Crest Audio LH2 LOUDSPEAKER User manual

Full Range
Other LH series loudspeakers
SERIES
Features Description
• Smooth frequency response characteristics
• 600 Watt continuous rated woofer
• 150 Watt continuous rated compression driver
• 90 degree x 40 degree constant directivity horn with 2" throat
• High power crossover components
• Neutrik Speakon®input connectors, with automatic biamp switching
• 15 degree trapezoidal cabinet design
• Recessed steel handles with comfortable round handgrip
• Heavy gauge metal grill with black, powder-coat finish
• Exterior grade 3/4", 7-ply all poplar APA-1 plywood
• Scuff and weather resistant, black Hammer-Head™ finish
The Crest Audio LHTM2 is a newly designed non-traditional, three-way speaker
system comprised of one 15" high power woofer, one 15" high power mid-
woofer, and a 2" exit compression driver coupled to a 90° x 40° constant direc-
tivity horn. The crossover in the LH2 is unique in that it allows both 15" woofers
to be operating in parallel below 300 Hertz. The mid-range is covered by the
upper 15" woofer up to the crossover of 1,700 Hertz to the compression driver.
As with all LHTM full-range speakers, this unit can be driven in full-range or
biamp mode simply by plugging into the desired jack on the input plate. The
LHTM2 has a trapezoidal shaped cabinet, rather than the more traditional rec-
tangular shape.This allows cabinet arrays to be constructed more easily. This
shape also greatly reduces the build-up of internal standing waves. Standing
waves are internal amplitude peaks that occur due to reflections within the
cabinet at frequencies related to the internal square dimensions of the cabi-
net. The trapezoidal shape resists the formation of standing waves by caus-
ing the internal reflections to cancel rather than reinforce each other. This
ensures a minimum of mid-bass and mid-range coloration of the reproduced
sound due to standing waves within the cabinet.
The LHTM2 is constructed of very high quality 3/4", 7-ply all-poplar plywood,
which is void-free, medium density and warp-resistant. The LHTM2 cabinet is fin-
ished with Crest Audio’s durable black Hammer-Head™ poly-coating. Polymer
corners are also added to provide further protection to the cabinet. A black, pow-
der-coated, heavy-gauge metal grill covers the lower section of the front of the
cabinet to protect the low and mid frequency drivers from unforeseen impacts.
Crest Audio’s protection circuit for mid and high frequency driver protection is
included as a standard feature. The input signal is routed through the protec-
tion circuit in both full-range and bi-amp modes of operation. When the high
frequency drive level to the LHTM2 exceeds predetermined thresholds, the
protection circuit is temporarily engaged. This subtly decreases the signal
level applied to the high frequency driver so that they will not be damaged due
to long term overpowering. Short duration transients will not be attenuated by
the protection circuit and thus have the potential to damage the drivers. The
protection circuit is realized through the use of a dynamically resistive com-
ponent in conjunction with a switched padding circuit.
An additional feature in the crossover circuitry is a mid-range contour switch.
This switch allows a choice between flat (HIGH position) and mildly attenuat-
ed (NORMAL position) mid-range frequencies. The position of this switch is
purely dependent on venue and personal sonic taste. As a suggestion, the
NORMAL position is more suitable for live (highly reflective, long reverb time)
venues. Whereas, the HIGH position is more suitable in venues where the
reverb time is relatively short.This switch is located on the rear panel input plate
and is actuated with a suitable tool such as a flat screwdriver tip, or door key.
LHTM2
Loudspeaker
LHTM2
LHTM1
LHTM3
LHTM4
LHTM5M
LHTM6M
LHTM7M
1,000W
600W
500W
1,200W
400W
500W
1,000W
2,000W
1,200W
1,000W
2,400W
800W
1,000W
2,000W
4,000W
2,400W
2,000W
4,800W
1,600W
2,000W
4,000W
Power Handling Continuous Program Peak

Specifications LHTM2 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 inpact music. The test signal contains
large amounts of low frequency energy,
effectively simulating the frequency con-
tent of live music situations. High frequen-
cy test signals expose the speaker system
to synthesized tones that may extend
beyond audiobility. This rating is contin-
gent 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 LHTM2 (Figure 1) is meas-
ured at a distance of 1 meter using a 1
Watt (into the nominal impedance) swept-
sine input signal.
Directivity
Beamwidth is derived from the -6 dB
points from the polar plots which are
measured in a whole space anechoic
environment. Q and Directivity Index
(Figures 3 & 4) are plotted for the on-axis
measurement position. These are specifi-
cations that provide a reference to the
coverage characteristics of the unit. These
parameters provide insight for proper
placement and installation in the chosen
environment.
20 50 100 200 500 1k 2k 5k 10k 20k
Frequency (Hz)
1
10
100
Q & Directivity Index
Q
Figure 4
20
10
Di
0
20 50 100 200 500 1k 2k 5k 10k 20k
Frequency (Hz)
30
40
60
80
100
140
180
300
360
Beamwidth (Degrees)
Beamwidth
Vertical
Horizontal
Figure 3
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 Lower Curve: Midrange Contour = High, Upper Curve: Midrange Contour = Norm
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 Lower Curve: Midrange Contour = Norm, Upper Curve: Midrange Contour = High

