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Old June 20th, 2006, 05:35 PM   #1
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How to mic an engine of a moving car?

I'm trying to mic an engine of a moving car as it shifts up to top gear. What the client wants is to have the engine sound captured as he reaches top speed (> 100 mph) while I am video recording various dials, tach and speedometer.

For better or for worse (probably worse), I taped my AT-897 to the plastic computer case inside the engine compartment and ran it into an iRiver. We did several runs and got beautiful sound. The mic was hot but I could still hold it in my hand. The mic is surrounded by lots of air space and does not come close to the engine.

I realize that oil and other nasty stuff is flying around inside so I'm hoping there is a way to get good sound without exposing the mic to the bad stuff. I have the Giant Squid mic that I may consider using next as a sacrificial mic.

I'm also wondering if the sound pressure levels are too high for the mic. The client mentioned that during dyno testing, the engine sound was earplug loud. But that was in an enclosed space. Listening to it from inside the car with the windows rolled down, it seemed like the mic should be able to handle it. Its maximum input sound level is rated at 115 dB.

The total time the mic was in the engine compartment was about 10 minutes and the car is a 2006 Honda Civic.
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Old June 20th, 2006, 07:43 PM   #2
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i think your on the right track, your not using an overly expensive mic like a b6 or a cos-11.

i think you should just add one of the rycote cover-up thingies to protect the mic a little bit.

you could add a variable pad to the mic and try different amounts like -10, -20, -30 ad see if you can hear any real difference.

if this guy is doing major mechanical modifications to the cars i'm sure he could easily run an xlr cable for you through the firewall so you could run the mic into a camera or recorder inside the car and be able to hear the sound your self.

plus then you could change the pad settings much more easily.

matthew
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Old June 20th, 2006, 10:08 PM   #3
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Are you after actual "engine"noise? (mechanical sounds)or representative sound(exhaust)?I have recorded a fair bit of sounds of vintage muscle cars eg. Hemi Cudas,Yanko Camaros,etc. and the combination sound of exhaust and a little mechanical mixed certainly is representative of engine horsepower and rpm.What is the actual purpose of the recording?
Check out the sounds of the cars at this site.http://www.legendarymotorcar.com/home.htm
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Old June 20th, 2006, 10:24 PM   #4
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Any pads to recommend?

Quote:
Originally Posted by Matthew de Jongh
i think you should just add one of the rycote cover-up thingies to protect the mic a little bit.

you could add a variable pad to the mic and try different amounts like -10, -20, -30 ad see if you can hear any real difference.

if this guy is doing major mechanical modifications to the cars i'm sure he could easily run an xlr cable for you through the firewall so you could run the mic into a camera or recorder inside the car and be able to hear the sound your self.

plus then you could change the pad settings much more easily.
Do you think any foam windscreen will do? I took it off since I didn't know if the hostile environment would do something to the delicate material.

I like the idea of the variable pad; any that you recommend?

You gave me the idea to hook up the sound to the camcorder - but instead of a mic cable, I'll try my Sennheiser SKP 100 G2 plug-on transmitter to give me the live feed. It will be easier than trying to synch up the iRiver audio.
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Old June 20th, 2006, 10:46 PM   #5
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Looking for less muffled noise

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Originally Posted by Jack Smith
Are you after actual "engine"noise? (mechanical sounds)or representative sound(exhaust)? I have recorded a fair bit of sounds of vintage muscle cars eg. Hemi Cudas,Yanko Camaros,etc. and the combination sound of exhaust and a little mechanical mixed certainly is representative of engine horsepower and rpm. What is the actual purpose of the recording?
Check out the sounds of the cars at this site.http://www.legendarymotorcar.com/home.htm
The purpose of the recording is to sell sizzle. These videos will be heading for a website for now, perhaps a DVD later on, to advertise the kit he is selling. Using the muffled audio inside the passenger compartment takes the edge off 400 HP at the wheels.

How do you recommend recording the exhaust? I'm concerned about securing it without damaging the car or the mic. I will probably want to use the Sennheiser SKP 100 G2 plug-on transmitter if this is possible.

