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Sound Devices NEXUS Multichannel receiver 470-1525MHz SpectraBand
A20-Nexus
8-16 Channel True Diversity Receiver with SpectraBand Technology
The future of wireless
Meet the half-rack receiver with an entire rack's worth of features. The next-generation A20-Nexus is expandable from 8 channels up to 16 channels with software licenses and features forward-thinking technologies like SpectraBand, the powerful NexLink remote-control link, real time spectrum analysis, and more. With multiple options for audio outputs, powering, and remote control, the A20-Nexus can seamlessly adapt to your workflow, both now and in the future.
SpectraBand
SpectraBand technology delivers a tuning range of 470 – 1525 MHz in a single unit – an industry first. Experience ultimate flexibility as you find open spectrum away from the crowded UHF TV band. The included A20-Monarch antennas can receive the entire 470-1525 MHz range, keeping your kit small and tidy.
NexLink
Control your A20-Mini transmitter using the built-in long range remote control link. NexLink’s advanced long distance modulation reaches even farther than the A20-Mini’s long-range audio transmission.
Network away
You’ve got options. Configure your A20-Nexus for Dante audio, use the built-in web server to control the receiver using the web browser on any computer, tablet, or phone, and even power the A20-Nexus remotely using Power-over-Ethernet (PoE).
Real time spectrum analysis
The days of waiting for a frequency scan to complete are over. Instantly visualize the fluctuating RF spectrum around you in real time – while running all channels of the audio.
GainForward
With the A20-Mini’s GainForward Architecture, easily set the Mini’s gain, low-cut, and limiter directly on your A20-Nexus or mixer-recorder. This immediate, local control of gain means never having to adjust the gain on the transmitter again.
Go cableless
Thanks to its half-rack size, the A20-Nexus is equally at home in a rack, in a bag, or docked to an 8-Series mixer recorder for a cableless kit.
Long range
The A20-Nexus and A20-Mini deliver the longest transmission distance of any system on the market.¹ The state-of-the-art, 100% digital long-range modulation offers the same great audio quality (10 Hz – 20 kHz) as our Standard modulation scheme with a longer range for both line-of-sight and heavy multipath transmission.
Shoot for the stars
The A20-Nexus joins the growing lineup of Sound Devices Astral™ wireless products. With industry-leading features like SpectraBand, GainForward, NexLink, long range modulation, real time spectrum analysis, and more, the Astral Series pushes the bounds of wireless audio.
Expandable to 12- or 16-channels via software license (coming soon)
470 MHz – 1525 MHz tuning range via SpectraBand Technology
NexLink: integrated, long distance remote control of all wireless transmitters
Dante audio-over-IP of RF receiver audio
Flexible powering: via PoE+, DC input, 8-Series, or AC mains (with optional adapter)
Web App control from browser on any computer, smartphone or tablet
Full remote operation capability: Power via PoE, audio via Dante, control via Web App
Dual DB-25 connectors for 16 channels of mic, line, or AES outputs
16 channels of Dante audio-over-IP output to DB25 connectors on the back panel
Wide, 6.2” color OLED array with touch for control and monitoring
Integrated Real Time Spectrum Analyzer (RTSA) and scanning for intuitive frequency coordination
Optical Fiber Network option via SFP slot. SFP accepts a wide variety of modular network transceivers
A20-QuickDock allows docking and undocking in seconds from 8-Series mixer-recorders with no tools
Supports GainForward Architecture: No gain setting on the A20-Mini transmitter. Adjust gain at the receiver or mixer
100% digital long-range modulation delivers the longest transmission distance of any system on the market
Excellent audio quality, full 10 Hz – 20 kHz audio bandwidth
RF SAW filters for excellent rejection of interference from nearby IFB or camera hop transmitters
BNC timecode input for auto timecode sync of transmitters over NexLink
SpectraBand Explained
Last updated August 25, 2022
SpectraBand is a brand-new technology which gives the A20-RX receiver and A20-Mini transmitter an unprecedented tuning range: 470 MHz – 1525 MHz. The advantages of SpectraBand to sound professionals are many:
More operating frequencies are available in a given location, alleviating the problem of no open spectrum to operate wireless mics.
Money is saved by purchasing only one piece of gear, which can be used anywhere, rather than special hardware variants of kit used for different locations.
Worldwide travel is easier, as the A20-RX and A20-Mini can use all legal frequency bands within their tuning range in any given country.
The SpectraBand hardware includes exceptional filtering that improves immunity from strong interfering signals (for example, a local DTV transmitter) or other transmitters close to the receiver (IFBs, 2-way radios, camera hops).
For reference, in the USA, SpectraBand provides access to approximately 285 MHz of available spectrum:
The entire UHF TV Band (470-608 MHz)
The 600 MHz Guard Band (614-616 MHz)
The 600 MHz Duplex Gap (653-663 MHz)
The 900 MHz ISM Band (902-928MHz)
The 950 MHz STL Band (941.5-960 MHz)
The 1.5 GHz AFTRCC Band (1435-1525 MHz), with an appropriate license.
