Larson Davis PRM831 is a microphone preamplifier for use with electret microphones with a Larson Davis Model 831 Sound Level Meter. The preamplifier requires very little supply current and operates over wide temperature and humidity ranges. The attenuation
is minimal when operating with 50 mV/Pa sensitivity microphones up to a Sound Pressure Level of 143 dB peak. The preamplifier will drive 300 feet of cable with an 20 kHz to a maximum amplitude of 10 V RMS.
Specifications
| GENERAL |
|---|
| Function | Specification | Remarks |
| Frequency | Response 5 Hz to 126 kHz | (+ 0.1 / -0.5) dB |
| Low-frequency response (high pass) | < 1.5 Hz | -3 dB |
| Attenuation | < 0.1 dB | Typical |
| Input Impedance | 10 GΩ // 0.16 pF | Typical |
| Output Impedance | 50 Ω | Typical |
| Maximum Output Voltage | 28 Vpp | 143 dB peak for microphones with 50 mV/Pa sensitivity |
| Maximum Output Current | 12 mA peak | |
| Distortion | Harmonics < -70 dBc | 8 V RMS Output @ 1 kHz |
| Output Slew Rate | 2 V/µs | Typical |
| Electronic Noise | 1.8 µV A-weighted
4.3 µV Flat (5.0 µV max) | Typical for 12 pF microphone |
| Power Supply Voltage | 15 V to 36 V | |
| DC Output Level | 0.5 X Power Supply Voltage | |
| Power Supply Current | 1.9 mA | Typical |
| Temperature Sensitivity | < ± 0.05 dB
-40 °F to 176 °F (-40 °C to 80 °C) | |
| Humidity Sensitivity | ±0.05 dB (0% to 99% RH) | Non-condensing |
| Dimensions | 0.5″ dia x 2.88″ L
(12.7 mm dia x 73 mm L) | |
| Compatibility | Larson Davis 377B02 or any ½″ electret microphones | ADP043 or ADP008A adaptors for ¼″ or 1″ microphones |
| ENVIRONMENTAL |
|---|
| Operating Temperature | -40 °F to 158 °F (-40 °C to 70 °C) |
| Operating Humidity | 0% to 99% RH Non-condensing |
| Temperature Sensitivity | ±0.005 dB/°C |
| Temperature Sensitivity with Model 377B02 microphone at 1 kHz |
| -40 °F to 14 °F (-40 °C to -10 °C) | < ± 1.0 dB |
| 14 °F to 122 °F (-10 °C to 50 °C) | < ± 0.5 dB |
| 122 °F to 158 °F (50 °C to 70 °C) | < ± 0.9 dB |
| Humidity Sensitivity with Model 377B02 microphone |
| 0% to 100% RH | < ± 0.5 dB |
| ACOUSTICAL FREQUENCY RESPONSE LIMITS |
|---|
| Frequency (Hz) | 0 degree Free-field | 90 degree Free-field | Random |
| 10.0 | 3.0 | -4.0 | 3.0 | -4.0 | 3.0 | -4.0 |
| 12.5 | 2.5 | -3.5 | 2.5 | -3.5 | 2.5 | -3.5 |
| 16.0 | 2.0 | -3.0 | 2.0 | -3.0 | 2.0 | -3.0 |
| 20.0 | 2.0 | -2.0 | 2.0 | -2.0 | 2.0 | -2.0 |
| 25.0 | 2.0 | -1.5 | 2.0 | -1.5 | 2.0 | -1.5 |
| 31.5 | 1.5 | -1.5 | 1.5 | -1.5 | 1.5 | -1.5 |
| 40 to 4000 | 1.0 | -1.0 | 1.0 | -1.0 | 1.0 | -1.0 |
| 5000 | 1.5 | -1.5 | 1.5 | -1.5 | 1.5 | -1.5 |
| 6300 | 1.5 | -2.0 | 1.5 | -2.0 | 1.5 | -2.0 |
| 8000 | 1.5 | -2.5 | 1.5 | -2.5 | 1.5 | -2.5 |
| 10000 | 2.0 | -3.0 | 2.0 | -3.0 | 2.0 | -3.0 |
| 12500 | 2.0 | -5.0 | 2.0 | -5.0 | 2.0 | -5.0 |
| 16000 | 2.5 | -16.0 | 2.5 | -16.0 | 2.5 | -16.0 |
| 20000 | 3.0 | -∞ | 3.0 | -∞ | 3.0 | -∞ |
| | with respect to level at 250 Hz (dB) |
| PHYSICAL |
|---|
| Microphone Thread | 11.7 mm – 60 UNS (.4606 – UNS) |
| Venting | Bottom of preamplifier by conneector |
| Output Connector | Switchcraft TA5M (5 pin male) |
| COMPLIANCE |
|---|
| IEC 61672-1 (2013) Class 1 and ANSI S1.40-2006 with Model 831C |
| IEC 61326-1 (2020) EMC requirements for electrical equipment |
| IEC 61010-1 (2010) Safety |
| ACCESSORIES |
|---|
| EPS2116 | Environmental protection shroud |
| CBLXXX | Extension cable for microphone and preamp. Available in lengths up to 200 ft. |
| CAL200 | Acoustic calibrator |
| 831C | Class 1 sound level meter |
| ORDERING INFORMATION |
|---|
| PRM831 | PRM831 Preamplifier and calibration check |
| PRM831-FF | PRM831 Preamplifier with 377B02 microphone and calibration check |
| PRM831-RI | PRM831 Preamplifier with 377C20 microphone and calibration check |
| CER-PREAMP | Factory calibration and certification for PRM831 |
