How to record big rockets in a rocket test facilty

[Ale]

Hello

I have to record sounds of some heavy big rocketmotors in a test bench.
I wonder, what microphones would handle that very high sound pressure?

Any experience with this?


Thanks
Ale

[Darryl Ramm]

Out of curiosity is this a full size rocket or model? Depending on what you are trying to do I could imagine a crossed stereo pair used to pick up the environment, echoes off the ground etc. quite interesting.

My starting point would be an SM 58 or similar dynamic mic, a choice of several big attenuator pads and suitable distance. Close mic'ing not recommended. Also check now close you can get for safety and wether you are going to leave the mic and recorder close with no operator etc. and how all that is going to work.

[Ale]

Real big rockets with a soundpressure far over 150dB

[reichman]

I've seen brochures and info about B & K's industrial department where they measure and record extraordinary things. I think they spun off their pro-audio division, but they would definitely be worth calling. I've never recorded anything with 150db.

http://en.wikipedia.org/wiki/Br%C3%BCel_%26_Kj%C3%A6r

[Darryl Ramm]

Surely there is a distance you can be at where the SPL is below 150. Which is around the sometimes quoted nominal max SPL of dynamic mics... but which is very frequency dependent and I am guessing loud rockets have significant energy down around the typical dynamic mic primary resonance frequency (~100Hz or so).

Again it's not clear exactly what you are trying to do. There are very high SPL exotic microphones, often piezo mics, that the test stand or parts of the rockets may be instrumented with. Which may or may not be totally useless/unavailable to you or maybe you can borrow what they are already recording. Even if quite unusual frequency response there might be interesting things there to play with. You will need to talk to the test facility/rocket engineers.

Not sure what you are doing exactly but there was something on TV I saw recently where a rocket engine was test fired and the camera zoomed in and out to let you know you were really watching from a distance and then there was a noticeable delay between seeing the rocket being seen to fire up and the sound reaching the camera location and a nice stereo sound field and still loud noise. That delay just really said "yep you are far away and this is still really loud".

[Kasper]

Gefelll has some condensers that'll take @ 170 - - look at their measurement/environment mics, not their music mics.
(alot of it only in German, unfortunately for me, maybe not for you ;-)

Also, I've done really loud stuff with PZM mics, cheap Crown PZMs.
I have no idea the actual SPL, but loud explosions, guns, etc.


kasper

[Ale]

I am in contact with B & K and thanks for those other good ideas Kasper

BK dont rent those mics. Its about 5-6K Dollar including the special power supply since this mic has a "Phantom" power of 200 Volt.

Their techncan told me that a rocket has a SPL somehow between 180-190 dB

I have to record this rocket far and as near as possible. I think recording only from distance would be also very loud.
You are right Darryl: I think I have to talk to the engineers to get an idea what spl to expect in what distance

http://www.dlr.de/next/desktopdefaul...33_read-24886/

Ale

[Bob Olhsson]

An omni dynamic mike. You may need to use a line input rather than a mike pre.

[albee1952]

Curious as to how a cone would work here(like the Yamaha Sub-kick, NS-10 woofer setup, or maybe all the way up to a 15" or 18" speaker)?? Certainly, distance can be used to attenuate the sound pressure(I wouldn't want to be too close either)

[Brandonx1]

Originally Posted by albee1952

Curious as to how a cone would work here(like the Yamaha Sub-kick, NS-10 woofer setup, or maybe all the way up to a 15" or 18" speaker)?? Certainly, distance can be used to attenuate the sound pressure(I wouldn't want to be too close either)

I think that is a genius idea! I'd tray that along with a good mic.