Iain Betson pairs up with the latest addition to A-T’s wireless range...
In light of the changes that have occurred to the availability of RF spectrum allocated to radio microphone use in the UK, I can see why manufacturers are now producing equipment that operates in the 2.4GHz range.
The obvious attraction for the user is that these systems are licence free, immune to audible interference and offer more channels. For the producer, only having to comply with one international standard makes production and distribution far more efficient.
The downside is that, while I said free from audible interference, with so many devices using it – all of which are competing for their own bit of spectrum – the chance of failing to obtain a channel in the first place, or the link dropping out when it does, is more than a remote possibility, especially when used in ‘2.4GHz rich environments’, such as hotels or auditoriums.
A way to increase your chances of grabbing, and holding onto, a channel is to move the transmitter and receiver close to each other. As higher RF frequencies prefer line-of-sight links, the received signal strength will be the best and as consistent it can be. The problem here is that large venues or productions may not permit such convenient co-siting. An alternative is to locate the reception antenna from the receiver remotely and reduce the distance this way. However, at the power and frequencies these systems operate on, such a setup will require feeder cable as thick as your arm if losses between antenna and receiver are to be minimised.
The Audio-Technica System 10 PRO employs a variation of the remote antenna approach, in that the whole antenna/receiver block can be located remotely from the audio/tuning section. There will be more about this later.
Starting with the obvious, it’s called the System 10 as, fully spec’d, it can simultaneously support 10 transmitter/receivers. And it’s called the Pro as it offers facilities and functionality over that of the ‘prosumer’ System 10 product Audio-Technica introduced a while back.
The base unit is a 1U-high, half rack-width chassis that can house and connect to two receivers. As delivered, you receive all the rack hardware to join two chassis together, to fit 1U of rack space, as well as a half rack-width blank plate to mount just a single device. To rack up a fully spec’d system, you will require 3U of space with one receiver using a blank plate. You will also be left with spare blank plates and joining hardware.
At First Glance
My initial impression of the chassis is that it is a solid, well-put-together box.
The front panel is fairly clutter-free, comprising a decent quality rocker-style power switch; perhaps this could have been ideally located on the rear, but its surround makes inadvertent operation unlikely. Two flap-covered slots, for the receiver blocks to slide into, sit either side of a display and buttons that are used to operate and check the status of each link.
The receiver blocks are about the size of a cigarette packet. Each has two antenna sockets on the front. The supplied 45mm-long antennae screw onto the blocks and can be rotated and angled to improve reception. Inserting the blocks into the chassis is easy: they simply push against the cover, slide in and lock. Releasing them is done via a slide switch under the slot. The base of the block has an RF connector socket, an RJ45 data connector, four pad contacts and a green operation LED. When in the chassis, the block makes use of this RF connector and the four pads to make a connection, but when sited remotely the RJ45 is used.
Using a data network connector is an interesting solution to remotely siting the receiver block, since it allows the use of existing structured cabling within a venue, obviously on its own dedicated point-to-point link. As only the four pad connectors are used when the block is chassis mounted, I assume that only two of the pairs of the data cable are used when it is remotely located: one for power and another for signal transfer. Of the latter, I am not sure of the format used by the System 10 PRO, but Audio-Technica states the receivers should be located no more than 100m away from the base unit, so I assume it is digitally based. During my tests, I ran the link over a cable run by connecting three Cat5e leads together with back-to-back couplers to simulate the signal running through patch panels. The combined length was a little in excess of the 100m, but still I found all worked well.
An Easy Fix
To facilitate their remote mounting, also supplied in the kit are two light grey caddies into which the receiver blocks slide. Screw holes in the caddies allow easy fixing to a surface or, there not being much weight involved, Velcro tape would probably do the job too. I pondered on the colour of these caddies as, against the black background of most stages they might show up, but then again these units may be located in a the public area of a conference venue in which case black may not be best.
The green LED on the rear of the block lights up when the unit is powered, acting as a useful system check.
The back end of the chassis frames are quite busy. Both receivers (pictured, above) have two outputs: balanced on an XLR and unbalanced on a 6.35mm diameter jack – the signal output of the former connector being at mic level, while the latter is at line level.
A single trim control adjusts the level on both connectors. Below this control is a ground lift switch which disconnects pin 1 of the XLR to, as it says in the manual, “avoid hum if a ground loop occurs”.
I would say one of the potential causes of hum could be that the chassis is powered by a ‘wall-wart’ plug-top power supply and using such a method is a minor gripe. It would have been nice to see an integral PSU in the case, after all the product is badged as ‘Pro’. This mode of powering also leads onto a refinement that I think A-T could have implemented. I will come onto this later.
Also on the rear panel is an RJ45 connector to facilitate the remote connection of the receiver block. This is a nice touch since it keeps the remote link wiring out of the way.
Finally, there is a pair of RJ11 data connectors labelled ‘Link, Out/In’. These are used, along with a supplied lead, to daisy-chain the chassis together to make a 10-channel system. This lead is quite short, so dictates that the chassis are located near each other. Incidentally, the chassis do not generate much heat, meaning an air gap between rack-mounted units is unnecessary.
