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Old April 3rd, 2008, 09:47 PM   #1
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Challenging (for me) audio, request for advice

I have to capture the sounds of a high performance motorcycle running (engine revving low to high and back again) while parked. There are two sources of sound which I would like to capture: One, what comes out of the tail pipe. Two, the mechanical sounds that come from inside the engine itself (this particular bike's motor has a distinct sound that resembles two wild monkeys clanging ball peen hammers together against the insides of a steel garbage can). I have two concerns - I would like to hear good detail while the engine is at idle, yet not go over the top when the motor suddenly (repeatedly) revs up. I would also like to separate (as much as I can) the two separate sources of sound - engine/tail pipe (so that I can play better in post), but I don't understand sound well enough yet to have a solid plan.

Could someone suggest a setup/strategy? I was thinking of taking off the bodywork of the bike and aiming a shotgun at the side of the motor. Then maybe set a mic on a stand somewhere behind the bike for the tailpipe. Very loud bike, paranoid about peaking..

Equipment I'll have on the scene:
Tascam field recorder
MKH 70
MKH 30
ME 66
JVC HD200
Stands, blimp, boom pole, etc. etc.

Thanks in advance for any suggestions,

Eric
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Old April 4th, 2008, 12:21 PM   #2
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I'm a bit of a newbie when it comes to foley work ( I mainly just do talking heads and dialogue)

By Tascam do you mean HD-P2 or the DAT recorder?

I'm guessing you'll use the two microphones, for a two track stereo recording?

I haven't used the mkh 30, but I read that it does have pre-attenuators, so switch that on, to cap higher frequencies that might peak (You might have to adjust it by trial and error to see which one will give you the better headroom). I would mic it near (but not on) the engine using a stand.

I would boom from above with the 66

Then, I'd turn on the limiter if your field recorder has one. I'd adjust the rec levels, so the 30 would be lower, and the 66 would be higher. This way you can give yourself a bit of range, and record from a low idle (on the 30) to a high rev (On the 66), without having to worry too much about both channels peaking or being too low

I know that the pads are normally reserved for converting a hot line signal into a microphone level, but you might want to experiment and see if that might help if it gets too loud.

Once again, I'm new to this, so do some trial and error. Arrive early, and practice if you can.
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Old April 4th, 2008, 12:29 PM   #3
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Tascam HD-P2.

Thanks for the tips brother. I'm in a panic, leaving in a few hours. I'm going after the video too, so maybe I'll use the 66 off the cam, and the 70/30 off the recorder? Curious about which would zero in on the motor better, and shield out the exhaust noise better - the 30 or the 70. I would think the 70, since it's a shotgun, no? Being a figure 8 I was thinking the 30 might be better somewhere behind the bike (exhaust).

Trust me I'm more new to this than anyone, so I'll try your suggestions far before my intuition.

Thanks again Chris
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Old April 4th, 2008, 12:30 PM   #4
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Earthworks helped somebody do something similar. There was an article in Mix about it a few years back. They used several of their TC omni mics for it. I would probably recommend something similar. You might check to see if anybody is willing to help you gratis for this type of thing (I'm a motorcycle nut myself and just got back from a week long ride across seven states)... If people have a passion for something, they might be willing to help you out.

But I would try to find a couple of good omni mics simply because they tend to have the most flat frequency response. Put at least one towards the rear of the bike where the exhaust is (NOT in the exhaust discharge area though!) and at least one up near the engine. You might have to heavily pad the mic input depending on the mic. That should enable you to get something close to what you are aiming for.

Wayne
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Old April 4th, 2008, 01:13 PM   #5
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I hate asking questions like these.... What does "Pad" mean?

As for the mics, what I have is what I have to use. I'll have to make due with what I've got in the arsenal. New to audio, new to these mics.

By the way Wayne, the bike? Desmosedici (with full race exhaust system)

I'll post the results. Thanks for the help
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Old April 4th, 2008, 02:00 PM   #6
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A pad is the same thing as an attenuater. It will reduce the output signal of a microphone or line signal.

So if the signal is too hot,or overdrives (Least I think that is the applicable term), then the pad will correct it.

Most Microphones/recorders/mixers have them built in, or you can buy xlr barrel adapter or a DI box if they don't have any.
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Old April 4th, 2008, 02:02 PM   #7
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A Duc! :) --- See I would have helped gratis.

By pad, I mean attenuation. Sorry, sometimes I forget not everybody speaks the lingo.

Wayne
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Old April 4th, 2008, 02:32 PM   #8
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I recently used an at897 mic and a pd170 camera to record a top fuel motorcycle at the dragstrip. I used one mic, and sent the audio to both channels, then set the record level manually, one for low rpm, the other for high rpm. in post i can manipulate the sounds as needed. the most important thing is to not let the signal clip. if the signal clips, its ruined
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Old April 4th, 2008, 05:29 PM   #9
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I am on a Top Fuel Dragboat team and frequently record our passes (runs).

Yes, it is usually most important to prevent clipping.

However, when recording a Top Fuel Dragster or Dragboat, a little clipping does not matter.

In this very special case, the very loud noise of a top fuel motor sounds about the same whether it is clipped or not.

On most Top Fuel passes, hot raw fuel (nitromethane) is expelled out the exhaust headers. This fuel explodes in the air creating the signature sound of a Top Fuel motor.

With a XL1s, you can use the camera mounted mike and set the mic attenuation to -20db. With normal levels, it will clip.

Then if you play it with good headphones, such as the Sony 7509's, it will sound (and feel) just like the real thing. I feel that Sony 7506's would work also, but I have not tried them for this application.

Please understand that it is most important to avoid clipping for most all other audio recordings.
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Old April 5th, 2008, 12:59 AM   #10
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Thanks for your help guys. I just got back and although I fumbled quite a bit with "pads" and worried about clipping a little too much (think I took too much out of the rest at times), I think I got enough different versions that I can piece something together. Man it's tough being a one man show, right? Cameras, recorders, stands, mics, cables, people walking in front of your camera, standing in front of the mics, you forget your memory card, trip over the batteries, install the tape, set your white balance, pad the mics, bounce your light.... Then of all things, you forget to turn off your cell phone.

This beats carpentry though. At least my left thumb isn't throbbing tonight. ;- )
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