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Earthworks M23R Reference Omnidirectional Measurement Mic

23 kHz reference-grade omnidirectional small-diaphragm condenser measurement microphone

Product Description

The Earthworks M23R is an omnidirectional (pressure) microphone designed for measurement purposes. It utilizes a pre-polarized condenser capsule directly coupled to a wideband, low output impedance preamplifier. The M23R requires 24-48V phantom power at 10 mA. It features a linear frequency response from 3 Hz to 23 kHz, very low handling noise, uniform polar pattern, and high SPL handling capabilities. Its unique circuitry excludes the transconductance of the input FET from the overall gain structure. This means the sensitivity remains very stable when the microphone is subjected to variations in ambient temperature. The M23R meets or exceeds ANSI Type 1 requirements.

Each Reference Series measurement microphone is manufactured to within ±0.5 dB of each other in frequency response and sensitivity. This ensures that any microphone in the series will be matched to all others now and forever while also eliminating the necessity of ECFs (Electronic Calibration Files) in most cases. The M23R is delivered with its own calibration chart providing its individually measured open-circuit sensitivity and the frequency response curve. Should it be needed, an ECF containing the frequency response data for importing directly into measurement software is available from Earthworks upon request. A mounting clip and calibrator adapter are included with the microphone.


Earthworks M23R is ideally suited for acoustical measurements, sound system setup and troubleshooting, room acoustics, or any application where an accurate measurement microphone is required. The wide linear minimum-phase response and fast clean impulse response (Fig. 2) make the M23R especially suited for time domain measurements.

The M23R is simple to operate. Connect the microphone to a preamplifier supplying 24-48 V phantom power using a standard XLR microphone cable. Please allow up to one minute for the microphone to settle. Plugging in the microphone “hot” (phantom power already present at the input) will not damage the microphone. For optimum results it is recommended pointing M23R toward the sound source.

This microphone has no removable parts.


The microphone’s sensitivity at 1 kHz is measured at the factory. The sensitivity in mV/Pa is provided on the included calibration chart. If on-site calibration is required, use the included one-half inch standard calibrator adapter.

Product Specifications

Condition New
Length 6.3 in
Diameter 0.9 in
Unit Weight 0.35 lb
Tube or Solid State Solid State
Transducer Type Condenser
Polar Pattern Omni-Directional
Number of Microphones Single Microphone
Impedance 600 ohms
Frequency Range 3 Hz - 23 kHz
Sensitivity -29 dBV/Pa (36 mV)
Max. SPL 140 dB
Analog or Digital Analog

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