Earthworks M30BX Users Manual

Electronic Calibration Files

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your ECF to the valid email address provided in
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M30BX

Battery Powered

Measurement Microphone

User’s Guide

Service & Repair

If you have any problems with your Earthworks
products, please contact our Service & Repair
Department.

Email: [e-mail]
Telephone: [phone], ext. 119

Printed in USA

MADE IN USA

earthworksaudio.com

July 11, 2018

M30BX

Description

The Earthworks M30BX is an omnidirectional (pressure)
microphone designed and calibrated for measurement
purposes. It is a pre-polarized condenser microphone
directly coupled to a wideband, low output impedance

preamplier. The M30BX requires a single type P28L
(Lithium) or equivalent 6V battery as a power source. It
features a linear free-eld frequency response from 9 Hz
to 30kHz (please see the enclosed individual calibration

chart). It has low handling noise and a uniform polar pat­tern. Its unique circuitry excludes the transconductance
of the input FET from the overall gain structure. The sen­sitivity remains very stable when the microphone is sub­jected to variations in ambient temperature. The M30BX
meets or exceeds ANSI Type 1 requirements.

Each microphone is delivered with its own calibration
chart providing its individually measured open-circuit
sensitivity and the frequency response curve. A computer
le containing the frequency response data for import­ing directly into measurement software is available from
Earthworks, Inc. upon registering your new microphone. A
mounting clip, a calibrator adapter, an XLR to RCA adapt­er, and a battery are included with the microphone.

Applications

The Earthworks M30BX is ideally suited for on-location
acoustic measurements including loudspeaker design
and quality control, sound system setup and trouble­shooting, room acoustics, or any application where an

accurate free-eld measurement microphone is required

and portability is important or a power source is not read­ily available. Many test systems manufacturers, such as

DRA Labs (MLSSA

™

), Smaart™ and DEQX™, recommend
M30BX microphones. The wide linear minimum-phase
response and fast, well-damped impulse response make
M30BX an excellent microphone for loudspeaker design,
especially for time domain measurements.

The M30BX is simple to operate. Make sure the battery
(included) is properly installed in the microphone. To open
the battery compartment hold the microphone by the up­per body and unscrew the battery cover sleeve (this cover
is not removable). The battery is only switched on when

an XLR connector is plugged into the microphone. The

M30BX will not operate from phantom power.

The M30BX will drive either balanced or unbalanced in­puts. An XLR to RCA adapter is enclosed for driving un­balanced inputs of sound cards directly. Please note that
the best S/N ratio is achieved using a balanced interface.

Calibration

The microphone is calibrated at the factory at 1 kHz (in­dependent of any frequency weighting). The sensitivity in

mV/Pa is provided on the enclosed calibration chart. If

on-site calibration is required, use the enclosed one-half
inch standard calibration adapter.

Specications

Frequency response: 9Hz to 30kHz +1/-3dB

Polar Pattern: Omnidirectional

Sensitivity: 3mV/Pa (Typical)
Power Requirements: 6V Battery Type P28
(2CR-1/N, 4LR44 or eq.)
Peak Acoustic Input: 140dB SPL
Output: XLR-3
Minimum Load: 600Ω between pins 2 & 3

Noise: 20dB, A equivalent

Dimensions L x D: 220 x 23 mm (8.65 x .910 in.)

Weight: 180g (.4lb)

Specications are subject to change without notice.

Pin 1
“Shield”

Pin 3
“-”

XLR Output Connector Assignment of M30BX

Frequency Response of M30BX (typical)

Impulse Response of M30BX (typical)

Pin 2
“+”

NOTE: Earthworks recommends re-calibration every

ve (5) years.

M30BX Open Battery Compartment

Polar Response of M30BX (typical)