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Gunshots bad for mics?


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#1 Lance Boyle

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Posted 02 May 2006 - 04:32 PM

I have an Azden SGM-2X shotgun mic that I will be using to shoot a WWII battle scene, and later, an indoor scene in which the lead character fires a .45 in relatively close proximity to the mic.

Are gunshots bad for these mics, or are they built to handle the sound?
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#2 Lance Boyle

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Posted 08 May 2006 - 08:52 PM

I have an Azden SGM-2X shotgun mic that I will be using to shoot a WWII battle scene, and later, an indoor scene in which the lead character fires a .45 in relatively close proximity to the mic.

Are gunshots bad for these mics, or are they built to handle the sound?



NOBODY knows? In the sound forum?


Hmmm...
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#3 Matt Pacini

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Posted 16 May 2006 - 02:35 PM

All mics are rated at certain db levels, and it is a mechanical instrument, so yeah, it can be damaged.
Enough SPL can have the same effect as dropping it.
Look at the specs for your mic, & find out what the level of a gunshot is (sorry, I don't know).
My gut reaction is, why do you have to have the mic close to the gun?
My second gut reaction is, there are going to be so many reflections off the walls, etc., that I'd think you are almost certain to need to dub a clean gunshot in later anyway, so just don't record it, (or record it at a safe distance), and do this one in post.
Even if it were possible to get a good clean recording of a gunshot indoors, you're only going to get that one take, so it's unlikely you're going to get a decent one anyway.
Dub it in post.
Save your mic.

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#4 Robert Hughes

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Posted 16 May 2006 - 03:11 PM

Gunshots emit damaging amounts of gas near the barrel. Heck, that's the point of firearms, to inflict damage. Remember that TV star who accidently killed himself by shooting a blank into his head?

Yes, a microphone placed too close to a gun barrel muzzle can be damaged. How close is "too close"? Depends on the microphone - a studio condensor microphone can overload at about 120 dB, an SM58 around 135 dB. I think a gunshot gas pulse near the muzzle is up around 170 or 180 dB. Use a mic you can afford to toss if you damage it.

Edited by Robert Hughes, 16 May 2006 - 03:13 PM.

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#5 Matt Pacini

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Posted 19 May 2006 - 03:50 PM

Yep, I remember.
Jon-Ercic Hexum.
http://imdb.com/name/nm0382149/

Actually, it was the wadding they use for blanks that killed him.

You're right, a Sure SM58 (or SM57) would probably be the best mics for this, as far as being robust, but unfortunately, they aren't the greatest sounding mics - kinda mid-rangey.

I'd just dub it in later in post. There are much better gunshot recordings than you're ever going to get.

MP
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#6 Peter Duggan

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Posted 30 May 2006 - 04:14 PM

It can be bad for the mic. When you're firing a gun, it is sending out a very loud noise. This vibrates the capsule in your mic, and if it goes over a certain level (I'm not sure what it is on the Azden mics), it can blow the capsule even if the mic isn't plugged in. Luckily though, the Azden mics are crap and it would probably be for the best if you blow the capsule on it. Pick up a Sennheiser next time.
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#7 Alan Duckworth

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Posted 31 May 2006 - 06:31 PM

If you really want to record a live gunshot, I would suggest using an AKG D112 mic. These are designed for high SPL's (the instruction manual states that the "Maximum Sound Pressure Level is unmeasurable"). Music studios use them for recording kick drums, and they can even be placed inside the drum! The sound quality is very decent though, because it is a 1" capsule (like studio condenser mics). They are available for about 200 dollars or less, but a local music studio might loan you one - they are quite popular in studios that record a lot of rock music.

Your biggest problem will be setting your levels - the output from this mic at high SPL's is very high indeed, and it will probably need to be padded down, especially if you are going into a digital recording device of any kind. It will overload most inputs that are made of integrated circuits ("chips") - this is one of the reasons professional music studios still use pre-amps made of discrete components, and even tubes.

Having said that, I agree with others here that you are probably better doing this in post with pre-recorded gunshot SFX, or make your own. Try slapping two pieces of wood together close to the mic. Do this a number of times then run the raw recordings back through an effects processor and re-pitch to find the sound you like (I use a Lexicon MPX100 [less than 300 dollars] for this stuff; the reverbs in it are a bit "digital" sounding, but the FX algorhythms are cool, and the delays and pitch controls are very good).
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#8 Alessandro Machi

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Posted 04 June 2006 - 05:39 AM

Besides the issue you raised, the issue of padding the audio is of equal importance. Your likely to get a distorted sound even if the mike is not damaged. I'm just guessing but Probably a -20 to -25 PAD is what you will need, although a large part will depend on how close to the sound your microphone is.

And, when using a pad, make sure auto gain audio is disabled or all you will do raise the floor bed of the ambience in the room and end up with ultra compressed audio as well.
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