I tried most all of your links but could not find any sounds. I must be missing something obvious.
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Old June 20th, 2006, 11:49 PM   #6
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shouldn't you try and record from several areas and then mix them down? from the rear you need tires grabbing and tailpipe rumble ,from the inside you need the stick shift click and from the front you need the whine as the engine revs. however at some point the engine compartment pressure will be to great and the mic will no longer get a "clean sound" so under the hood can be recorded in park with hood up and foot on gas??
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Old June 21st, 2006, 12:04 AM   #7
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Yes, I should get those too

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Originally Posted by Craig Chartier
shouldn't you try and record from several areas and then mix them down? from the rear you need tires grabbing and tailpipe rumble, from the inside you need the stick shift click and from the front you need the whine as the engine revs. however at some point the engine compartment pressure will be to great and the mic will no longer get a "clean sound" so under the hood can be recorded in park with hood up and foot on gas??
Getting the stick shift will be no problem but securing a shotgun outside the car that jerks pretty hard with each gear is what has me worried.
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Old June 21st, 2006, 04:21 AM   #8
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Robust dynamics

At these sound levels, especially inside the engine compartment, wouldn't a dynamic SM58-ish mike be an option? These mikes will be able to withstand a lot of abuse. They're cheaper too.

Dirk
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Old June 21st, 2006, 10:23 AM   #9
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Good idea - I do have an SM58

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Originally Posted by Dirk Boswinkel
At these sound levels, especially inside the engine compartment, wouldn't a dynamic SM58-ish mike be an option? These mikes will be able to withstand a lot of abuse. They're cheaper too.
Thanks for the suggestion. I do have a wireless SM58. But once again, mounting outside to get exhaust or tires is my big issue.
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Old June 21st, 2006, 10:28 AM   #10
 
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An SM57 mounted to the body near the tires should be about what you want, and it's a cheapie. Durable as anything, you should be able to get a variety of sounds just on placement.
Recently put a wireless lav inside a motorcycle rim and moved the bike at medium speed to get the sound of the road/tire/hub sound, it came off quite nicely until the bike hit around 40 mph and tossed the transmitter off.
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Old June 21st, 2006, 10:39 AM   #11
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I'll look under the body

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Originally Posted by Douglas Spotted Eagle
An SM57 mounted to the body near the tires should be about what you want, and it's a cheapie. Durable as anything, you should be able to get a variety of sounds just on placement.
Recently put a wireless lav inside a motorcycle rim and moved the bike at medium speed to get the sound of the road/tire/hub sound, it came off quite nicely until the bike hit around 40 mph and tossed the transmitter off.
Thanks for the info. I think I'll have them put the car on the lift and I'll look to mount the mic underneath where it's still exposed to the outside sound but can be more securely mounted than hanging off the side or back of the body.
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Old June 21st, 2006, 11:32 AM   #12
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One tip I have for you is put you equipment in a ziplock baggie, clip cornor for the cord to feed the mic out when you put it up under the car. I would look in the bumper area on alot of the newer cars is areas they have the space and coverage needed. Good Luck!
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Old June 21st, 2006, 11:52 AM   #13
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Omni Directional mics have the best freq. response, and dynamic range. Directional (ShootGuns) are the worst and will distort some of the freq. ranges.

Think of the car as a philharmonic orchestra, you get different sound in each area. Monitor the sound from different areas in and out the car, let the "Mechanic" be the conductor, Give him good headphones and he will decide what is the sound he likes best.
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Old June 21st, 2006, 12:05 PM   #14
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Thanks for the tip

Quote:
Originally Posted by Angela Frasure
One tip I have for you is put you equipment in a ziplock baggie, clip cornor for the cord to feed the mic out when you put it up under the car. I would look in the bumper area on alot of the newer cars is areas they have the space and coverage needed. Good Luck!
I will have to experiment with different locations. Wind noise will definitely vary according to location and the kind of mic.
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Old June 21st, 2006, 12:08 PM   #15
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My Giant Squid is an omni

Quote:
Originally Posted by Danny Natovich
Omni Directional mics have the best freq. response, and dynamic range. Directional (ShootGuns) are the worst and will distort some of the freq. ranges.

Think of the car as a philharmonic orchestra, you get different sound in each area. Monitor the sound from different areas in and out the car, let the "Mechanic" be the conductor, Give him good headphones and he will decide what is the sound he likes best.
I just heard from Darren Nemeth of Giant Squid microphones and he said the mics are rated up to 110 dB, so I'll try mounting that in different places. I should have an easier time of it than the bigger ones.
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