Crest audio LH3 SPECIFICATIONS
Full Range
Other LH series loudspeakers
SERIES
Features
Description
• Smooth frequency response characteristics
• 500 Watt continuous rated woofer
• 140 Watt continuous rated mid-range 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
• 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
TM
3 is a newly designed, three-way speaker system comprised of one 15" high-power woofer, one 8" heavy-duty mid-range, and a 2"
exit compression driver coupled to a 90° x 40° constant directivity horn.
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
LH
TM
3 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
3 is constructed of very high quality 3/4", 7-ply all-poplar plywood,
which is void-free, medium density and warp-resistant.The LHTM3 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 mid
and/or high frequency drive level to the LH3 exceeds predetermined thresholds, the protection circuit is temporarily engaged. This subtly decreases the
signal level applied to the mid and/or high frequency drivers 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.
LHTM3
Loudspeaker
LHTM3
LHTM1
LHTM2
LH
TM
4
LHTM5M
LHTM6M
LH
TM
7M
500W
600W
1,000W
1,200W
400W
500W
1,000W
1,000W
1,200W
2,000W
2,400W
800W
1,000W
2,000W
2,000W
2,400W
4,000W
4,800W
1,600W
2,000W
4,000W
Power Handling Continuous Program Peak
Specifications
LHTM3 Loudspeaker
Power Handling
There are many different approaches to
power handling ratings. 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 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 determining how accurately a given unit reproduces an input signal. The frequency
response of the LH3 (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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