Staying with the link cables, a fully appointed 10-channel system will require five power supplies, each requiring a mains socket, as well as the attendant mess of wires. I feel a more elegant solution could have been to use the link lead to power other chassis in the chain. Obviously using five individual power supplies provides an element of power redundancy, but this could have been achieved by using only two supplies, plugged into the first and last chassis in the chain and using internal switching to provide a seamless changeover. Of course, a power supply to run five chassis would need to be of a higher rating than the supplied wall-warts but this could be offered by A-T as an up-sell option – something for the Mark 2 version perhaps?
A Right Pair
The front panel display and controls are very simple to use. Channel ID selection is made by the repeated pressing of a switch below the indicating display until the desired channel shows. Once selected, the channel number flashes until it is paired with the transmitter. This action is achieved by pressing the ‘Pair’ button on the chassis, followed by an identical button on the transmitter device you wish to pair it to. The display stops flashing and the corresponding pairing number also appear in the display of the transmitter. Once paired, the chassis display shows the conditions of the transmitter’s batteries and the RF signal strength from it. If un-muted, the received audio level from the transmitter is indicated as a simple traffic light LED. A further indication shows whether the chassis has been linked to another. Linking chassis will also affect the available channel pairings that can be selected.
A point to remember is that when pairing multiple transmitters, once a transmitter and receiver are paired, the former must be temporarily switched off while the pairing process is carried out on a further device. The chassis knows what devices, and thus channels, have already been paired so will only offer unpaired channels for selection.
The review system was two ATW-1311/L systems with dual belt-pack transmitters. The differences between the products in the System 10 PRO range are the combinations of handheld microphone and belt-packs (known by A-T as UniPaks). The belt-packs are solidly built items and, although I didn’t get to see the hand-held microphone, I assume it is of the same construction. It may seem a small point but I particularly liked the slide-on/slide-off battery cover. I have used other radio microphone systems, at both ends of the price range, that use hinges and clips to secure this part and it’s quite common for these to break off early in their life.
The operating frequency necessitates small antennae and this is used as an advantage in the pack design. UHF and VHF systems sometimes have trailing string-like antennae hanging from them but the System 10 PRO UniPaks feature a small stub antenna that is very robust. Connecting microphones or other devices is via a locking Hirose (HRS) connector – much better than the mini-jacks used on some other products.
The display shows the channel number but this is only briefly shown as a means, I assume, of conserving battery life and ensuring the transmitter (pictured, above) is less visible. Other controls include an audio mute switch and, internally, the previously mentioned pairing switch and audio level trim control. A handy trim tool fits inside the case to facilitate the trim adjustment.
Both the UniPak and the handheld microphone use a pair of AA batteries to power them. Although I didn’t conduct a battery life test, in one UniPak I deliberately inserted two used batteries. After 90 minutes of use, these batteries still showed no sign of expiring, so I would expect the stated seven hours battery life to be a very good estimate.
I will take as read the published audio specs of 109dB dynamic range, 20Hz to 20kHz frequency response and a harmonic distortion of less than .05% because, frankly, it is very difficult nowadays to design kit that falls short in audio quality. I was more interested in how the link performed.
I have already mentioned my crude simulation of a structured network cabling system and how the receivers communicated with the chassis while the cable length was above the recommended 100m, so I next wanted to find out how well the RF path stood up to working over more than the specified 60m maximum operating range, through some obstructions and when competing for spectrum space with other devices.
My ‘quick and dirty’ tests comprised going out for a walk, once with the receiver inside the building and a second time with it separated from the chassis and simply dangled out of the window. These tests found that in both cases I could exceed the stated 60m, although not by much. As expected, I also found that the range was reduced if my body was in the path of the link, meaning where a belt-pack is positioned on the user’s body is crucial, especially if they are working more than 50m away from the receiver.
For my RF interference test, I paired all four devices to the two chassis and set up two 2.4GHz WiFi routers and the WiFi connections on two laptops, a tablet and two mobile phones – all in close proximity to the System 10 receivers. In addition, a quick scan of internet routers picked up a further six SSIDs from some neighbouring devices. Using a WiFi scan app showed the spectrum to be fairly crowded in one section of the available bandwidth, and I could also see the spectrum being grabbed as each device was switched on or connected.
In spite of this spectrum grab, the System 10 PRO performed well, with no noticeable drop-outs of the received audio when working within the stated operational range. In practice, 60m is more than adequate to cover the majority of venues and if you need to extend further you have the 100m cabled link distance to resort to.
The supplied AT889cW tie-clip microphones performed well. These sub-miniature products sit in the upper part of the tie-clip offerings from Audio-Technica and come with a variety of fixing accessories, from standard tie-clips to button-holes. In spite of trying, under normal use, I could not get them to distort.
Overall, I was impressed with the System 10 PRO, especially the method of remote siting the receiver. Some multiple channel systems offer a software solution to setting up and monitoring the connected devices and spectrum, but I don’t really think this product is aimed at that sector of the market. The simplicity of setup and operation more than compensates for a minor lack of functionality and it would have pushed the price up anyway.
Recommended as a simple-to-use multi-user system especially for conference or presentation use, just make sure there aren’t too many wireless doorbells, baby monitors or routers around – it will make pairing-up much easier!
- Digital 24-bit/48kHz wireless operation
- Operates in 2.4GHz range
- Up to five chassis (ten receiver units)? can be linked
- Each receiver can be paired with up to? ten transmitters, 20 per chassis
- Automatic frequency selection
RRP: £759 (ATW-1311 Dual bodypack system)