Digital Wireless Bodypack Transmitter with GainForward and SpectraBand


  • Worldwide VHF and UHF tuning range from 169 MHz-1525 MHz. 
  • Up to 12 hours battery runtime. 
  • Eco-friendly operation from rechargeable Lithium batteries or from standard AA batteries. 
  • Built-in battery charger via USB-C. 
  • Full remote control of the A20-TX via A20-Remote companion app and from A20-Nexus and A20-Nexus Go via long-range NexLink. 
  • State-of-the-art 100% digital long-range modulation delivers the longest transmission distance of any system on the market.  
  • RF Power output from 2 mW to 40 mW. 
  • Lemo input supports 2-wire or 3-wire mono lav, balanced mic, switchable 12, 48V phantom, balanced line-level, AES3, AES42 (compatible with Schoeps SuperCMIT), and guitar (w/ optional Smart Guitar Cable).  
  • GainForward Architecture – no gain control to worry about on the A20-TX. 
  • Full 10 Hz – 20 kHz audio bandwidth. 
  • 8-Series, fully balanced mic preamp built in (140 dB dynamic range). 
  • Ultra-quiet lavalier mic preamp (130+ dB dynamic range). 
  • Built-in 32-bit float, 48 kHz recorder with removable micro-SD card.  
  • Ultra-stable timecode built in, auto jammed via wireless NexLink. 
  • Sunlight-readable e-Paper screen for control and display. Display persists when powered off. 
  • USB-C for pairing with the A20-Nexus, file offload, charging, and timecode jamming.  
  • A20-TX Switch: Optional user-programmable bayonet switch, magnetically sensed and physically removable. 

A Kaleidoscope of Connectivity 

Finding a tool that can serve multiple purposes is the goal of every audio professional. More flexible gear means less — less for you to carry in a bag or fit in a case, and less gear to rent for a gig. That’s the philosophy behind the A20-TX digital wireless transmitter. We engineered it to be compatible with more input sources than any other transmitter, including two- or three-wire lavs, dynamic mics, phantom-powered condenser mics, guitars, balanced line-level sources, and even AES digital mics. The A20-TX transmitter’s multipurpose input saves you from having to pack or rent more transmitters.

True Balanced Input

The A20-TX transmitter includes an industry first: a full, true balanced ultra-low-noise, high-headroom mic preamp. In fact, this is the same preamp built into our vaunted 8-Series mixers. The A20-TX mic preamp is a big step up from the excellent mic preamp built into the original A10-TX transmitter in terms of noise, headroom, and sonic purity. 

Excellent Battery Life

The A20-TX transmitter features battery life of up to 12 hours. Additionally, the A20-TX’s flexible powering scheme allows the use of many battery types, including standard alkaline or NiMh AA batteries, rechargeable Li-Ion batteries, rechargeable LiFePO4 batteries, or even USB battery packs.   

Advanced Features 

The A20-TX transmitter boasts industry-leading features like Sound Devices’ proprietary NexLink 2.4 GHz long-range wireless remote control technology that allows multiple A20-TX transmitters to be controlled and timecode synced dependably from an A20-Nexus or A20-Nexus Go digital receiver. NexLink works over long distances – even through Wi-Fi, Bluetooth, and other 2.4 GHz interference. The A20-TX transmitter’s long-range modulation achieves excellent operational range. The A20-TX also includes Sound Devices’ proprietary SpectraBand technology, which enables the A20-TX transmitter to tune over a super wide range of 169-1525 MHz.

A20-TX Switch 

For the applications that call for a user-actuated switch, the A20-TX transmitter features the industry’s first physically removable switch. Its large size, positive tactile operation, and magnetic activation give users ultimate confidence and reliability.   


With GainForward, there is no gain setting on the transmitter! You control your A20-TX transmitter’s audio gain, either directly at the mixer’s digital trim control or at the wireless receiver, while maintaining the best audio performance in the industry. If the source is too soft or too loud, just use a downstream mixer’s digital trim gain control to make adjustments. No more bothering the talent to make gain changes. 

e-Paper Display 

You can easily view settings and menus with the A20-TX transmitter’s e-Paper Display, even in sunlight or when powered down and its batteries removed. Need to change a setting in the dark? Open the battery door and the screen’s backlight turns on for easy visibility.   