Specifications LHTM2 Loudspeaker
-90o
-60o
-30o
0o
30o
60o
90o
125 Hertz
-90o
-60o
-30o
0o
30o
60o
90o
250 Hertz
-90o
-60o
-30o
0o
30o
60o
90o
500 Hertz
-90o
-60o
-30o
0o
30o
60o
90o
1000 Hertz
-90o
-60o
-30o
0o
30o
60o
90o
2000 Hertz
-90o
-60o
-30o
0o
30o
60o
90o
4000 Hertz
-90o
-60o
-30o
0o
30o
60o
90o
8000 Hertz
-90o
-60o
-30o
0o
30o
60o
90o
16000 Hertz
0o
30o
60o
90o
-30o
-60o
-90o
125 Hertz
0o
30o
60o
90o
-30o
-60o
-90o
250 Hertz
0o
30o
60o
90o
-30o
-60o
-90o
500 Hertz
0o
30o
60o
90o
-30o
-60o
-90o
1000 Hertz
0o
30o
60o
90o
-30o
-60o
-90o
2000 Hertz
0o
30o
60o
90o
-30o
-60o
-90o
4000 Hertz
0o
30o
60o
90o
-30o
-60o
-90o
8000 Hertz
0o
30o
60o
90o
-30o
-60o
-90o
16000 Hertz
Horizontal Polars
Vertical Polars

Specifications LHTM2 Loudspeaker
Crest Audio Inc.
16-00 Pollitt Dr., Fair Lawn, NJ 07410 USA
TEL: [phone] FAX: [phone]
www.crestaudio.com
*80304807*
Crest Audio reserves the right to make improvements in manufacturing or design which may affect specifications.
8/22/01
v.1.5
Frequency Response, 1 meter on-axis,
swept-sine in anechoic environment:
Usable Low Frequency Limit (-10 dB point):
Power Handling:
Passive High Frequency Section:
Sound Pressure Level, 1 Watt, 1 meter in
anechoic environment:
Mid / High Frequency Section:
Maximum Sound Pressure Level (1 meter):
Mid / High Frequency Section:
Radiation Angle measured at -6 dB point
of polar response:
Transducer Complement
Low Frequency Section:
Mid Frequency Section:
High Frequency Section:
Box Tuning Frequency:
Crossover Frequency (internal passive):
Recommended Active Crossover
Frequency Region and Slope
Mid Frequency - High Frequency:
Time Offset:
Impedance (Z):
High Frequency:
Input Connections:
Enclosure Materials & Finish:
Dimensions (H x W x D):
Net Weight:
LHTM2 Loudspeaker
55 Hz to 20 kHz (±3 dB)
42 Hz
Full Range:
1,000 W continuous (63.2 V RMS)
2,000 W program
4,000 W peak
150 W continuous (34.6 V RMS)
300 W program
600 W peak
Full Range:
100.0 dB SPL, (2.83 V input)
104 dB SPL, (2.83 V input)
Full Range:
129.8 dB SPL continuous
135.8 dB SPL peak
134.5 dB SPL continuous
140.5 dB SPL peak
90 degrees horizontal x 40 degrees vertical.
1x 15 in. woofer, vented basket
1x 15 in. mid-woofer, vented basket
2.0 in. exit / 75 mm voice coil compression driver on a CD horn
Fbox: 45 Hz
Low Frequency - Mid Frequency: 300 Hz
Mid Frequency - High Frequency: 1,700 Hz
1,700 Hz at 18 dB/octave
Low Frequency: 0.00 ms
Mid Frequency: 0.00 ms
High Frequency: 0.60 ms
Full Range:
Nominal: 4.0 Ω
Minimum: 4.6 Ω
Nominal: 8.0 Ω
Minimum: 6.9 Ω
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: 49.0 in. x 22.38 in. x 19.75 in. (1,244 mm x 568 mm x 502 mm)
Rear: 49.0 in. x 12.75 in. x 19.75 in. (1,244 mm x 324 mm x 502 mm)
132 Lbs. (60.0 kg)
Architects’ & Engineers’ Specifications:
The loudspeaker system shall have an operat-
ing bandwidth of 55 Hz to 20 kHz. The nominal
output level shall be 100 dB when measured at
a distance of one meter with an input of one
Watt. The nominal impedance shall be 4.0
Ohms. The maximum continuous power han-
dling shall be 1,000 Watts, maximum program
power of 2,000 Watts and a peak power input
of at least 4,000 Watts, with a minimum ampli-
fier headroom of 3 dB.
The nominal radiation geometry shall be 90
degrees in the horizontal plane and 40 degrees
in the vertical plane. The outside dimensions
shall be 49 inches high by 22.38 inches wide by
19.75 inches deep. The weight shall be 132
pounds. The loud-speaker system shall be a
Crest Audio model LHTM2.