hz
AIR EQ AIR EQ OFF
TYPICAL
Since most low-frequency energy is mono-
phonic (the same in both channels), the
subwoofer circuit takes the signal from both
Channels 1 and 2 and sums them together. This
summed signal is then directed to both power
amplifier output stages. It doesn't matter
whether the AMP MODE
STEREO, MONO, or BRIDGE, it will sum the
inputs when the OUTPUT APPLICATION
switch is set to SUBWOOFER.
Here's how to configure it:
1. Turn the M•1200/M•1400's POWER
2. Set the OUTPUT APPLICATION
to SUBWOOFER.
3. Select a rolloff point, via the FREQUENCY
sub-harmonics on up to the audible bass
range. At "63Hz," you'll get just the lowest
.
frequencies, more to be felt than heard.
You'll probably want to try this switch both
ways.
4. Connect your cords and speaker cables as
usual (see "Quick Start"
MODE
BRIDGE, depending on your application.
(STEREO and MONO operate the same
with SUBWOOFER activated).
5. Turn the M•1200/M•1400's POWER on.
Woof!
If you want to use a second M•1200/M•1400
to reproduce the rest of the audio range, follow
this procedure:
1. Connect the THRU
subwoofer amplifier to the INPUT
on the second amplifier.
10k 20k
2. With POWER off, set the OUTPUT
Hz Hz
APPLICATION
amplifier to FULL RANGE (LIMITER either
ON or OFF).
AMP MODE
MONO
STEREO
TYPICAL
OUTPUT APPLICATION
FULL SUB
RANGE WOOFER
LIMITER
(CH1 & CH2)

FREQUENCY

STEREO
TYPICAL
ON OFF
THRU
switch is set to
switch: At "125Hz," you'll get the low
to either STEREO, MONO, or
jacks on the first
switch on the second
INPUT
BALANCED
OR
UNBALANCED
125Hz
ON
63Hz
OFF
TYPICAL
THRU
off.
switch
). Set the AMP
jacks
2
CHANNEL
LOW CUT
FILTER
TYPICAL
35 Hz
STAGE
MONITOR
100 Hz
OFF 170 Hz
CONSTANT DIRECTIVITY
HORN EQ /AIR EQ
4.5k Hz
2k Hz
5.6k Hz
AIR EQ AIR EQ
21