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Audio Ltd RMS 2040 Series

Each rack includes active antenna distribution with two BNC inputs and outputs, allowing two antennas to be shared between two racks (eight channels in 2U of space).

UK-based Audio Ltd. has been involved with audio for film and TV production since the 1960s. It’s one of the industry’s leading brands when it comes to wireless audio for film and TV. You can find products like the 2020 radio system adorning the shelves of the UK’s biggest production and rental companies.

The new RMS 2040 range, design for both the studio and theater markets, includes a rack-mounted receiver for two to four channels, and a selection of transmitters for specific applications.


The heart of the 2040 system, containing two to four receivers in a 1U space, the RK2040 can be powered from any DC source between 10v and 18v, even a car battery will work. Once you get a power source connected, simply fumble with the very well protected power switch till it clicks, and the unit will initialize each screen in order. There is no hanging about for the system to boot up, it’s ready from cold in about six seconds.

Each rack includes active antenna distribution with two BNC inputs and outputs, allowing two antennas to be shared between two racks (eight channels in 2U of space). The whole design and concept is optimized for minimum size, the result is a feature rich package at least half the size of just about anything similar on the market.

Using the system could not be any easier. A screen is dedicated to each receiver displaying the state of audio and RF levels and also the name, frequency, battery level, and audio output level of each transmitter. The necessary information is displayed clearly in dark conditions thanks to the backlit LCD screens, with adjustable brightness and contrast settings to suit.

When you need to change a receiver setting, the four push switches adjacent to each screen provide a quick way to navigate a simple menu system. All the settings for the receiver can be changed from here, and information from a currently tuned transmitter may be monitored here, like the battery level. The RF level and audio level are also displayed.

The connection panel on the back includes two antenna inputs and two antenna outputs on 50 ohms BNC posts. The power input is a 4-pin XLR connector, for use with the supplied mains transformer or sources like a camera battery pack – anything DC between 10 and 18 volts will work. Two 9-pin D-Sub connectors are used for the computer bit, which uses RS485 to communicate with a PC up to 1000m away over twisted pair cable. By connecting adjacent racks in a daisy chain, up to 48 receivers can be controlled by the PC.

Audio Ltd.’s audio quality, delivered by the 2040 system, does not disappoint. With a 24Mhz switching band, enough information is squeezed down each channel to ensure a high fidelity signal with increased reliability and consistency. By using high quality components throughout the design, like the Sowter transformers on each output, Audio Ltd. has managed to deliver a fantastic sounding system.

Of course, the antenna you choose to use and the way in which you set up any radio system will affect performance and range, but with a little advice from the user manual (supplied on a CD) even the novice should have a rock solid system in no time.

The review system was delivered with two dipole antennas fixed to a clamp, and two of the standard ‘whip’ varieties. The audio outputs are provided on gold plated XLR connectors, each one being transformer balanced and adjustable from line level down to mic level.

This very compact MiniTX Beltpack Transmitter is about the size of a credit card, with enough thickness for two 1.5v AAA cells. The belt-clip can be removed by sliding it off the pack, leaving a smooth oval rectangle that sits in the provided cloth pouch and is very comfortable to wear. This box of tricks is very light, and much easier to conceal than previous systems. The best thing about it has to be the talent-friendly remote control, which means you don’t have to handle the unit until a change of batteries is required.

At the top of the pack, you find a smooth ‘dome’ with recessed connectors for the antenna (SMA connector) and microphone (LEMO connector). The dome conceals some LEDs and infra-red ports for the remote control, which is the only way to adjust pack settings. There are really two different types of remote control; the infra-red version is like a car alarm key fob with four buttons to navigate through each menu, while Control-X uses magnetic induction (like a hearing aid) to transmit through clothing and switch transmitters on or off, and display other information like frequency.

The battery compartment is hidden under the end of the pack, which pivots in the middle like a swinging bridge to reveal the two AAA cells. On the ‘body’ side of the pack, the clear graphics tell you not only how to insert the power cells, but also sports a proud “Made in the UK” statement.

All the tools are here for a great way to deal with wireless mics on set. The transmitter pack can be fitted with fresh cells, programmed with the controller and given out to the talent. If further tinkering is required, there is no need to remove the pack and start poking about with a ball point pen, simply zap it with a remote – after all, we’ve been doing it to our televisions for years. It’s a great idea, eliminating bulk, cost, and lots of buttons for people to fiddle with. There is no need to lock the pack, as the only way to turn it off locally is to remove the microphone plug.