Now shipping to a retailer near you


Frequency Range
  • 169 to 1525 MHz
  • Transmitter tunable in 25 kHz steps
  • Available frequencies are dependent on region
RF Output Power
  • Off, Low – 2 mW, Normal – 10 mW, High – 20 mW, Extra High – 40 mW
Modulation Mode
  • Proprietary, 100% digital RF modulation
  • Standard or Long Range, selectable
  • UHF RF: SMA connector, removable antenna
  • 2.4 GHz built-in, bottom of unit
Audio Frequency Response
  • 10 Hz – 20 kHz, +/- 1 dB re 1 kHz
Audio Input
  • Lavalier Microphone
    • 2-wire- or 3-wire-type lavalier mics supported
    • Auto-selected when lavalier mic connected to Lemo input
    • Dynamic range: 130+ dB min, A-weighted
    • Input clip level: 5V p-p (limited by lavalier microphone)
    • Lemo pin 1 = ground; Lemo pin 2 = 5V bias power; Lemo pin 3 = audio/bias (8k to 5V internal)
    • Auto unit power on/off with connection/removal of lavalier microphone (menu selectable)
  • Balanced Mic
    • True, fully balanced, 8-Series mic preamp
    • Dynamic range: 140 dB min, A-weighted
    • Menu selectable with connection of XL-BALXLR-4 cable to Lemo input
    • Phantom power: 12V or 48V, full 10mA available per IEC 61938
    • XLR pin 1 = ground; XLR pin 2 = +; XLR pin 3 = –
  • Line Input
    • True, fully balanced line-level input (no external resistors required)
    • Input clip level: +26 dBu
    • Menu selectable with connection of XL-BALXLR-4 cable to Lemo input
    • XLR pin 1 = ground; XLR pin 2 = +; XLR pin 3 = –
  • AES42
    • AES digital input with common mode power for Digital mics such as Schoeps SuperCMIT
    • 250mA current available
    • Selectable audio channel 1 or 2 via menu
    • Menu selectable with connection of XL-BALXLR-4 cable to Lemo input
    • XLR pin 1 = ground; XLR pin 2 = +; XLR pin 3 = –
  • AES3
    • AES digital input without common mode power
    • Selectable audio channel 1 or 2 via menu
    • Menu selectable with connection of XL-BALXLR-4 cable to Lemo input
    • XLR pin 1 = ground; XLR pin 2 = +; XLR pin 3 = –
  • Guitar
    • Auto-selected when connected with A20-TX Smart Guitar Cable
    • ¼” tip = + ¼” sleeve = ground
    • 18V p-p max input level
    • Input impedance: 100k, 1M, 10M (menu selectable)
    • Cable capacitance: 0 pF – 3000 pF in 50 pF steps (menu selectable)
    • Balanced connection from ¼” plug to Lemo for low noise susceptibility
Menu and Controls
  • e-Paper screen highly visible in direct sunlight
  • e-Paper screen keeps display even with no batteries
  • Power/Pair button and three navigation buttons protected inside battery compartment
  • Optional user-programmable bayonet switch for top of transmitter (A20-TX Switch)
Remote Control
  • A20-Remote Android, iOS, and iPad app via Bluetooth 5.2 LE
  • A20-Nexus, A20-Nexus Go receivers via super-long-range NexLink
Recording Media
  • Micro SD card
Recording File Format
  • 32 Bit Float, 48 kHz, Monophonic
  • Broadcast WAV (<4 GB), RF64 WAV (>4 GB)

Simultaneous Record and Transmit mode when using lavalier mic input is not available on A20-TX units sold or operated in the United States of America.

  • Input via XL-TC-USBC-LEMO, XL-TC-USBC-BNC, USB-A to USB-C (from 8-Series) or wirelessly over NexLink (from A20-Nexus/A20-Nexus Go)
  • LTC: 0.3 V – 3 V p-p (–17 dBu to +3 dBu), 20k ohm impedance
  • LTC Output via XL-TC-USBC-LEMO: 3 V p-p, 400 ohm impedance
Timecode Clock
  • 0.2 ppm accuracy
  • Holds accurate clock for four hours while powered down with batteries inserted, holds for one hour without batteries via internal supercapacitor
  • Auto Jams timecode via USB-C connector or wirelessly via NexLink
Timecode Frame Rates
  • 23.98, 24, 25, 29.97 DF, 29.97 ND, 30 DF, 30 ND

Frame rates are auto-detected from incoming source

  • Mass Storage (USB-C): USB 2.0 high speed for file transfer
  • Charges Li-ion and LiFePO4 batteries inserted in A20-TX
  • Pairing to A20-Nexus, A20-Nexus Go
  • Timecode I/O
  • “1.5V” Alkaline, Lithium primary, NiMH AA batteries; 3 for operation
  •  “3.7V” Rechargeable Lithium-Ion, Rechargeable LiFePO4 AA batteries; 1, 2, of 3 for operation
  • Energizer Ultimate AA primary cells recommended for longest runtime
Battery Charging
  • Built-in charging of Lithium-Ion and LiFePO4 batteries via USB-C
Battery Runtime
  • Up to 12 hours (depending on battery chemistry, number of batteries, RF power, input type, mode)
  • Unit can be completely powered off remotely via app or via NexLink to extend battery runtime 
  • Operating: -10° C to 38° C
  • Storage: -40° C to 85° C
  • 0 to 90% relative humidity (non-condensing)
Dimensions (H x W x D)
  • 3.3 x 2.5 x 0.71 in 
  • 8.5 x  6.4 x 1.81 cm
  • 0.2lbs (without batteries)
  • 98g (without batteries)



How does the A20-TX compare to other Sound Devices transmitters in size and weight?

The table below details the size and weight for the different transmitters:
A10-TX A20-TX A20-Mini
Dimensions (H x W x D)
  • 3.3 x 2.5 x 0.7 in
  • 8.3 x 6.4 x 1.8 cm
  • 3.2 oz (without batteries)
  • 104 g (without batteries)
Dimensions (H x W x D)
  • 3.3 x 2.5 x 0.71 in
  • 8.5 x 6.4 x 1.81 cm
  • 3.2 oz (without batteries)
  • 98 g (without batteries)
Dimensions (H x W x D)
  • 2.98 x 1.88 x 0.74 in
  • 7.58 x 4.8 x 1.9 cm
  • 1.6 oz (without batteries)
  • 51 g (without batteries)


What are the battery powering options

The table below details operational characteristics for the different recommended AA battery chemistries:
Battery Chemistry Recommended Model Required No. of Batteries Chargeable in the A20-TX
NiMH Eneloop or Eneloop Pro 3 No
Alkaline Energizer or Duracell 3 No
Lithium Primary Energizer Ultimate Lithium 3 No
Li-Ion Xtar 14500, 3.7V, 800mAh 1, 2, or 3 Yes
LiFePO4 Shockli 3.2V, 650mAh 1, 2, or 3 Yes


A20-TX Smart Guitar Cable


A20-TX Guitar Strap Clip


A20-TX Switch


Astral VHF Whip Antenna (SMA)






In Action

Dustin Fleetwood Crafting Cinematic Magic with Sound Devices