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AKG DMS70 Quattro

Wireless Microphone System
Published May 2012
By Mike Crofts

Thinking of going wireless? If you value audio quality and ease of use, this digital system from AKG might be just what you're looking for.

AKG DMS70 Quattro

Wireless microphones for live sound offer many benefits, including freedom from trailing cables and connection problems, but they can also suffer from interference, poor audio performance and fiddly setting-up procedures. The new DMS70 system from AKG aims to deliver all of the benefits without the associated problems. Unlike many digital systems, it doesn't compress your audio. Instead, it uses 24-bit/48kHz PCM, and is therefore a very appealing prospect worth a closer look.

Wireless systems are a bit of a hot discussion topic at the moment, as the UK frequency allocations are changing. The existing UHF licence-free band between 863 and 865 MHz remains available, but will tend to become more crowded as users who can't justify investing in new equipment stick with the 'free' channels. There are new UHF channels for licensed and shared frequency operation in the old TV channel 38, but there is another and potentially congestion-free option in the form of the worldwide, licence-free 2.4GHz standard, used for low-power wireless devices such as Bluetooth and wireless local networks. The DMS70 is a digital wireless system operating in this 2.4GHz range, and as such can be used anywhere on the planet without any licensing issues. As there are no broadcast (ie. high-power) transmissions in this band, there should be no problems with external interference, but other nearby devices using 2.4GHz should ideally be switched off. As this is a digital system, the signal from the mic transmitter is encoded using 128-bit encryption, and can therefore be assumed to be secure for all normal purposes.

Have It Your Way

AKG DMS70 Quattro

The DMS70 is available in a number of different 'boxed set' configurations, with either a twin- or four-channel receiver. The two-channel receiver is called the Dual, while the four-channel version is called the Quattro, and comes with either a pair of handheld mics, a pair of beltpack transmitters, or one of each. All the individual components are available to buy separately, which is a plus point (and not the case with all manufacturers!) if you want a bespoke system or just need to add additional units at any time. I took the DMS70 Quattro Vocal Set for a spin, which was very convenient, as I had two live sound jobs coming up that required two vocal microphones.

The DMS70 set arrived in a suitcase-style shipping carton with a carrying handle, so I left it in that and took it along to the first gig. For this job I only needed two handheld mics, so it was simply a matter of unpacking the receiver, connecting it up and putting batteries in the mics. The receiver (model number DSR70) is a very neat device and is about three quarters of the width of a standard rack unit. It is supplied with a pair of very strong rack ears, which is a nice quality touch, and as these are actually cast metal they hold the unit very securely, with no additional support needed.

The DSR70 requires a 12V supply, which is provided by a PSU with about 2m of cable, and the rear-panel connector is easy to access and has a strain-relief bar alongside. There are five balanced XLR outputs on the back: the four receiver outputs, and a mix output, which can be used either for monitoring or as a main sum out for very basic applications where an external mixer isn't really necessary. I sat the receiver on top of my own receiver rack (brought along just in case, as you do) and powered it up. The on/off switch lit up in green and displayed the universal power symbol. It's a small point, but I think this lit button is a good practical design feature, and may just prevent an inexperienced operator from pressing it in a panic and switching the whole system off.

Both the receiver and the transmitter (the microphone, in this case) have LEDs to indicate that the two are properly connected.Both the receiver and the transmitter (the microphone, in this case) have LEDs to indicate that the two are properly connected.

Nothing else happened at this stage, as I hadn't switched the mics on yet: the DMS70 is a bi-directional system whose transmitters and receivers send control information to each other, so you can see from the receiver which channels have an active microphone associated with them. The receiver's two small, plastic-covered antennae are permanently fixed to the front panel, and fold down out of the way when packing. They can sit at three set angles (flush with the panel, or at 45 or 90 degrees), and I like the fact that they click into place, because it means that even after much wear and tear, they won't become loose and start to droop.

With the microphones both 'batteried up', the next step was to switch them on. The DMS70 set is shipped with the two supplied mics already assigned to channels 1 and 2, so as soon as I pressed the microphone 'On' buttons, the associated receiver channel lit and the system was up and running. For confidence, there's a large green LED on the side of the mic that lights up when connection with the receiver is established. If the LED is flashing, there's no communication between the two, which means that you're out of range or the receiver has lost power (as opposed to the mic simply being switched off). This is a novel and useful feature, as it indicates to the person holding the microphone that they are entering dark territory. The receiver LED, meanwhile, simply turns off when contact is lost, as it is picking up no control information from the mic transmitter.

While I'm on the subject of LEDs, flashing or otherwise, another really useful feature is that when the receiver is turned off, using the front-panel switch, all transmitters will also turn off, thus preventing one being accidentally left on after a show. One thing you can't do is switch any of the mic transmitters on from the receiver end, which is a pity, because once certain mic users (especially those speaking at meetings and presentations) discover that there is a switch, they will invariably press it and then forget to switch it on again before speaking. I've often longed for a remote 'On' function that could replace the frantic hand-signals and mime routine from the back of the room, and which often results in the mic user pressing the button twice more, and so on... Anyway, setting up was completed in about two minutes, including unpacking the DMS70 components from their shipping box, and it was all working as it should.