Fast FactsApplications
Audio for film and television studio; theater audio

Key Features
Based on two to four receivers in a 1U space; powered by any DC source from 10 to 18V; includes active antenna distribution with two BNC inputs and outputs; industry leading small size

Priced upon application/configuration

Audio Limited | 44 1494 511711 | www.audioltd.comSetting the frequency took a little time to get used to, the remote tended to work from one angle only, and a distance of about 20-30cm in a ‘line of sight’ arrangement. The IR beam is very narrow, I found you must aim the remote exactly at the pack you wish to adjust, pointing down the antenna towards the IR sensor. After a while you can be quite precise with the remote and you get used to where it needs to be.

The supplied software, ‘Racktop’, can monitor the system with clear understated graphics, edit settings, and provides some well designed tools to get the job done without fuss.

Opening up the racktop software is easy, but you do have to connect to active units before they will appear on the screen. Connecting to the unit(s) is a little bit involved, as you need to have a Windows computer and various adaptors to end up with RS485 on a 9-pin D-sub connector. It would seem the reason for this is the long range. You can communicate with a rack (or racks) up to 1,000m away, and that’s a big film set. I would still like to see a USB socket on the rack though, as not everyone needs to be so far away, and the extra cables and adaptors are bulky enough to be awkward.

In Use

Once you are able to see the rack(s) in the software, you are in business. I first tried using a Powerbook G4 and virtual Windows – no joy, but the desktop PC worked first time. I needed a USB-RS232 adaptor followed by a RS232-RS485 adaptor to make it all work.

The dynamic display is the default, and provides information about each receiver name, RF, and audio levels. Once you have connected a rack it is a snitch to see all the levels and details like a name for each user.

Advanced features include a ‘scan channels’ graph with the 32 frequencies of the system along the horizontal, while signal strength is indicated vertically. If a transmitter is detected a bar will indicate the currently tuned frequency, and if the transmitter power is on or off. Using a matrix like grid of checkboxes, you can choose any receiver and log the audio level and RF level into a time stamped CSV file, viewable in spreadsheet software like Excel.

Being able to scan the radio spectrum for ‘gaps’ is used extensively in the live sound industry, with the help of a computer this is now easy on location too – by using the infrastructure of the 2040 system a compatible frequency set can be constructed from the installed frequencies.

To ensure stable reception from the transmitters, the receivers employ true diversity reception. The RF is constantly monitored in each receiver and the audio is switched noiselessly to eliminate drop-outs.

There are 32 pre-programmed frequencies to choose from; the supplied kit operated between 838.100 and 861.750, but just about anything can be ordered in line with local regulations.

Next, the HX2040 is a handheld transmitter. Through a very classy relationship with Schoeps microphones, the microphone can accept any of the 20 capsules from the ‘Colette’ range, regarded for their transparent audio response and fine detail by many engineers. Slick features include an infrared control interface, integrated pop shield, shock-mount, and just one button labeled ‘on’. The single 1.5v AA power cell is enclosed inside the tailpiece, once you close this up it also acts as the antenna. The review kit did not include the HX2040 but if the build quality of the other units is anything to go by then it should be good with solid features.

The TX2040 is a more standard sized transmitter already used for wireless audio. The design incorporates the latest advanced technology to enhance multi-channel operation with a switching bandwidth of up to 24MHz and 32 pre-programmed frequencies.

The DX2040 portable true diversity receiver has Audio’s unique infra-red interface allowing the user to set all parameters via the SwitchiR, a keyfob-sized remote control unit.

The receiver can be internally powered from two 1.5V, AA (LR6) type batteries giving up to five hours use on good quality alkaline batteries (longer using lithium type), and externally powered (with a supply range of 6-18V DC) using cables available from Audio and mounted on a camera easily.

A standard six pin Lemo connector interface means existing cables can be used, and the receiver is fully backwards compatible with Audio’s older RMS2020 and RMS2000 ranges.


The whole RMS 2040 Series by Audio Ltd. is ultra compact and uses very modern lightweight materials with great strength. ?By integrating features usually obtained by using extra equipment, such as antenna splitters, you can be sure that the components of the system are correctly aligned and operating efficiently.