21
simply stops. This causes a sine wave to
“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 and cause
distortion. It just takes a
stronger signal to do it. So even with the
LIM-
ITER
turned on, you should still pay attention
to the
OL
LEDs .
SUBWOOFER
Here’s a special surprise: If you bought the
M•1400/M•1400i amplifier to power a
subwoofer system, you just saved yourself the
cost of a crossover! The M•1400/M•1400i amp
has an active
SUBWOOFER
filter built in. You
can use it, along with the variable
LOW CUT
FILTER
in a second M•1400/M•1400i, to re-
produce the function of a crossover.
20Hz 100Hz 1kHz 10kHz 20kHz
–15
dB
–10
dB
–5
dB
0dB
5
dB
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
switch is set to
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•1400/M•1400i’s
POWER
off.
2. Set the
OUTPUT APPLICATION
switch
to
SUBWOOFER
.
3. Select a rolloff point, via the
FREQUENCY
switch: At “125Hz,” you’ll get the low
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. Make sure the
LOW CUT FILTER
is set to
OFF
or nearly
OFF
. If it is turned up above
the subwoofer cutoff frequency, the output
from the amplifier will be greatly diminished.
5. Connect your cords and speaker cables as
usual (see “Quick Start” on page 4). Set
the
AMP MODE
to either
STEREO,
MONO,
or
BRIDGE
, depending on your
application. (
STEREO
and
MONO
operate
the same with
SUBWOOFER
activated).
6. Turn the M•1400/M•1400i’s
POWER
on.
Woof!
CHANNEL
2
1
CHANNEL
63Hz
125Hz
CONSTANT DIRECTIVITY
HORN EQ /AIR EQ
CONSTANT DIRECTIVITY
HORN EQ /AIR EQ
INPUT
THRUTHRU
INPUT
AMP MODE
FREQUENCY
4.5 k Hz
ON
6k Hz
2k Hz
MONO
(CHS SUMMED)
B
R
ID
G
E
LIMITER (CH1 & CH2)
OFF
FULL
RANGE
SUB
WOOFER
LOW CUT
FILTER
LOW CUT
FILTER
OUTPUT APPLICATION
BALANCED
OR
UNBALANCED
BALANCED
OR
UNBALANCED
ON
/ BRIDGE / MONO
170 Hz
OFF
4.5k Hz
6k Hz
2k Hz
170 Hz
100 Hz
OFF
STAGE
MONITOR
100 Hz
STAGE
MONITOR
OFF
TYPICAL
ON
OFF
TYPICAL
TYPICAL
35 Hz
TYPICAL
35 Hz
STEREO
TYPICAL
STEREO
TYPICAL
AIR EQ
AIR EQ
Subwoofer Filter
