Recording Engine/Ambient Noise

R

rick3000

Member
Hi,
I am doing a short film which involves a driving scene. The car is a mid engine, so my idea was to put a microphone in the trunk so it could pick up the exhaust and the engine.
Should I use a hypercardioid, shotgun, or omni microphone?
For general ambient noise (i.e. - car engine, water, footsteps, etc.) and music is a hypercardioid or shotgun going to be better?

I've been stuck between buying the NGT2 or NT3 first, so this may help me decide. My budget is about $250 for one microphone, can you suggest something better?
Thanks! :dankk2:
 
The way you mic and record a vehicle will depend largely on the way it was shot. I doubt that placing a mic inside the trunk will give optimal results, unless the on-screen action is taking place inside the trunk.

For general-purpose coverage, I like to focus on three different perspectives: interior, stationary exterior (for starts, stops and passbys), and "chase" exterior (in which the mics stay a fixed distance from the car during the maneuvers). Interiors benefit greatly from surround tracking, although you should be careful to isolate extrenuous noises (jingling keys, driver cloth moves, etc.) To save time during stationary exteriors and increase editorial flexibility, I often simultaneously track both a medium perspective stereo pair and a close-up mic.

"Chase" mic'ing is usually the trickey one, though. One quick and easy technique is to simply stick a shotgun mic (in a zepplin and windjammer) out the window, cue it towards the tires, and drive in a very low gear (maximum RPM, minimum wind) with a 90Hz low-cut. If I need a bigger, more intense sound I'll use ultra-clamps and gaffer tape to close-mic the grille (Shure SM-58) and the tail pipe (Electrovoice 635). To add a bit more space to the tracks I use a second 635 taped to the door panel (to pick up the tire contact), often in addition to a shotgun out the window.

Obviously, one mic isn't going to work for all the tasks. I love the 635's for their ability to shrug off wind while taking a real pounding, but most of the effects I record are mic'd with a Sennheiser MKH416. A good short shotgun is probably the best place to start for the effects you describe, although cardioid mics are better suited to music recording. Its also worth pointing out that you'll also need a good shock-mount and wind protection. I'm not certain you'll be able to cover all the bases with a $250 budget, but I'm sure other forum posters can offer you sage advice on that score.
 
As stated coverage really depends on what your doing and what you need. General moving coverage would include the by's (be sure to get one with a horn for that classic doppler sound). And interiors (pretty boring, but nesc.). The traveling with the car setup usually has a mic on the rear bumper with LOTS of foam for wind protection to get that low exhaust sound (a SM58 works quite well). One under the hood, or at the grill. You have to poke around to find a good sounding location. Again a dynamic is often a good choice because of the volume and because they tend to be less likley to pick up electrical noise from the ignition system.

AND BIG WARNING - the "high tension" side of the ignition system (spark plug wires etc) are carrying many THOUSANDS of volts. That kind of voltage can jump through space and can cause induction voltages in things like say mic cables. DO NOT have your mic cable anywhere near the sparkplug wires or you run a real risk of frying your recorder. Mic ins don't like high voltage.

Also a mic in the wheel well can give you some nice tire sounds, if your doing peelouts etc.

It is also good to find a place far from people with a hill. If the moter isn't straining a bit you won't get much. Also it's a lot easier to "peel out" going up hill and skid to a stop going down hill.

Last BE CAREFUL if your doing skiddy kinds of stuff. It's fun and it sounds great but it's mostly illegal and you (or the driver) can get badly hurt if your not careful.
 
The SM58 is a cardioid dynamic. And NO you don't want it as close as possible, the heat will destroy the mic. I usually mount the mic on the bumper above the exhaust, not super close, put it where is sounds the way you like.

For By's standing in one place and following the car with a shotgun works pretty well. Your biggest problem is that at any speed the by is too fast, so panning with the car "stretches" out the by a bit.
 
I prefer using dynamics for bumper-mounted recording. They'll take a lot more punishment than comparatively fragile condensor and electret mics. Although I'm partial to the 635, an SM58 would also work well near the exhaust. Avoid placing the mic too close to the exhaust, or directly behind it since the blast of exhaust will tend to gust the mic. The exact placement of the mics will depend on the exact sound you're after, but as a general rule you should go for at least a couple different angles.

If you're unable to book a private track, be sure to use a stretch of road that's fairly isolated and low-traffic. Wear a traffic safety vest, and never perform any maneuvers without a clear view in both directions.
 
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