Cd Frequency; Amp Mode - Mackie M1200/M1400 Owner's Manual

CD Frequency

Your compression drivers' spec sheet should
have a suggested frequency for compensation
boost. If so, just turn the CONSTANT DIREC-
TIVITY switch ON and set its knob to match
that frequency. If your spec sheet doesn't have
that information, you can simply adjust the
Frequency knob by ear, preferably using the
same music as the actual performance (3.5kHz
is a good place to start).
15
dB
10
dB
5
dB
0
dB
–5
dB
20 100 1k
Hz Hz
Constant Directivity EQ
Wait, there's more: If you don't have con-
stant directivity horns, you can forget all this,
and leave the switch OFF.
Or, better yet, you can use this CONSTANT
DIRECTIVITY feature to enhance your EQ
curve. By setting the Frequency knob fully
clockwise, you introduce a very high frequency
boost to the signal (above 6kHz). And in
Mackie-land, this gentle boost has a name: AIR,
as seen on our SR series of consoles. By boost-
ing these high frequencies, AIR will breathe
life into your mix, making cymbals brighter
and vocals silkier.
Speaking of Mackie SR consoles: If you use
both the AIR feature on an SR console as well
as the AIR feature just described on the
M•1200/M•1400, you may be overdoing it. You
won't hyperventilate or anything, but it might
cause your audience to experience ear fatigue
from too much high-frequency content. Too
much of a good thing, perhaps.
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 OFF
AIR EQ
TYPICAL
More on Constant Directivity Horns
tended to beam straight ahead, so if you moved
away from front and center (off-axis), the bril-
liance and sizzle quickly diminished to a
muffled blur. Constant Directivity horns were
designed to spread the higher frequencies
evenly throughout the horn's dispersion pattern.
opening to the horn, using straight sidewalls in
both the horizontal and vertical planes (radial
10k 20k
horns typically have curved vertical sections
Hz Hz Hz
that cause beaming), and providing a flare at
the mouth of the horn to disperse the mid to
high frequencies.
an inherent roll-off of about 6 dB per octave
above about 3kHz. The exact frequency at
which the roll-off occurs (called the mass
breakpoint) depends on the materials used,
the mass of the moving parts (diaphragm and
voice coil) and the strength of the magnet. The
CONSTANT DIRECTIVITY HORN EQ control
on the M•1200/M•1400 compensates for this
natural roll-off in the power response of the
compression driver coupled to a CD horn, with
the end result of flat-frequency response (con-
stant) with a wide coverage angle (directivity).
PUT APPLICATION's
determines what kind of amplifier you want
the M•1200/M•1400 to be.

AMP MODE

MONO
STEREO
TYPICAL
OUTPUT APPLICATION
FULL
RANGE WOOFER
LIMITER
(CH1 & CH2)
STEREO
TYPICAL
ON OFF
THRU
Back in the early '70s, radial
horns were the common
mechanism for reproducing
high frequencies. Radial
horns had a serious problem,
though. The high frequencies
This was accomplished by using a smaller
All high-frequency compression drivers have
AMP MODE
This three-way switch, along with the OUT-
three-way switch,
INPUT
BALANCED
UNBALANCED
SUB
FREQUENCY
125Hz
63Hz
THRU
2
CHANNEL
LOW CUT
FILTER
TYPICAL
OR
35 Hz
STAGE
MONITOR
100 Hz
OFF 170 Hz
CONSTANT DIRECTIVITY
HORN EQ /AIR EQ
4.5k Hz
ON
2k Hz 5.6k Hz
OFF AIR EQ AIR EQ
TYPICAL
19