February 07, 2013, by Paul Watson
British RF engineer Barry Macleod has had a long and distinguished career in rock ‘n’ roll, looking after wireless systems at major international events such as Live 8 and Live Earth, as well as a plethora of BRIT Awards and MTV Awards ceremonies.
I recently spoke with him about his latest project, the touring version of Andrew Lloyd Webber’s Jesus Christ Superstar (JCS), which will hit U.S. arenas in the coming months.
Paul Watson: The JCS tour required 50 channels of wireless systems; why was that, exactly, and what was your core setup?
Barry Macleod: We had so many channels because I used 42 simultaneously and needed to also have 22 in-ear systems running all the time. The extra eight channels gave me the flexibility to slot extra stuff in when required from venue to venue. It was mainly Shure equipment — (UHF-R Series) UR1 and UR1Ms bodypack transmitters, G3 handhelds, and then Shure PSM1000 (personal monitor systems).
As video screens continue to become more prevalent in all types of productions, they also seem to be taking up more and more RF; are they becoming increasingly problematic to your workflow?
Absolutely! On JCS the video screen was producing a huge amount of RF. Because manufacturers are making these screens out of plastic so they can hang huge amounts of them, there is no screening of the power supplies and components whatsoever; we did try and work with XL Video (the video company on the tour) to try and make it better, but whatever we did never cured it.
How do you get around the problem?
We localized more antennas around the stage so that no one was more than seven or eight meters away from an antenna. It was important that none of the antennas were pointing at the screen, because they reject stuff from the back. And then I put my cunning plan into action…
...And what was that?
An idea I’d had up my sleeve for some time, actually. Using Shure Wireless Workbench and AXT600 Spectrum Manager, I effectively managed to get a scan of what the screen was doing. This allowed me to go to a venue, scan the venue, then superimpose the screen on top – that was my starting point.
From there, I used Sennheiser AC3 antenna combiners, but in quite a different fashion: I put antennas on the inputs and ran the output to the receivers, and tried to keep the gain as low as I could. I also deployed Sennheiser AB3700 antenna boosters and some Shure boosters too, which were always the last part of the chain, so any gain was put in after it had been gain-reduced by the cable length. Thankfully, it worked!
Do you have a general rule of thumb when it comes to preparing for a major show?
Well, I always say everything has to be right in the whole chain – believe it or not, a little bit of dodgy BNC cable with the pin pushed back 2 mm can be enough for the whole thing to go absolutely wrong. It’s all about attention to detail: every part of your rack and every part of what you do has to be right.
A scene from the UK/Europe production of Jesus Christ Superstar. (click to enlarge)
You play around with antenna positions to get them right for your show, then you identify the issues that are around and try to circumvent them or do something to make them less of an issue.
What is the current state of the industry in the UK, and how does it differ from the European market?
Well, for a start, the UK bases everything it does on TV channels; the area we go into is also occupied by TV broadcasters. In the U.S. and Japan, they use 6 MHz (wide) TV channels, but in Europe we are predominantly using 8 MHz (wide) channels.
In the main of Europe, we’re quite organized in that we have major TV companies that broadcast digital TV; if you get permission to start up your own TV station, you take that to a company who will then broadcast that for you for a fee.
The same happens in France and Germany, but there are a couple of countries that aren’t like that. The one that sends a shiver down the spine is always Italy. [laughs] Over there, if you start up your own TV station, you stick your transmitter on your roof and away you go, and you broadcast to a local area.
Radio mics and IEM systems in Italy always have been and always will be a nightmare as a result. Put it this way, I have scanned there and seen everything: from 530 MHz all the way up to 750 MHz, digital TV on top of digital TV on top of digital TV, and there is literally nowhere to go, spectrum-wise.
I see. I guess you must have seen some reduction in spectrum availability here in the UK, too, since the Channel 38 switchover?
Yes, that’s true, but I’ve always had this thing about putting the most amount of frequencies in the smallest possible space, so now it’s just a case of having to do that a lot more, as we’ve lost effectively 70 MHz worth of spectrum since the switchover.
Essentially, the more RF there is, the more efficient you have to try and be?
Exactly, and if you look at it, there’s more and more digital TV scattered around the place these days, so whatever we do now, it has to be squeezed into a smaller space. Every manufacturer says: “you can put this many frequencies in and you can do this and that,” but that’s based on ideal conditions and we don’t really work in ideal conditions. So what we have to do is play around and deal with it our way, building up a knowledge database through trial and error, really.
Are there any major advancements on the horizon in terms of RF technology, or anything you’d like to see change within the industry?
Everything’s progressing. If you look at digital wireless, Shure has a system out that’s particularly inexpensive and Sennheiser has a system out that is more expensive. Digital has its uses, but again, once we enter into that world, we have latency.
I’d love to be able to go digital on everything, but we’re already going through digital desks, which have latency, so until the latency becomes negligible, we’re always going to have to use the analog side of things. Even when I stand at a digital desk with a digital mic and speak into it, I can feel the delay in my in-ear monitors, so for a drummer trying to follow a click – well, you can imagine the potential issues.
You just did Robbie Williams’ new show at The O2, which was set “in the round” – does that require a different approach in terms of RF?
Yes it does. I had a chat with the monitor engineer and persuaded him that the best place for the in-ear antenna was right above the stage in the roof, and as it was they had a motion control station up there, so that’s where I put the racks. They needed someone to stay with them, so I would travel 30 meters up into the roof to go to work, and actually it worked really well; I didn’t have to use very high power and I didn’t have do anything particularly tricky.
But it’s that sort of thing that has to be considered: where do I put it? The antenna cables were 2 meters long so we could maximize the amount of RF that came out of the transmitter.
As RF engineers, that is our biggest thing: any bit of cable we put on, we get loss, even the good RG 213 cable loses power every three meters, effectively, so if you put a 10-meter cable on there, you’ve halved your power from 50 mw down to 25 mw, or 30 mw down to 15 mw. That’s why it was the best place for the antenna.
Do you ever just think “how can I make this simpler?”
Oh, all the time, but I haven’t come up with an answer yet! [laughs] In my job, I like to be able to tell people with confidence which way to go when they’re working with big systems, but you know, at the moment I’m just not sure.
There are a lot of things that are good in one respect and bad in another when you’re working in RF, and I’m still a great believer in “keep it simple, stupid” and taking it from there. But yes, maybe we can simplify the process somewhere along the line – that’d be nice, wouldn’t it? [smiles]
Paul Watson is the editor for Europe for Live Sound International and ProSoundWeb.