Car FX – part 2

Thanks to Michael for the question: “Just wanted to ask you how you found the dynamic mics handled wind and vibration noise when recording the Valiant Charger?”

I’ve never had any trouble with either wind noise or vibration using dynamic mics. Sounds too good to be true but it is – I must have recorded half a dozen cars or more & gaffer taped a dynamic to the rear bumper right by the exhaust = no problem! Gaffered a dynamic mic in the engine bay & almost always no problem, the only caveat being; beware of mounting the mic too close to the distributor – once or twice i’ve had to move the mic to get away from periodic static generated by the distributor. If you dont know what a distributor is, & presuming you know what a spark plug is; the distributor generates sequential voltage to each of the spark plugs so they fire (or zap!) in time, so if you trace the cables going from each of the spark plugs back to the round black plastic thing (the distributor) then mount your mic nowhere near it. It isnt a noise you hear in the engine bay, more a signal caused by interference in your mics or cables..

Re wind noise: I wrap the dynamic mics in what i think is called ‘polar fleece’ – its a material a bit like what sweatshirts are made out of, although slightly thicker… You can buy lightweight jackets made of it, that will keep you warm in a very cold wind. Wrap & then gaffer tape the mics tightly with this… I’ve never had a problem with wind buffets. I think this is due to a few factors: dynamic mics are way less sensitive to wind than shotgun mics. Consider how much trouble you have to go to, to protect a shotgun mic from even the wind generated by slowly moving the mic. Compare that with the pop shield involved in someone basically shouting at a dynamic mic… the shotgun mic is floated to avoid vibrational movement, then protected by a Rycote cage (light foam) then wrapped in the inner softie and then the exterior fluffy… a pop shield is like 2 layers of nylon stocking….
You definitely need to protect the mic but remember dynamic mics are placed one cm away from a drum skin, while someone smacks them with sticks!

Vibration: no problem! I’ve always gaffer taped the mic directly to the rear bumper bar. Depending on how far out the exhaust protudes; with the Valiant I could position the mic vertically as the end of the exhaust was directly below the bumper. On another car I recorded this week the exhaust was like 1 foot closer to the engine than the bumper, so I angled the mic so it was pointed at the exhaust.
The engine mic I have always partly gaffer taped & partly wedged it into whatever space there is in the engine bay. I would offer practical advice but every time is different. That Valiant was different to the lovely old 4 cylinder Singer Vogue I also recorded, which was also different to the gang car; a Falcon big block V8, which was the loudest V8 I have ever heard!!!

And that is my final word of advice: be ready to pad the level of the dynamic mics down prior to your mic preamps. Some cars are very LOUD! I remember reading about people recording Formula 1 race cars & they had Shure SM58 mics mounted by the exhaust & in the engine bay. But they discovered that the incredible SPL was such that these dynamic mics were generating like 3 or 4volts rather than the millivolts that the mic preamps were expecting. So they had to use lots of inline mic pads to reduce the voltage down to a level that they could cleanly record. When I was recording the Valiant the Fostex PD6 kept throwing up ‘clip detected’ errors oncreen, which i had to manually clear before I could see the actual level. After I turned down the record levels such that they were no where near hitting 0dB & I was still getting ‘clip detected’ errors I realised the mics were clipping the mic preamp inputs, so I switched in the inline pads that the PD6 has (pre-mic preamp) and no more problems. I should really get a few 6dB and 12dB XLR inline pads for emergencies & I sure as hell will before ever recording a seriously loud vehicle. They could easily make the difference between a totally distorted unuseable recording & a multi-track recording you can be proud of!

Also a tip from people micing up drum kits, use your ear as your guide. Literally! For example in the engine bay, open the bonnet & get someone to rev the engine & use your ears to localise where the best sound is. Too close to the fan belt & you’ll just get belt whine. Does it have a turbo? How about the sound of the air intake? Whats the most interesting sound you hear? Put your ear right in there & locate a perspective you like, then gaffer tap your mic there! Remember that dynamic mics only see/hear a short distance…

I just got home so tomorrow & over the weekend will load up all my recordings & quickly make notes/tag info & metadata & embed photos with each recording while all the memories are still fresh. Theres nothing worse than revisiting a recording a few months later & trying to work out where it was recorded by a few vague verbal comments… Right now my psyche is still back on the beautiful East Cape, but even the drive through rush hour traffic getting back into town has started to erode that….

ps heres a photo of the two mics I used, still wrapped as I used them… in fact I leave them wrapped like this until i need them for something else…. Excuse the gaffer tape mess, I literally pulled them off the car & threw them in a pelican case…

A final warning: you must be careful leaving any loose wires hanging anywhere on the car – i’d hate to see what would happen if a mic cable got tangled with the fan belt! But also be very careful with routing cables back to your recorder. I usually just put them through a window that is open enough to allow it, but again you end up gaffer taping loose cable to the car body & be very very very careful removing that tape! The owner of that car will not be your friend if you remove some of their paintwork when you remove your cables!!!

6 Responses to Car FX – part 2

  1. Andrew says:

    Thanks for sharing this. Very insightful!

  2. Benoit Tigeot says:

    Thanks a lot for this article.

    I’m waiting for your sound/pictures/note for your previous recordings.

    Cheers

    • admin says:

      Cant really post them until the film is done… & we dont start it until mid August….
      sorry!

  3. T says:

    Just saw this post. Wondering which dynamic mics you used! Thanks!

    • tim says:

      The dynamic mics I used just tended to be the ones I owned – an EV RE27 and an AKG mic (can’t remember the model – will have a look when at studio)

  4. T says:

    THinking about using an SM58 myself on my next gig record exhausts….

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