Crest audio LH2 SPECIFICATIONS
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 LH
TM
2 is a newly designed non-traditional, three-way speaker
system comprised of one 15" high power woofer, one 15" high power midwoofer, and a 2" exit compression driver coupled to a 90° x 40° constant directivity 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 LH
TM
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 rectangular 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 cabinet. The trapezoidal shape resists the formation of standing waves by causing 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 LH
TM
2 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 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 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 protection circuit in both full-range and bi-amp modes of operation. When the high
frequency drive level to the LH
TM
2 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 component 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 attenuated (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
LH
TM
4
LHTM5M
LHTM6M
LH
TM
7M
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 limited (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 content of live music situations. High frequency test signals expose the speaker system
to synthesized tones that may extend
beyond audiobility. 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 determining how accurately a given unit reproduces an input signal. The frequency
response of the LH
TM
2 (Figure 1) is measured at a distance of 1 meter using a 1
Watt (into the nominal impedance) sweptsine 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 specifications 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
Amplitude Response (1W 1m On-Axis)
110
100
90
80
dB SPL (re 20 Pa)
70
20 50 100 200 500 1k 2k 5k 10k 20k
Figure 1
Lower Curve: Midrange Contour = Norm, Upper Curve: Midrange Contour = High
Frequency (Hz)
Impedance
100
50
30
20
Z
(
)
10
5
3
2
1
20 50 100 200 500 1k 2k 5k 10k 20k
Figure 2
Lower Curve: Midrange Contour = High, Upper Curve: Midrange Contour = Norm
Frequency (Hz)
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