Application
The combination of the B-212CT bass reproducer
and the MR- 1 09CT lower midrange reproducer forms the
basis for a sound reinforcement stack that delivers extremely
high sound quality at high SPL. This combo, when
complemented by suitable high frequency transducers,
reproduces concert sound with exceptionally wide
dispersion and freedom from audible distortion.
Drivers are built to withstand continuous use at high
average power inputs without overheating. When operated
within the units' specifications, field failures are virtually
unknown, making it unnecessary to haul spares around on
location.
Cabinet design has been optimized to accommodate
the need for quick set-up and tear-down, minimum visual
blockage of the stage, and maximum usable life. Only the
highest quality materials and techniques are used in these
components, resulting in a product whose performance
could not be audibly improved irrespective of price.
Primary application is for multiple use in stacks for
indoor and outdoor concert sound reinforcement where it
is necessary to provide the maximum amount of sound from
a minimum of frontal area. These units have a high acoustical
output per unit of weight, and may be flown where sight line
requirements prevent a conventional stacking configuration.
Description of Lower Midrange
Unit
The MR- 1 09CT is a straight exponential horn with
a 20OHz cut-off frequency. The horn flare is constructed o f
hand-laminated fiberglass with high density sheets inserted to
damp resonances to well below cut-off. Additional damping
material is used inside the enclosure to reduce resonances,
even at 130dB SPL in the throat region.
The drive unit incorporates a large Alcomax magnet,
thermally bonded to a heatsink to improve heat dissipation,
minimize stray magnetic f ields and maximize the efficiency o f
return magnetic fields. This magnetic structure produces
12,000 Gauss on the 75mm. copper edgewound ribbon voice
coil.
The coil is bonded with high temperature adhesive
(similar to that used in automotive disc brakes) to an
aluminum former for maximum heat dissipation. All interior
surfaces are anodized black to absorb heat radiated by the
voice coil assembly. The frame is six-spoke, pressure cast
aluminum. Machined onto the drive unit is a precision integral
phase correcting plug to improve dispersion and high
frequency response.
The horn box is constructed of cross grain
laminated Baltic birch, and is equipped with metal corners,
skids, handles and a protective lid that clamps on with
recessed, spring-loaded twist catches. An internal passive
200Hz crossover is provided to protect the system from
inadvertent low frequency signals. Input connections are male
and female 15
amp twist-lock connectors, dual
1/4"
phone jacks and dual
banana plugs.
The MR-109CT lower midrange unit is specifically
designed to meet the demanding requirements of high level
sound reinforcement. The MR-109CT excels in both power
handling and distortion as compared to other competitive
compression driver/horn combinations. This new level o f
performance results in exceptional clarity and definition in
the principal music band. In addition, high frequency
distortion is reduced by allowing a higher crossover
frequency to the high
frequency drivers.
Specifications
Sensitivity at 1 watt
and 1 meter
107dB
Maximum SPL at
1 meter
128dB
Frequency response
±
3dB
200-1,60OHz
±
6dB
160-2,20OHz
Recommended
crossover frequencies
30OHz; 1,60OHz
Power handling capacity
150 watts continuous, test
tones
250 watts continuous, program
Distortion
Less than 4% at full power;
typically less than 1 %
Dispersion
100o H x 40o V
Impedance
Nominal 8 ohms
Minimum, 5.5 ohms
Finish
Semi-gloss, black catalyzed
polyurethane
Dimensions
151/2" H x 25" W x 28" D
Weight
82 lbs.
