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Zaxcom ZMT4 Miniature Transmitter


The ZMT4 can be ordered in one of two configurations:

ZMT4.5 - covering blocks 20 through 23 (512-608 MHz)

ZMT4.6 - covering blocks 23 through 26 (578 – 698 MHz)

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Design Matters

The ZMT4 has taken digital recording wireless to the next level with 30% better power consumption, NeverClip in all modes, power for all microphones - from a 5V lavalier to a 48V phantom powered mic, and a new ultra-low noise preamp.

Deliver pristine audio quality with Zaxcom's ZMT4, an incredibly small, lightweight, talent-friendly transmitter ideal for sound professionals. Weighing only 62g, the ZMT4 is constructed from a high-strength, impact-resistant nylon polymer casing with rounded edges and machined metal that's cool to the touch.

Microphone Connectivity

The ZMT4 has a wide range of power to cover nearly any professional analog microphone - 5V lavalier mics as well as condenser, balanced dynamic, or ribbon microphones running at 12, 24, 36 or 48V.

Perfect for boom pole operation, the ZMT4 can be positioned at the top of a boom pole directly behind the microphone instead of near the bottom. By removing the internal or external cable, operators can eliminate cable noise that can affect the audio track. Boom microphone connectivity is via a 3-pin balanced LEMO.

Encrypted Audio

The ZMT4 transmits using 100% digital modulation allowing audio to be fully encrypted. Digital encryption is the only way to keep all audio transmission private. A digital transmission also provides audio quality superior to analog systems.

Adaptive Antenna Optimisation

This new feature in the ZMT4 improves radiation of the bodypack’s antenna when it’s placed in contact or near the human body. Normally, putting a bodypack on talent decreases transmission range because the body absorbs some of the signal. With adaptive antenna optimisation, the external antenna is actively matched to its condition to optimise radiation and minimise distortion, keeping the signal at its best.

Microphone Preamp

The ZMT4 features an all-new preamp design. The noise content of the preamp and A-D combination now utilises NeverClip with both lav and balanced boom mics, making the environment and self-noise of the microphone the dominant noise components.


NeverClip is available in all modes on the ZMT4. It works by utilising two A-D converters to extend the dynamic range of the transmitter to 136 dB, so there’s never any limiter distortion.

Internal Recording

Audio is simultaneously transmitted and recorded to a removable microSD card using the highly reliable MARF (Mobile Audio Recording Format) which eliminates file corruption common to recordings due to a dead battery or early card removal.


ZMT4 is equipped with ZaxNet, a long-range remote-control system allowing the user to change the frequency, pre-amp gain, sleep mode, and place the internal recorder in record, playback, and stop modes – all without ever needing to disturb talent.


To extend battery life, PowerRoll adjusts the ZMT4’s power level to 50mW when the audio received from it is being recorded by a ZaxNet compatible recorder. When the transmitter audio isn’t being recorded the power is automatically reduced to 10mW.

Modulation Choices for your Environment

The range will always vary depending on your environment, but you’ve got choices to optimise transmissPower

The ZMT4 has up to 30% better battery life than its predecessor. A single NP-50 battery provides up to 6 hours of runtime with a lavalier running at 5v and up to 4.5 hours of runtime while using a 12-48v boom microphone.



RF Modulation Proprietary Digital Method
ZMT4.5 RF Frequency Range 512 - 608 MHz
ZMT4.6 RF Frequency Range 578 - 698 MHz
RF Frequency Step 100 KHz
RF Bandwidth in ZHD96 Mode 100 KHz
RF Bandwidth in XR Mode 200 KHz
Channel Separation in ZHD96 Mode as close as 200 KHz
Channel Separation in XR Mode 400 KHz
Antenna Connector 50 Ω SSMA Female
Emission Designator 180 KV2E, 100 KV2E
FCC Part 74.861

Transmitter Audio

Dynamic Range 136 dB
Distortion 0.01%
Frequency Response Mode 0
20 Hz to 16 kHz / T & M Mode 0.2 Hz to 16 kHz
High Pass Filter Off or 70 to 220 Hz,
Steps, 10 (6dB Per Octave)
Unbalanced Lavaliere Mic Power 5.0v @ 10mA max
Balanced Mic Power 12v @ 25mA max
Balanced Mic Power 24v @ 10mA max
Balanced Mic Power 36v @ 10mA max
Balanced Mic Power 45v @ 10mA max
Mic Connector 3-Pin Micro LEMO
Mic Configuration Balanced (3-wire) / Unbalanced (2-wire)
Input Range -60 to -30 dBu
Mic Impedance 3.4 k Ω (680 Ω with 12v power mode)
ADC Bit-Depth 32 Bits
ADC Sampling-Rate 32 kHz

Timecode Reader / Generator

Clock Accuracy 1.54 PPM (1 Frame in 6 Hours)
Timecode Type SMPTE
Timecode Frame-Rates 23.98, 24, 25, 29.97NDF, 29.97DF, 30NDF, 30DF

Internal Recording

Media MicroSD Card (Flash Memory)
File Format .ZAX / Converts to BWAV or MP3

2.4 GHz ZaxNet Receiver

RF Frequency Range 2.403 to 2.475 GHz
RF Modulation Digital Spread Spectrum
RF Frequency Step 0.001 GHz (1 MHz)
RF Bandwidth 1 MHz
Channel Separation 2 MHz
Sensitivity -96 dBm


Weight 2.2 oz / 62 grams with Battery
Dimensions (H x W x D) 2.2″ x 1.6″ x .55″ / 55.8mm x 40.6mm x 14mm
Display Graphic OLED


Power Output 10 / 50 mW – Software Selectable
Power Consumption 125 mA @ 4.2v with 50mW TX (no ZaxNet or Phantom pwr)
Battery Type NP-50
Lavalier Battery Life Up to 6 hours
Phantom Power Battery Life Up to 4.5 hours