Crest Audio LH1 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
• 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 LHTM1 is a two-way speaker system comprised of one 15"
high power woofer, one 2" exit compression driver coupled to a 90° x 40° con-
stant directivity horn.
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
LHTM1 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 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.
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 high fre-
quency drive level to the LHTM1 exceeds predetermined thresholds, the pro-
tection circuit is temporarily engaged. This subtly decreases the signal level
applied to the high frequency driver so that it will not be damaged due to long-
term overpowering. Large amplitude, short duration transients will not be
attenuated by the protection circuit and thus have the potential to damage the
driver. The protection circuit is realized through the use of a dynamically resis-
tive 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 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.
LHTM1
Loudspeaker
LHTM1
LHTM2
LHTM3
LHTM4
LHTM5M
LHTM6M
LHTM7M
600W
1,000W
500W
1,200W
400W
500W
1,000W
1,200W
2,000W
1,000W
2,400W
800W
1,000W
2,000W
2,400W
4,000W
2,000W
4,800W
1,600W
2,000W
4,000W
Power Handling Continuous Program Peak

Specifications LHTM1 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 very 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 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 LH1 (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 LHTM1 Loudspeaker
Horizontal Polars
Vertical Polars
-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

Specifications LHTM1 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
LHTM1 Loudspeaker
48 Hz to 20 kHz ±3 dB
35 Hz
Full Range 600 W - 69.3 V RMS 1,200 W program 2,400 W peak
passive high freq 150 W - 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 44 Hz
Low Freq High Freq - 1600 Hz
Low Freq High Freq - 1600 Hz
Low Freq 0.00 ms
High Freq 0.60 ms
Full Range Nominal 8.0ΩMinimum - 6.9Ω
High Freq Nominal 8.0ΩMinimum - 8.2Ω
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 33.50" x 22.38" x 19.75" 851 mm x 568 mm x 502 mm
rear 33.50" x 12.75" x 19.75" 851 mm x 324 mm x 502 mm
106 Lbs. (48.2 kg)
Crest Audio Inc.
16-00 Pollitt Dr. Fair Lawn, NJ 07410 USA
TEL: [phone] FAX: [phone]
www.crestaudio.com
*80304806*
Crest Audio reserves the right to make improvements in manufacturing or design which may affect specifications.
8/21/01
v.1.5
Architects’ & Engineers’ Specifications:
The loudspeaker system shall have an operat-
ing bandwidth of 48 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 600 Watts, maximum program
power of 1,200 Watts and a peak power input
of at least 2,400 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 33.50 inches high by 22.38 inches wide
by 19.75 inches deep. The weight shall be 106
pounds. The loudspeaker system shall be a
Crest Audio model LHTM1.