HM-1 Self-Powered Loudspeaker System
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The Meyer Sound HM-1 is a very compact, full-range self-powered loudspeaker system designed to serve in a wide variety of installed sound reinforcement and repro-duction applications.
The HM-1 incorporates significant design innovations that afford unprecedented performance with practical advantages. In contrast to conventional small speaker systems, the cabinet venting is tuned at 40 Hz to provide flat, full-range response with half-space loading. The concentric tweeter mounting structure is optimized to minimize both back-wave interference and IM distortion. A constant-directivity high-frequency horn affords a 100° beam width, and sophisticated phase-correction circuitry assures true point-source performance without the off-axis cancellation effects that plague customary dual-concentric designs.
By implementing distributed amplification, the HM-1 affords substantial advantages in reliability and ease of installation when compared with constant-voltage (70 V) distributed systems. The HM-1 accepts a unipolar 48 VDC power source which may be supplied using twisted-pair wiring jacketed with the signal source conductors, eliminating the need for wiring conduits and greatly reducing induced noise. Its amplifier and signal-processing circuits are designed to tolerate supply voltage drops of up to 15%, accommodating light-gauge cables and long cable runs. Internal energy storage circuits minimize the system’s peak-to-average supply current demands, allowing efficient use of switched-mode regulated supplies.
The HM-1 is a two-way system comprising a 7" graphite cone low-frequency driver, and a concentrically-mounted 1" soft-dome high frequency driver with constant-directivity horn, in a vented cabinet. Integral bi-amplifiers affording 400 Watts total power output are built into the enclosure, along with an active crossover, driver protection voltage limiters, and frequency and phase response alignment circuitry. A laser-trimmed differential input stage affords superior common-mode rejection to accommodate simple twisted-pair signal distribution. Front-panel LEDs indicate power, signal limit, and thermal overload, and a rear-panel circuit breaker provides overall DC power protection.
The magnetically shielded HM-1 enclosure is coated with a textured black or white finish, and a variety of factory-installed mounting configurations may be ordered. Optional accessories include a remote switched-mode power supply, a variable-speed cooling fan assembly controlled from an integral rear-panel drive output, and an auxiliary subwoofer that provides flat response to 42 Hz in free field and is powered by the HM-1 low-frequency amplifier.
HM-1S Specifications
Click here for a graphic of the line drawings with dimension measurements included.You can also download this product data sheet in Adobe Acrobat format.
Acoustical 1 (each loudspeaker) |
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| Frequency Range 2 | 42 Hz to 20 KHz |
| Free Field | ±2.5 dB 100 Hz - 20 KHz; -6 dB 42 Hz - 100 Hz |
| Half Space3 | ±2.5 dB 90 Hz - 20 KHz; -3 dB 42 Hz - 90 Hz |
| Free Field with Subwoofer 4 | ±2.5 dB 42 Hz - 20 KHz |
| Phase Response 5 | ±20° 250 Hz - 15 kHz |
| Maximum SPL 6 | Without Sub: 116 dB SPL; With Sub: 120 dB SPL |
| Off-axis Amplitude Response | ±3.5 dB 100 Hz - 20 KHz up to 45° coverage 7 |
| Crossover | Complex roll-off shape, approx. 3 kHz acoustic amplitude |
| Signal to Noise Ratio | >100 dB (A-weighted noise floor to max SPL) |
Coverage |
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| (-6dB points) | 100°H 100°V |
Tranducers |
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| Dual-Concentric Drivers (magnetically shielded) | |
| Low Frequency | 7" graphite cone driver |
| High Frequency | 1" soft dome tweeter |
| Subwoofer (optional) | 10" cone driver (not shielded) |
Amplifiers |
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| Type | Complementary MOSFET output stages class A/B, bridged |
| Output Power | 400 Watts RMS, 200 Watts/channel at 4 ohms (with subwoofer) |
| THD, IM, TIM | <.02% |
Audio Input |
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| Connector | Options are 1 female XLR or a pluggable terminal strip |
| Type 8 | Differential balanced input circuit 8 |
| Impedance | 10 kohm differential (between pins 2 and 3) |
| XLR Wiring | Pin 1: chassis; Pin 2: + signal; Pin 3: - signal |
| RF Filter | Common Mode: 425 kHz low-pass; Differential Mode: 142 kHz low-pass |
| Common Mode Rejection Ratio | >80 dB (50 Hz - 1 kHz); typically 90 dB |
AC Power |
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| Voltage | Nominal: 48 VDC; Maximum: 52 VDC; Minimum: 35 VDC |
| Current 9 | Typical: 2.0 Arms, 3.5 Apk; Maximum in limiting: 3.0 Arms, 5.0 Apk |
Physical |
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| Dimensions | Height: 11.0"; Width: 8.4"; Depth: 9.7", 10.5" with fan attachment |
| Weight | 11.0 lb (5.0 kg); shipping: 13.5 lb (6.1 kg) |
| Protective Grill | Removable perforated steel grill causes <0.5dB response variation |
| Enclosure/Finish | All birch plywood/black textured |
Footnotes:
- Measurements are taken at 1 m on-axis, 1/3 octave, unless otherwise stated.
- Amplitude tolerance depends on loading conditions and whether the subwoofer is used.
- Flush-mounted into single boundary surface.
- Subwoofer adds approximately 8 dB 42 - 100 Hz.
- Phase variation from pure delay and minimum phase removed.
- Pink noise or music.
- A gradual amplitude attenuation occurs as the angle increases beyond 45°. Greater attenuation occurs at 2 kHz and beyond 10 kHz. There are no response peaks.
- Capacitively coupled; accepts up to ±50 VDC common mode.
- Idle current @0.4 A; using the slaved subwoofer increases stated currents by @20%.
