Crest Audio LH7M LOUDSPEAKER User manual

SERIES
Features Description
• Smooth frequency response characteristics
• 500 watt continuous rated woofer
• 150 watt continuous rated compression driver
• 60 degree x 40 degree Constant Directivity horn with 2" throat
• High power crossover components
• Neutrik Speakon®connectors with automatic switching bi-amp input
• Dual-angle cabinet design
• Recessed steel handles with comfortable round hand-grip
• Stand adapter for side-fill use
• Heavy gauge metal grill with black powder-coat finish
• High-impact resistant polypropylene cabinet corners
• Rugged stand adapter
• Exterior grade 3/4" 7-ply all Poplar APA-1 plywood
• Scuff and weather resistant, black Hammer-Head™ finish
The Crest Audio LH™7M is a newly designed two-way stage monitor
comprised of two 12" high-power woofers, one 2" exit compression
driver coupled to a 60° x 40° constant directivity horn.
As with all LH™ full-range speakers, this unit can be driven in full-
range or bi-amp mode simply by plugging into the desired jack on the
input plate. The LH™7M cabinet has a dual-angle back for use in long
and short throw applications. This shape also greatly reduces the
build-up of internal standing waves. Standing waves are internal ampli-
tude peaks that occur due to reflections within the cabinet at frequen-
cies related to the internal dimensions of the cabinet. This ensures a
minimum of mid-bass and mid-range coloration of the reproduced
sound due standing waves within the cabinet. Additionally, a stand
mount adapter is included for easy side-fill applications.
The LH™7M is constructed of very high quality 3/4" 7-ply all-Poplar ply-
wood, which is void-free, medium density, and warp-resistant.The LH™7M
cabinet is finished with Crest Audio’s durable black Hammer-Head poly-
coating. Polymer corners are also added to provide further protection to the
cabinet. A black powder-coated heavy-gauge metal grill covers the entire
front of the monitor to protect the drivers from unforeseen impacts.
Crest Audio’s protection circuit for mid and high frequency driver pro-
tection is included as a standard feature. The input signal is routed
through the protection circuit in both full-range and bi-amp modes of
operation. When high frequency drive level to the LH™7M exceeds
predetermined thresholds, the protection circuit is temporarily
engaged. This subtly decreases the signal level applies to high fre-
quency driver so that it will not be damaged due to long term over-
powering. Short duration transients will not be attenuated by the pro-
tection circuit and thus have the potential to damage the driver. The
protection circuit is realized through the use of a dynamically resistive
component in conjunction with a switched padding circuit.
An additional feature of the crossover is the use of a new switching
Neutrik Speakon®connector for the bi-amp input. It is no longer nec-
essary to manually switch, or move jumpers to reconfigure the
crossover circuitry when bi-amping any of the LH series loudspeak-
ers. This connector is wired 1+, 1- for the woofer, with 1+ being posi-
tive, and 2+, 2- for the high frequency driver, with 2+ being positive.
As with the full range inputs, simply insert your Speakon bi-amp plug
into the bi-amp input connector, and twist clockwise 1/8 turn. This sim-
ple action switches out the crossover, and simultaneously connects
the woofer and driver directly to the bi-amp speaker cable.
LHTM7M
Loudspeaker
Full Range
Other LH series loudspeakers
LHTM7M
LHTM1
LHTM2
LHTM3
LHTM4
LHTM5M
LHTM6M
1,000W
600W
1,000W
500W
1,200W
400W
500W
2,000W
1,200W
2,000W
1,000W
2,400W
800W
1,000W
4,000W
2,400W
4,000W
2,000W
4,800W
1,600W
2,000W
Power Handling Continuous Program Peak

