Expert Witness: Joe Mitchell

Sound Hire founder Joe Mitchell on what to look out for when sourcing a new piece of wireless kit.

I saw an old newsreel just before the general election this year, showing the presenter holding a mic and trailing a cable around the studio. It made me think how our world has changed.

My family has a background of acting in professional as well as amateur theatre productions, but I always preferred the technical side. I first used wireless microphones on a production of Oliver in 1985 – I only used two and had to change the batteries at the interval. Back then you couldn’t rack-mount the receivers because to get up to six – as a maximum – operating together you had to spread the receivers around the mixer, keeping each about half a metre apart.

By the mid to late ’90s you could get a reasonable number of wireless microphone systems operating together, and you could also rack-mount the receivers together without fear of them interfering with each other.
These days you can operate a good number of wireless microphone systems together. Bands can have wireless freedom for instruments and vocals, and theatres can double- or triple-mic their actors.

Frequency-wise UHF is where the professional systems are, and that’s where we’d like them to stay please, Ofcom.

There are several new systems being offered on higher frequencies such as licence-free 2.4GHz, however I really don’t see any serious user considering these. Firstly, these frequencies are shared with Bluetooth devices, smartphones and WiFi just for starters. 2.4GHz and 5GHz devices are licence-free in most parts of the world but if the train has no seats or standing room left, it’s a bit pointless getting on board.

We’ve now moved from Channel 69, which was right at the top of the TV band we all share, down the road to Channel 38, and like a new home this has advantages and disadvantages. If we look at the mid-priced wireless microphone systems, you could get 14-16 operating together on Channel 69 alone but that has been reduced to 8-12 on Channel 38. We are now operating in the middle of the TV bands, so we have to be much more selective about the systems we buy and use.

If you require 12-plus wireless microphone systems to operate together, one solution is to use some of the latest wide-band wireless microphone systems covering up to 75MHz of bandwidth. Some even offer 150+MHz bandwidth. There is one manufacturer that now claims one of its systems covers around 400MHz of the UHF spectrum. This being the case then I hope all the major manufacturers follow on.

Digging Digital

Digital is the way forward, the main reason being that mobile phone companies (and others) want more spectrum and they have the money to buy it. Let’s face it; we all use their technology and want better coverage. Mobile phone operators have bought most of the 800MHz band and it looks like they’ll get the 700MHz band in just a few years time, so we need more wireless microphones to operate in a smaller part of the spectrum. Digital systems can do this, and they can be encrypted which can come in handy if you do conference work and the client doesn’t want what’s being said to be broadcast outside the room. Digital systems also don’t use compander circuits, which analogue systems use to reduce noise.

There was a time when adverts for wireless microphones claimed them to be as good or better than a cabled microphone. They never were, and possibly never will be. They are more useful than their cabled cousins, and they allow total freedom of movement, but they do have some issues – the compander circuits of analogue systems differ considerably from one manufacturer to another.

One of the popular theatre system manufacturers’ companders is truly awful in my personal opinion. If you have good ears, you can hear all compander circuits; even the best is only as good as a mid-priced compressor. Digital systems change the sound slightly, and use limited data transmission rates. It’s a bit like comparing a CD to a good MP3 recording; the MP3 is acceptable to most, but not 100%.

Personal Choices

My favourite two analogue systems are AKG’s WMS470 (I’d have chosen the WMS4500 if it was available on Channel 38) and Sennheiser’s ew500.

Sennheiser ew500 systems are excellent all round – probably the best value analogue systems on the market at this time. I’ve chosen the ew500 as it has the most features and isn’t that much more expensive than the ew300 systems. These Sennheiser systems also tune over a wider frequency range than the AKG WMS470 systems.

I really like the AKG DMS800 systems due to a very wide frequency tuning range (150MHz) and features such as DBX compression being available. These are good, solid, well-made systems offering great performance, and these latest systems, which have only just come to the market off the back of the very successful DMS700 systems, now offer interchangeable handheld microphone capsules.

My final choice is the Shure QLX-D range. Shure has always been known for its handheld wired microphones, but in the past I wasn’t really a fan of its wireless offering. That’s all changed now. The Shure systems cover only half the frequency bandwidth of the AKG systems and have enormous receiver antenna, however the systems’ performance can only be described as excellent whichever way you look at it.

Joe Mitchell is founder and owner of Yorkshire-based Sound Hire, a specialist in the hire, sale and installation of radio/wireless microphone systems for applications including theatres, conferences and churches.