Best audio for airshows?

[George Ellis]

I started this thread as a breakout of a question in one of the HDV sections. What would you folks recommend for audio capture at an airshow?

What I threw out was that I hated most footage I have seen because it is mono and does not capture the motion across the field including high speed passes. It is almost always AGL (auto gain leveled), so losses doppler and speed. It is almost always buried in music in post.

I was thinking a stationary stereo pair would be kick butt. Putting attenuators on might be necessary (Harriers, high speed passes could overvolt some situations). There was also the rumour that powered mics were more easily damaged by loud jets.

What is the opinion of our fellow learned individuals?

[Seth Bloombaum]

I'd have to agree that this is a natural for a fixed stereo mic or array. I think it would be best on its own stand, not moving with the camera, so that the stereo image is constant no matter what the camera is doing (like almost all stereo micing situations). And of course in my not so humble opinion AGC is most unwelcome in almost any situation.

X/Y, M-S, or ORTF would seem to be the stereo arrays of choice. Usually, you'd pick X/Y or M-S if mono downmix during playback is of concern, but you'd probably not notice any downmix issues with this content (big whooshes, swooshes, noise and rumble), so I'd try ORTF for maximum imaging (but then I'm pretty biased towards ORTF).

Overload of the mics - not a clue without some info on the sound pressure level typical of these shows. Could be a serious issue; once the diaphram of the typical condensor mic is rattling it's all over for sound collection, and may be permanently damaged, depending. How about dynamic cardoid or supercardoid mics, eg. Sennheiser MD421 (cardoid) or MD441 (super)?

ORTF = a stereo array of 2 cardoid (typically small diaphram condensor) mics at an angle of about 110 degrees with capsules about 7 inches apart. Both these Senn mics are big compared to to typical small condensors, so, beefy stereo bar and stand would be needed.

[Bill Davis]

That approach might work great - but positioning could be critical.

Unless you can get physical distance from the spectator crowd, I'd be concerned that the couple near me in the crowd - arguing about his mother in law coming to live with them - might mess up the whole recording.

And as a matter of course, I always prefer to record in mono rather than stereo since it's less prone to multipath/phase issues in post.

The dopler effect shouldn't suffer since it's part of the sound quality being recorded and wouldn't change whether you're redording in mono or stereo.

Personally, I think I'd try a single large diaphram dynamic mic (perhaps something like a Sennheiser MD-421 with an appropriate pad to keep the level in check - mounted on a really tall stand to ISO the flyby.

Then simply pan the resulting track across the stereo field during post to follow the plane .

It'd TRY that. But be willing to try the stereo approach as well to see if it's superior.

The key to my feeling comfortable with this would be considering how much of my potential audience would be likely to play back the recording on a real stereo sound system.

Collapsing a stereo signal down to mono for the HUGE numbers of legacy mono TV sets can be a challenge if the original recording is stereo.

Particularly a signal that's both moving rapidly and potentially bouncing off buildings and such, creating a pretty complex multi-path range of first, second, and third order delays.

Intersting challenge.

Whatever you decide to do, drop back and let us know how things go.

[Jim Boda]

I would lean towards the MONO recording and pan it in post. Because of the speed of sound, there would be a slight delay in the real stereo recording. It would be more dramatic to match the highspeed visual with the sound.

A large diaphragm mic would be good for that incredible low frequency stuff.

Getting the level set properly is critical. I would rely on a good limiter until that level get's dialed in.

[Steve House]

I might add too that if you haven't selected the mic(s) yet, choosing ones that have an switchable internal or screwon pad might help avoid overload and clipping. Limiters are also important but they come later in the audio chain and if clipping happens between the mic capsule itself and its internal electronics there's nothing a limiter later on will do to help it. Schoeps for expensive mics and Octava's for cheap ones both have a pad that you install by unscrewing the capsule, fastening the pad on the end of the body, and replacing the capsule on top of it.

[Mike Gorski]

Good suggestions. Being a new comer to the world of audio, its defnitely my weakest area of knowledge. Does anyone know of some good links or book suggestions to give me more basics on today's modern audio terms/techniques. I know theres a lot but I need to build a better basic base of knowledge. Its a little off topic but I am too interested in shooting aviation and getting great audio from a large air show such as Sun N Fun. Thanks for the imput!

[Doug Lange]

If you put the mics on a boom 15 ft off the ground, there wouldn't be as much crowd noise. This is the cheap route, but you could buy an extra boom arm and attach it to your boom to give you more height. Use a sandbag if it gets to be unstable at that height.

This is a minor detail to consider...
With the jets flying mostly overhead, wouldn't pointing the mics up in an ORTF pattern give the best results? If most of the action is at about 1-2 o'clock, point the mics at about 1:30.