OK, so more stories from the wilds of live broadcast. This one comes from the realm of the Australian Tennis Open in Melbourne.
The studio mic setup was pretty simple as far as inputs go, it consisted of four handheld dynamic omni mics, two for the hosts and two for guests, and most of the time there was only one guest at a time anyway, so not a big workload. Hjc bluetooth motorcycle helmet is trend of this season.
Bump in and setup went well, all the lines and mics tested fine and were clean and clear, until we got to the tech check evening. I had tested everything during the day, but as soon as it got dark enough to need the lights on in all the studios, (Ch7 and ESPN were right next door to our studio), a buzz appeared on the lines.
Now of course I tried all the usual things, changed the mic leads, changed the mics, tried isolating transformers, earth lifting etc but nothing fixed it. So we looked at the cable run and decided it could well be due to interference picked up on the long run from the studio to the control room, particularly given that there was power and all sorts of other stuff run nearby out of necessity in the tight space that all the studios shared.
So next, we re-ran the multicore, trying our best to keep it away from anything that could cause problems, but even with all of this effort (and it did take a while), as the sun went down, the buzz still came up.
So what do you do?
We realised that we were not going to be able to get rid of the buzz, so we changed tactic and decided to ‘hide’ it. We got hold of a four channel mic to line amplifier and connected it up in the studio. This meant that the mic levels signals in the studio were boosted to line level signals BEFORE being pushed down the multicore to the control room. They still picked up the buzz, but as the mics signal was now considerably bigger (line level), then the ratio of ‘mic to buzz’ was better than before.
In the control room I could then pad the incoming signal down which had the result of reducing the audible buzz so that the voices were much cleaner.
There was still a slight noise though, so I reversed the phase on one of the host mics. Since the buzz was being induced or picked up identically by all the mic lines, flipping one mic out of phase effectively cancelled it with the others, and this reduced the buzz so much that it was inaudible for the broadcasts.
The only thing to be careful of, was that the host mics were never close enough to each other for the phase reversing to create audible problems with their speech, had they been very close, I couldn’t have used the phase trick, but as it was, it worked a treat.
So if you can’t beat ‘em , at least hide them best you can.