In the UK, SpectraBand provides access to approximately 383 MHz of available spectrum:
The core UK UHF TV Band (470-702 MHz)
The 800 MHz Duplex Gap (823-832 MHz)
The 800 MHz SRD Band (863-865 MHz)
The DME bands (961-1015 MHz, 1045-1075 MHz, 1105-1154 MHz), with an appropriate license.
The IMT band (1518-1525 MHz)
This is not a comprehensive list of countries and their available bands. Visit this page to see frequencies available in other countries.
Several key technologies enable SpectraBand’s incredible range. These include brick-wall, SAW-based front-end filters, a wide-range local oscillator (LO), wide-range modulator/demodulator, and a high dynamic-range low-noise amplifier (LNA).
Filtering
In any RF system, proper filtering is necessary for excellent performance. Any time an amplifier is utilized in the signal chain, the amplifier must be preceded by a filter, or poor performance will result depending on the operating environment. This filtering prevents amplifier overload and the resulting distortion products which reduce operating range for the user. In an audio system, clipping of an amplifier is easy for a user to hear and remedy. This similar mechanism (RF amplifier overload) can be difficult to perceive in an RF system as everything can appear and sound ok, but the result (instead of distorted audio, as is the case in an audio system) is reduced operating range. Just as a audio bandpass filter helps an audio engineer deal with noise, a good RF filter helps an RF amplifier from misbehaving. The sharper the passband filter that can precede an RF amplifier without attenuating the wanted carrier, the better.
Shown in this picture is the A20-RX’s brick-wall SAW filter compared against two traditionally designed and well-regarded tracking filters currently on the market. The yellow trace is the A20-RX’s SAW filter centered at 573 MHz, the blue is competitor 1 and the green is competitor 2. As can be seen, the A20-RX’s filter exhibits a brick-wall type of response, being over 45 dB down at 603 MHz, while competitor 1 is down only about 2 dB, and competitor 2 is down only about 12 dB. This plot illustrates very clearly why the A20-RX’s filter can operate in closer proximity to strong interference with no change in performance: if an interferer (DTV or other transmitter) is at 603 MHz, it is greatly attenuated by the SAW filter and does not change performance of the A20-RX. The A20-RX has a network of over 40 fixed SAW filters on the A and B antenna inputs. These filter ranges have been carefully selected for broad compatibility with Program Making and Special Events (PMSE) and DTV wireless spectrum worldwide. Brick-wall SAW filters allow for unsurpassed immunity to out-of-band interference.
Local Oscillator (LO) and modulator/demodulator
In a wireless mic transmitter, digital audio signals must be up-converted to radio frequency (RF) signals with a modulator chip for transmission through the air. This modulator is driven by a local oscillator (LO). Both the modulator and LO need to be designed with extreme care in order to operate reliably from 470 MHz – 1525 MHz. Sound Devices uses the latest in low-current, low phase-noise LO and field-programmable gate array (FPGA) design to satisfy these requirements, which were simply not available just a few years ago.
Likewise, a wireless microphone receiver needs to down convert the received RF signal back into digital audio data. This down conversion is done with the very latest high-quality flexible demodulator and LO. The A20-RX uses a proven dual downconverter superheterodyne topology with extensive SAW filtering to ensure the best possible selectivity (see picture below). This takes more parts than other topologies, but ultimately results in excellent nearby signal rejection, yielding improved operating distance.
Low Noise and High IP3 LNA
Much like a mic preamp in an audio system, a low-noise RF amplifier (LNA) is the first active device in an RF signal path (see item 2 in the picture above) and can define the quality of the entire system following it. For high performance, a quiet LNA is necessary. The Noise Figure (NF) specification quantifies how quiet the LNA is. A low NF will allow for very long-range operation, much like a good, quiet mic preamp allows for recording of very low acoustic levels. However, a quiet LNA is only half of the equation. The overload of an LNA is specified by its 3rd-order-intercept point (IP3). Again, back to the mic preamp analogy, the IP3 of an LNA is like the headroom of a mic preamp. If the IP3 of the LNA is too low, strong interfering signals, whether from a nearby 2-way radio or other strong transmitter near the receiver can overload the LNA, generating distortion, and greatly reducing the operating distance of the wireless microphone system. The Sound Devices A20-RX uses the very latest in E-pHEMT transistors, utilizing an LNA which has a NF of just 0.3 dB while simultaneously offering +39 dBm of output IP3: super quiet, with loads of headroom.
Conclusion
Whether you work locally or travel worldwide, the A20 System gives you a wider choice of operating frequencies. As the wireless spectrum becomes increasingly crowded, having extra flexibility in tuning range is imperative. The A20-RX is the only digital receiver on the market that can tune not only in common UHF TV bands around 470 – 608 MHz, but also far above that.
If you wish to purchase in store, to avoid disappointment, please confirm the availability of the product at your local John Barry prior to visiting.
Alternatively, orders placed online by 2pm AEST are typically dispatched same day, if ordered online.
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