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Wireless mayhemNot long ago I took my annual trip to a local special school, to do a general routing and health check on their PA system. This is something I have been doing for years despite my business not really being focussed on installation or maintenance. However it was always a regular gig around which was well appreciated during the earlier (marginally leaner) days of my production career.


Now the interesting thing about special schools is that everything has to be super safe and secure. You sign into the building after walking through a couple of sets of doors, all remotely opened by reception staff. Door handles are all at a high level and even hot tap handles are removable, each staff member having one hanging from their belt. Now to suggest that this is reminiscent of a certain Patrick McGoohan TV series would be unfair as it's a lovely place. However you do see the occasional student attempt an unauthorised egress, thankfully always foiled by a metaphorical orb as in the show. To be fair I've never seen such a happy school, staff and students, but I think the escape attempts are something of a game, keeping the adults on their toes.


Right back on track now...the point of this rambling about 1960's TV shows was to focus our attention on the potential dangers of cabling that in a studio or on stage we might take for granted as a low level hazard. In a special school with a class of 15 nine year olds charging around the hall for gym or drama class one cannot risk an entanglement of the feet and subsequent launch of a child. Insert vision of a trebuchet in action here. On a more consequential path a child may get an unruly XLR cable wrapped around their neck. So any microphones that are used are required to be wireless, negating that risk.

So what solution do we have in this system? Well, a lockable rack cabinet with rackmount mixer inside. The main “FOH” speaker system comprises a pair of Bose cabs mounted high on the wall flanking a projector screen. Feeds to these are run into conduit to keep safe tiny hands. Long story short, there are a number of audio and video inputs and so on but the key thing I wanted to mention here is the radio mics.


Now the school had already tried the expensive options, a nice Sennheiser EW series but somehow the packs and handhelds would always be projected across the room, hidden in a sink or some other fate not befitting of high-end german radio mics. Plus I dread to think what happened to all the mini antennae that vanished.


So what was the solution? Cheap mics...they are tough enough, and a damn sight lighter. Thinking in terms of Newtonian physics, a cheap Sennheiser Freeport (with half the mass of perviously mentioned nice mic) is launched by a student. It is travelling at 10m/s towards the wall, eagerly watching parent at the nativity play or even the head of the...well the head of the Head.


Momentum = Mass x Velocity



Let me tell you the cheap mic grills don't seem to get half as dented as the more expensive handhelds and the bruising on the not so quick footed members of staff must logically be less. Joking aside, the lighter mics do seem to be less of a hazard when dropped or thrown. Finally the great thing about them is that they are easily replaced. Purchasing a whole system can be comparable price to a repair job or a spare part replacement. Yes the odd battery cover gets cracked but since we are looking at replacing the mics every three years or so the lower cost is easily offset.


Ok so how does this relate to the professional world? Well, radio mics can have great application in the corporate world for similar reasons. You can set a level and then let the user control the mic by simply switching on and off at the mic/transmitter pack. Plus all those litigious business executives that one might have in your conference centre will have a hard time suing for tripping over an XLR cable that is not there.


However I wanted to finish off by looking at the use of wireless systems that I deal with when I mix FOH for a couple of touring bands.



In-ears are bloody awesome. Combine them with a personal mix system or app that can connect to a digital console and your artists will stop that “up a bit, down a bit, up a bit” nonsense. They can have exactly what they think they you should be able to tweak from the FOH or monitor-world. Incidentally one band I tour with has three IEM feeds for three members, two of whom (drums and bass) are simply on wired headphones from an amp with the singer donning radio in-ears.



A ramble on wireless systems.

One of the other bands for which I mix FOH (and often also monitors) requires around 11 radio channels. I'm not going to go into the issues of using wedges and roaming musicians on radio systems. Suffice to say don't put your instrument stand next to a floor wedge when it's on a radio pack. However I will raise some of the issues I encounter on these gigs.


  1. A headset mic (even a top end one), will never sound as wholesome as a vocal up on an SM58, at least not through a PA. Yes it might be 'better quality' in some ways but not necessarily as punchy in the low mids etc.
  2. Of course we need to consider budgets. These things are not cheap and they chew through batteries like a beaver in a hard hat. Headsets are delicate things to say the least and if you are using the in-house radio systems as we sometimes do, you need to make sure you have every possible adaptor on hand as there are at least three different standard input sockets.
  3. Finally some issues with 2.4 GHz systems. So these have become popular in recent years and are pretty reliable and simple for the most-part. However you do need to watch out for a few issues. They are often not considered as part of the wireless plan at festivals. They work well in areas with no walls and very little other WiFi frequency traffic. This can glean certain unexpected results, for example, I had a guitar from a neighbouring stage pop up into a soundcheck at Glastonbury Festival last year. Granted it was a beautiful sounding guitar and nicely played. I'm just glad it didn't jump in during the set. Of course this is not an issue with the next generation of 2.4 GHz systems but the basic 16 channel beasties aren't clever enough to ignore Dave the phantom guitarist in the next field over.

Now here comes the kicker. I was mixing a show with four or five of these 2.4 GHz systems at an indoor festival a few months back. Soundcheck was fine and the systems were working great. I usually scout around the available channels too to make sure they are pretty clear, which they were. Now as the audience started to build during the first 10 mins of the set I started to notice the reception of the furthest instruments from the receivers dropping out. Again the older digital systems aren't super clever and unlike an analog system they just cut out if signal drops below a certain level rather than introducing extra noise. It's not like you can just twiddle the squelch either, these things are pretty much either on or off. Thankfully frequency shifting and handshaking systems are being implemented in the 2.4 GHz band now.


So why did this interference pop up? Well I can only imagine from the scores of smatphones wielded by the audience that they were all trying to connect to the venue's Wifi, each other, or in one case, I suspect Sputnik.


So to sum up, what does the future hold for wireless mics? Well the use of some frequencies for 4G is going to cause a knock-on effect, there is a metric tonne of info about that from Shure and other manufacturers on their websites if you are interested. We already lost some frequencies not so long ago to Digital TV (if I remember correctly) so use of multiple systems in theatre and music is gradually getting a little tougher. However I see a bright future for wireless systems, not LiFi (though that's a possibility) but more in terms of handshaking systems in the WiFi frequency. We might even see implementation of the next generation of smartphones as affordable transmitter/IEM systems at some point soon. So lots to look forward to but until then enjoy the wonderfully stressful world of wireless.

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