Good Impressions

Inside the microphone is a button for linking it to a specific channel on the receiver, and a switch to select between high and low gain.Inside the microphone is a button for linking it to a specific channel on the receiver, and a switch to select between high and low gain.

In terms of audio performance, the DMS70 system sounded very nice indeed, and I and my clients were impressed with it right from the start. The handheld DHT70 transmitters use AKG's D5 capsule, which just happens to be my dynamic stage mic of choice for almost everything these days. I've been using a caseful of these for the last couple of years, I love their sweet, clear sound, and the supercardioid pickup pattern is ideal for live work. As mentioned earlier, the DMS70 is an uncompressed system using 24-bit/48kHz wireless transmission, and the sound quality is impressive: as far as I could tell, these mics sounded exactly like my own wired D5s. Each transmit/receive channel uses two antennae for diversity (even the mic transmitter has twin antennae), and the system also selects clean frequencies automatically (AKG call it Dynamic Frequency Selection), to keep everything running smoothly and free from clutter.

The DMS70 set comes ready to use out of the box, but if, for some reason, the transmitters are not aligned with the receiver, or you want to change one of the mics to a different receiver channel, it's a very simple matter. This involves pressing a single button on each device, and the process can be initiated from either the microphone or the receiver by pressing and holding the 'connect' button by the battery compartment (or 'link' on the receiver) for a couple of seconds. The green LED starts flashing, a clear frequency is allocated, and all you do is press the same button on the other component, and the two are linked and ready to go. It really is very straightforward, and because the frequencies are allocated and registered automatically, there's no opportunity to get it wrong.

Take Two

The wireless mics included in the Vocal Set are fitted with AKG's D5 dynamic capsules.The wireless mics included in the Vocal Set are fitted with AKG's D5 dynamic capsules.

For my second road test, I took the system along to a concert where I was working with two solo performers, one male and one female, backed by a live band. Again, setting up the DMS70 was very quick and trouble-free, and we were operational within minutes. For various reasons, we had to forgo a full soundcheck on the day, but as we had rehearsed in the same venue a few days before (with wired D5 mics), I was happy to go with a quick 'one-two' and check the levels on the desk. I gave the singers a mic each, with strict instructions not to touch the on/off switch, and it was only when they went either side of the stage for their entrance that I realised I hadn't checked which mic was which. The DHT70 isn't supplied with a colour marker, so I retrieved both transmitters and put a piece of tape around one so that I could identify it from the mix position.

I expected the vocal sound to be very good, and it certainly was; both singers commented that they really liked the mics, and found them light, well-balanced and generally a pleasure to use. Although I didn't need to change it, there is a high/low sensitivity setting on the microphone transmitter, which I left set to 'high' with no problems. I hadn't replaced the batteries after the first outing, so after the second gig, they had clocked up around three hours of use. I wanted to observe the 'low battery' warning on the receiver, so I left them on when I got home, but after another hour they were still going strong, so I called that particular experiment off (as I always 'change or charge' between sets, I reckon four hours on one set of batteries would see me through any event).

Home On The Range

With wireless communications, the higher the transmission frequency, the more maintaining a direct 'line of sight' between transmitter and receiver is important, to avoid drop-out, and the DMS70 has a published maximum (line of sight) range of 30 metres both indoors and out. When using radio mics in even medium-sized venues, I like to place the receiver near to the stage to ensure good reception, and then send the outputs from that down the multicore. On both live events with the DMS70, however, I found no problems with using the receiver at the back of the venue, which in both cases was about 15m to 20m from the performers, and with quite a lot of audience in between. Back at home, I managed to get a pretty strong signal two rooms away, and I had to put four walls (it's a long, thin house) between the microphone and receiver before I lost transmission altogether.

The DMS70 system is very definitely plug-and-play of the most uncomplicated kind, and offers excellent live performance with several useful additional features. Apart from the uncompromised sound quality, I like the stability of the system and simplicity of operation. I'd have no hesitation in hiring this out to an inexperienced user or recommending it for a multi-operator application such as a school, church or community venue. Two Quattro receivers can be used together, enabling a maximum of eight simultaneous channels, and, of course, the beltpack transmitter options offer the opportunity to connect instruments and other compatible sources. Having got used to the extra functionality of the DMS70 compared to my own wireless setup, I would really have liked the ability to switch individual mics on and off from the receiver, but apart from that, I think the DMS70 is a great-sounding and thoughtfully designed system that is well worth closer investigation if you're looking for stage-ready wireless operation.  

Alternatives

Line 6's XD systems are among the only other wireless products that operate in the same 2.4MHz band as the DMS70.

Published May 2012

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