Recording an engine

Posted: Thu Nov 09, 2006 5:11 pm

I'm pretty new to audio work and could use some pointers. Not even sure this is the best forum for this, but "live sound" seemed to be the closest thing to what I need to do....

I will be recording engine sounds. Mostly diesel, but some gasoline. Mostly larger farm equipment, but not always. My two basic questions are:

1) what would be the best type of mic for this work?

2) what would be the best placement for the mic? A lot of the sound will be coming from the exhaust, but not all. Most of these big engines make quite a bit of sound and move a lot of air (radiator fan) however, I'm not wanting exhaust sounds or blowing air sounds. I just want the sound of the engine. I'll be recording startup, idle, loaded, and shutdown. Some of it can also be a rather high frequency, like the sound of the turbo spinning up and winding down at power off.

Any advice will be greatly appreciated!

-Farren

Posted: Thu Nov 09, 2006 11:59 pm

Record samples of it from everywhere, metaphorically speaking... Run circles around the truck/whatever with the record button pressed.

You'll find a sweet spot.

I'd use a cardiod dynamic unless ambient noise is an issue, then tighten up the polarity.

Sounds like time for some experimentation.

Have fun!

Cheers,
-Ryan-

Posted: Fri Nov 10, 2006 3:24 am

Try putting a wireless lavalier microphone under the hood? You will get all the engine sound you want.

What's the difference between an elephant fart and a barroom??

Well a barroom is just a barroom but an elephant fart is a BARROOM!

In the barroom
Ms. Remy Ann David

Posted: Fri Nov 10, 2006 11:45 am

I'm interested in this sort of recording as well, for samples and such.

What sort of microphones are those we always see on the weather channel during hurricanes and storms that have the rodent wrapped around them? I'm guessing some sort of hypercardioid with a wind sock straight from a mink farm in the far reaches of the Cyberia.

Posted: Fri Nov 10, 2006 4:28 pm

What? A barroom or an elephant fart??

Most of those microphones are omnidirectional dynamic microphones such as the venerable Electro-Voice 635. Those are somewhat bandwidth limited as well, since you don't need ultimate fidelity in a hurricane while trying to talk. They have no extraneous openings in the sides of the barrel to let wind blow through.

Condenser microphones are more highly susceptible to wetness and humidity problems. And I'm talking electret here which are permanently polarized. As opposed to a true condenser microphone that requires an additional 48 volts to polarize the capsule. Forget about that on foggy days! You can make a U87 fadeout in the studio if you are using no pop filter, working it too close and breathing all over it a lot. Really.

Cardioid microphones with their open sided acoustical labyrinths are much more susceptible to wind noise and "Plosives" or pops. Of course if you have a long shotgun microphone with a plastic blimp covered in faux fur, you could deal with up to 30 miles an hour winds with just a little high pass filtering but no hurricane.

Personally, I would rather have a blue Hawaiian
Ms. Remy Ann David

Posted: Fri Nov 10, 2006 7:08 pm

farren wrote:

I'm pretty new to audio work and could use some pointers. Not even sure this is the best forum for this, but "live sound" seemed to be the closest thing to what I need to do....

I will be recording engine sounds. Mostly diesel, but some gasoline. Mostly larger farm equipment, but not always. My two basic questions are:

1) what would be the best type of mic for this work?

2) what would be the best placement for the mic? A lot of the sound will be coming from the exhaust, but not all. Most of these big engines make quite a bit of sound and move a lot of air (radiator fan) however, I'm not wanting exhaust sounds or blowing air sounds. I just want the sound of the engine. I'll be recording startup, idle, loaded, and shutdown. Some of it can also be a rather high frequency, like the sound of the turbo spinning up and winding down at power off.

Any advice will be greatly appreciated!

-Farren

Do a google. There are companies in the trucking business, that have developed mic/sensors for engine parts. A computer samples the noises and then is able to determine if a part is functioning correctly. My friend developed a comparable system for tires. It alarms the driver when the tire will go, long before it happens. Pretty cool.

That said, it seems to me that you would need to buy a decent set of field recording mics, with a boom arm, wind sock, and field recorder (flash, HD, etc). This way you can maybe get some other local work with TV stations, advertising houses, etc developing a sound effects library or freelancing. I have another friend that made money recording NASCAR races like this.

Posted: Fri Nov 10, 2006 7:11 pm

farren wrote:

I'm pretty new to audio work and could use some pointers. Not even sure this is the best forum for this, but "live sound" seemed to be the closest thing to what I need to do....

I will be recording engine sounds. Mostly diesel, but some gasoline. Mostly larger farm equipment, but not always. My two basic questions are:

1) what would be the best type of mic for this work?

2) what would be the best placement for the mic? A lot of the sound will be coming from the exhaust, but not all. Most of these big engines make quite a bit of sound and move a lot of air (radiator fan) however, I'm not wanting exhaust sounds or blowing air sounds. I just want the sound of the engine. I'll be recording startup, idle, loaded, and shutdown. Some of it can also be a rather high frequency, like the sound of the turbo spinning up and winding down at power off.

Any advice will be greatly appreciated!

-Farren

Do a google. There are companies in the trucking business, that have developed mic/sensors for engine parts. A computer samples the noises and then is able to determine if a part is functioning correctly. My friend developed a comparable system for tires. It alarms the driver when the tire will go, long before it happens. Pretty cool.

That said, it seems to me that you would need to buy a decent set of field recording mics, with a boom arm, wind sock, and field recorder (flash, HD, etc). This way you can maybe get some other local work with TV stations, advertising houses, etc developing a sound effects library or freelancing. I have another friend that made money recording NASCAR races like this.

Posted: Fri Nov 10, 2006 7:12 pm

As a point of reference ... I was once having trouble starting my car. A mechanic on an automotive email list suggested a diagnosis, but needed to hear the car to be sure. I put up a pair of Behringer ECM8000 mics ($40 each, omni - needs phantom) about 10 ft from my car off to the side. I wanted to capture all the sound. Mics were about 6ft from the ground and spaced at 27" (my default omni spacing distance). Mackie VLZ mixer for preamps.

This is the result.

As luck would have it, the car started while I was making the recording - no mechanic help needed.

Posted: Sun Dec 17, 2006 4:37 am

Many engineers spend too much time pointing the microphone directly at the source.
Do not forget what you are doing when capturing sound.
Microphone placement should be about capturing the sound that is in a particular space.
You are not shining a torch at an object!!
If you are trying to capture the essence of the whole engine stand back and capture the WHOLE sound of the engine walk around and listen for that sweet spot between exhaust and engine noise, because an engine produces a complicated mixture of sound, just pointing a microphone at one particular part of the engine will not capture the whole sound.

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