Mics and Gunfire

gco

gco

Veteran
I recently shot a reenactment run & gun style with an on-cam 4073. I was on the ground to the side of and slightly ahead of about 30 guys firing simultaneously. I turned the preamps down to about 1/4 and still got clipping. Shooting from behind the group, the sound was better with minimal clipping. I also noticed that gunfire from other groups on the field was not as present nor was the canon fire echoeing off the treeline as present on the tape as I had hoped. (I did turn the preamps up a bit after being out front.). So I'm wondering if this might not be a situation for using a hyper outside instead of a shotgun??? I searched the threads and found only one reference -----

From AdamL quoting a Ramps thread:
"I have only had a few precious moments to listen to the new Schoeps shotgun
microphone (actually, it seems strange to even say "Schoeps" and "shotgun"
together), MI 3 as most of you know, has few scenes that benefit from this
sort of microphone. One of our favorite mics on this movie is the Octava
because it holds up to the assault of noise, gunfire, explosions and so
forth, that we are doing. "

Assuming his Octava is a hyper, it seems like it might be a better way to go for gunfire. Not only for holding up to the shockwaves but possibly fuller sound/greater ambiance with less tendency to clip???. Anyone have any experience/suggestions concerning shotguns, hypers and gunfire?
Gary
 
If your not using a mixer for its limiters to protect your levels, then I read 30db of pads for the oktava is needed! I'm curious cause I need to do something similar next year, myself, and have been reading up on high SPL recordings! I would like to get a recommendation on a ''make and model Dynamic mic'' [Cheap] that would work in this situation? Cheap= < $300.00

here another post for gunshots

http://www.dvxuser.com/V6/showthread.php?t=63160&highlight=gunshots
 
I don't use condensors for guns if the mic is going to be anywhere near close. They can puke out easily. Something like a Sennheiser MD421 is a better choice for closer stuff. You have to check the Max SPL specs of mics that you want to use for guns to make sure they won't get crunched.

-Dave
 
bwest said:
If your not using a mixer for its limiters to protect your levels, then I read 30db of pads for the oktava is needed! I'm curious cause I need to do something similar next year, myself, and have been reading up on high SPL recordings! I would like to get a recommendation on a ''make and model Dynamic mic'' [Cheap] that would work in this situation? Cheap= < $300.00

here another post for gunshots

http://www.dvxuser.com/V6/showthread.php?t=63160&highlight=gunshots
Click to expand...
Ok, so based on what was stated in that thread and what Dave said, it looks like a dynamic is a better way to go. Makes sense I suppose; a dynamic having more surface area and not being polarized like a condenser and thus less sensitive to sharp transients?......I thnk.
On the other hand, its tempting to use the Octava since I already have it and a couple of inline 10dB pads should be cheaper than buying a dynamic. However, I'm not real clear on how the 10 dB pad works. Is it for shifting the entire frequency response down in volume? OR does it compress the frequency range, low to high?. If using a mixer, does a pad create more headroom before the mixers limiter kicks in?

Gary
 
The reason a dynamic mic is better at handling high SPL environments with sharp transients has to do with the electronics, not the capsule. A condensor is sensitive because it uses transistors: very quick devices that only require a few electrons to register a sound wave (which is why they always require additional power to amplify their signal.) Dynamics use transformers instead of transistors, which require sound pressure so physically move a magnet. Even in the tiniest dynamics, Newton's laws apply: the energy required to move the magnet (and then to stop it and move it back in the other direction at the top and the bottom of each wave) is vastly larger than the energy required to change electron flow in a transistor. Okay, I know that's technical; let me know if it doesn't make sense.

Think of starting a car: a condenser mic is like turning a key, while a dynamic mic is like the old cars with the crank on the front. The key is obviously quicker and takes less effort than the crank, but requires a battery. If you think of this happening several thousand times every second, there are going to be times where the crank isn't going to get the car started by the time the next sound wave gets going again in the other direction. (Analogies at 3am leave something to be desired.)

A pad completely depends on where it is applied. If it's applied in the mic itself, it gives you an extra 10dB before the mics electronics distort: nothing will change the level that the capsule distorts at, but that is usually so high that you will have everything else peaking first. If you apply a pad in your mixer, it will lower the level of the signal coming from the built-in preamp, but if the mic itself is still to hot, you're still going to get the distortion. In your words, they would both shift the entire frequency response down in volume... technically it's effecting voltage, not volume. Ultimately, you only want to pad the electronics that are distorting; practically, that means adding the pad as early as possible in the signal chain. Hope this helps.
 
shawnmaddock said:
The reason a dynamic mic is better at handling high SPL environments with sharp transients has to do with the electronics, not the capsule. A condensor is sensitive because it uses transistors: very quick devices that only require a few electrons to register a sound wave (which is why they always require additional power to amplify their signal.) Dynamics use transformers instead of transistors, which require sound pressure so physically move a magnet. Even in the tiniest dynamics, Newton's laws apply: the energy required to move the magnet (and then to stop it and move it back in the other direction at the top and the bottom of each wave) is vastly larger than the energy required to change electron flow in a transistor. Okay, I know that's technical; let me know if it doesn't make sense.
.................
Click to expand...
Ok, so your point is that the signal in a dynamic is directly related to the physical energy (sound pressure) creating movement as opposed to minute changes in transistor electron flow. That would make perfect sense to me as to why a dynamic is better for high SPLs. Now I get it. I suppose that would also explain why a condenser might get damaged in high SPLs. The transistors could be overdriven by sharp transients.
 
shawnmaddock said:
.........................
A pad completely depends on where it is applied. If it's applied in the mic itself, it gives you an extra 10dB before the mics electronics distort: nothing will change the level that the capsule distorts at, but that is usually so high that you will have everything else peaking first. If you apply a pad in your mixer, it will lower the level of the signal coming from the built-in preamp, but if the mic itself is still to hot, you're still going to get the distortion. In your words, they would both shift the entire frequency response down in volume... technically it's effecting voltage, not volume. Ultimately, you only want to pad the electronics that are distorting; practically, that means adding the pad as early as possible in the signal chain. Hope this helps.
Click to expand...
So the pad is more relevant to signal voltage as opposed to volume and it goes in line as early as possible to prevent anything downsteam from distorting. Shawn you just turned the lights on. Pretty damn good answers for 3am btw. Thanks so much!!!
Gary
 
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