Transcript
LH 3 Loudspeaker TM
Power Handling
SERIES
Continuous
Program
Peak
500W
1,000W
2,000W
1,200W 2,000W 2,400W 800W 1,000W 2,000W
2,400W 4,000W 4,800W 1,600W 2,000W 4,000W
Full Range
LHTM3
Other LH series loudspeakers
LHTM1 LHTM2 LHTM4 LHTM5M LHTM6M LHTM7M
Features • 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
600W 1,000W 1,200W 400W 500W 1,000W
Description The Crest Audio LHTM3 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 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 LHTM3 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.
• 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 LHTM3 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.
Specifications
TM
LH 3 Loudspeaker
Power Handling
Amplitude Response (1W 1m On-Axis)
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 21984. 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
dB SPL (re 20 Pa)
110 100 90 80 70 20
Figure 1
50
100
200
500 1k Frequency (Hz)
2k
5k
10k
20k
Lower Curve: Midrange Contour = Norm, Upper Curve: Midrange Contour = High
Impedance 100 50 30 Z 20 ( ) 10 5 3 2
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.
1 20
Figure 2
50
100
200
500 1k Frequency (Hz)
2k
5k
10k
20k
Lower Curve: Midrange Contour = High, Upper Curve: Midrange Contour = Norm
Beamwidth
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.
Beamwidth (Degrees)
360 300 180 140 100 80 60 40 30 20
Horizontal Vertical 50
100
200
Figure 3
500 1k Frequency (Hz)
2k
5k
10k
20k
Q & Directivity Index 20
100
Q
Di 10
10
1 20
Figure 4
50
100
200
500 1k Frequency (Hz)
2k
5k
10k
0 20k
Specifications
TM
LH 3 Loudspeaker
Horizontal Polars 0
o
o
0 o
30
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o
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o
-90
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o o
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-60
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-90
2000 Hertz
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-90
4000 Hertz
o
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60
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90
o
-60
o
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60
o
90
-30
-90
8000 Hertz
-60
o
90
-90
16000 Hertz
Vertical Polars o
90
90 60
o
o
90 60
30
o
30
o
125 Hertz
-60 -90
90
-30
250 Hertz
o
-60 -90
500 Hertz
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-60 -90
1000 Hertz
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8000 Hertz
-60 -90
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90 60
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4000 Hertz
-30
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2000 Hertz
30
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-30
60
0
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90 o
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0
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0 o
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-60
-90
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90
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90
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-30
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-60
1000 Hertz
0 o
30
o
60
o
-90
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o
-30
o
500 Hertz
0
o
30
-30
60
-60
90
250 Hertz
o
30
o
60
-90
o
-30
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-60
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0 o
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90
125 Hertz
o
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-30
60
-60
90
0 o
30
o
60
o
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-30
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o
-30
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16000 Hertz
-60 -90
o
o
o
o
Specifications
TM
LH 3 Loudspeaker LHTM3 Loudspeaker
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):
Passive MF/HF: High Frequency:
Input Connections: Enclosure Materials & Finish: Dimensions (H x W x D): Net Weight: Architects’ & Engineers’ Specifications: The loudspeaker system shall have an operating bandwidth of 53 Hz to 20 kHz. The nominal output level shall be 97 dB when measured at a distance of one meter with an input of one Watt. The nominal impedance shall be 8.0
53 Hz to 20 kHz (±3 dB) 40 Hz Full Range: 500 W continuous (63.2 V RMS) 1,000 W program 2,000 W peak 150 W continuous (34.6 V RMS) 300 W program 600 W peak
Full Range: 97.0 dB SPL, (2.83 V input) 104 dB SPL, (2.83 V input) Full Range: 126.8 dB SPL continuous 132.8 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 8 in. mid-range 2.0 in. exit / 75 mm voice coil compression driver on a CD horn Fbox: 36 Hz Low Frequency - Mid Frequency: 500 Hz Mid Frequency - High Frequency: 3,700 Hz
500 Hz at 18 dB/octave Low Frequency: 0.00 ms Mid Frequency: -0.30 ms High Frequency: 0.60 ms Full Range: Nominal: 8.0 Ω Minimum: 6.4 Ω Nominal: 8.0 Ω Minimum: 8.9 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: 33.5 in. x 22.38 in. x 19.75 in. 851 mm x 568 mm x 502 mm Rear: 33.5 in. x 12.75 in. x 19.75 in. 851 mm x 324 mm x 502 mm 120 Lbs. (54.4 kg)
Ohms. The maximum continuous power handling 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 amplifier 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 33.5 inches high by 22.38 inches wide by 19.75 inches deep. The weight shall be 120 pounds. The loud-speaker system shall be a Crest Audio model LHTM3.
Crest Audio reserves the right to make improvements in manufacturing or design which may affect specifications.
8/22/01 v.1.5
*80304808*
Crest Audio Inc. 16-00 Pollitt Dr. Fair Lawn, NJ 07410 TEL: 201.909.8700 FAX: 201.909.8744 www.crestaudio.com