Specifications LHTM7M Loudspeaker
Power Handling
Crest Audio rates this unit’s system power
handling using a modified form of the AES
Standard 2-1984. Utilizing audio band lim-
ited (20 Hz - 20 kHz) pink noise with
peaks over four times the RMS level. This
strenuous test signal assures the user that
every portion of this system can withstand
high impact music. The test signal con-
tains large amounts of low frequency
energy, effectively simulating the frequen-
cy content of live music situations. High
frequency test signals expose the speaker
system to synthesized tones that may
extend beyond audibility. This rating is
contingent on having a minimum of 3 dB
of amplifier headroom available so as to
ensure that clipping does not occur.
Frequency Response
This measurement is useful in determin-
ing how accurately a given unit repro-
duces an input signal. The frequency
response of the LH™7M (Figure 1) is
measured at a distance of 1-meter using a
1 watt (into the nominal impedance)
swept-sine input signal.
20 50 100 200 500 1k 2k 5k 10k 20k
Frequency (Hz)
1
2
3
5
10
20
30
50
100
Impedance
Z
()
Figure 2
20 50 100 200 500 1k 2k 5k 10k 20k
Frequency (Hz)
70
80
90
100
110
dB SPL (re 20 Pa)
Amplitude Response (1W 1m On-Axis)
Figure 1

Specifications LHTM7M Loudspeaker
frequency response
usable low frequency limit (-10 dB point)
power handling
sound pressure level
maximum sound pressure level (1 meter)
radiation angle measured
transducer complement
box tuning frequency
crossover frequency (internal passive)
recommended minimum active crossover
time offset
impedance Z
input connections
enclosure materials and finish
dimensions (H x W x D)
net weight
LHTM7M Loudspeaker
58 Hz to 20 kHz (±3 dB)
47 Hz
Full Range: 1,000 W continuous 89.4 V RMS 2,000 W program 4,000 W peak
passive high freq:150 W continuous 34.6 V RMS 300 W program 600 W peak
Full Range 97.0 dB SPL, (2.83 V input)
high freq107 dB SPL, (2.83 V input)
Full Range 126.8 dB SPL continuous 132.8 dB SPL peak
High Freq 134.5 dB SPL continuous 140.5 dB SPL peak
90 degrees horizontal x 40 degrees vertical
Low Freq 1x 15" Woofer, vented basket
High Freq 2.0" Exit / 75 mm voice coil compression driver on a CD horn
Fbox 56 Hz
Low Freq High Freq - 1700 Hz
Low Freq High Freq - 1500 Hz at 12 dB/octave
Low Freq 0.00 ms
High Freq 0.60 ms
Full Range Nominal 8.0ΩMinimum 7.1Ω
High Freq Nominal 8.0ΩMinimum 6.8Ω
2x Neutrik Speakon
4 conductor input jacks
1x Neutrik Speakon 4
conductor biamp switching input jack
3/4" 7-ply premium, exterior grade, all-poplar, void-free plywood. Material conforms
to APA-1 specification. Finished in black, Hammer-Head poly-coating.
front 30.5" x 219.0" x 17.0" 775 mm x 483 mm x 445 mm
97 Lbs. (44.1 kg)
Architects’ & Engineers’ Specifications:
The loudspeaker system shall have an operat-
ing bandwidth of 59 Hz to 20 kHz. The nominal
output level shall be 97.0 dB when measured
at a distance of one meter with an input of one
watt. The nominal impedance shall be 8.0
ohms. The maximum continuous power han-
dling shall be 500 watts, maximum program
power of 1,000 watts and a peak power input
of at least 2,000 watts, with a minimum ampli-
fier headroom of 3 dB.
The nominal radiation geometry shall be 60
degrees in the horizontal plane and 40 degrees
in the vertical plane. The outside dimensions
shall be 30.5 inches high by 19.0 inches wide by
17.0 inches deep. The weight shall be 97
pounds. The loudspeaker system shall be a
Crest Audio model LH™7M.

Crest Audio Inc.
16-00 Pollitt Dr. Fair Lawn, NJ 07410
TEL: [phone] FAX: [phone]
www.crestaudio.com
*80304812*
Crest Audio reserves the right to make improvements in manufacturing or design which may affect specifications.
8/22/01
v.1.5