dvx100... recording gun fire... OK to use on board mic- Will loud sound cause damage?

justmarvin

justmarvin

Well-known member
I was wondering if loud sound can cause damage to the audio recording system inside the dvx100? I just recorded some real gun fire scenes, and I haven't yet had the chance to check it. But then I started to wonder if those loud sounds could pose harm to the audio recording system in the camera? Please let me know. Thanks.

JM
 
just stay away from digital zero and you should be OK. Personally I record live gunshots to analog tape. Tape compression is friendlier to fast transient sounds that may overload.
 
what's digital zero exactly? I tried to research it online but no luck finding any info. Thanks.

JM
 
The 0db mark on your DVX audio meter is digital Zero.

Just dont get anywhere close to being in the red and you will be fine.
 
I think I may have reached digital zero a few times then (I mean they were shooting rifles after all...). So I did hit the red mark, and I think it probably maxed out too?

How can I check to know for sure if the internal audio of the dvx100b was damaged in any way?

I turned on my camera and snapped my fingers and was talking in front of the mic and the meter is reading fine. Then, I put on a pair of professional headphones, and I listened to the audio I was getting from the internal mic... I noticed there was "noise" (i think that's the right word... as "grain/noise" would be the word for video image... i'm talking about the "noise" for sound). Is this normal for the on camera mic? I don't remember if that is or not. I was in a fairly quiet room when listening through the headphones. And I had the Automatic Level Control off. Anyway, I checked Rush Hamden's Digital Cinema Training tutorial dvd where they had audio samples for the hvx200's on camera mic and it seemed to have some noise there too but maybe mine is a little bit more pronounced. So is this normal for my dvx100b? Would having loud sound entering the mic, and hitting digital zero, make the mic "damaged" in such a way that it introduces "noise" into the mic in future use? How do I know if anything happened that I should be concerned about?

I plugged in my AKG cardioid and shotgun and then the noise was drastically reduced. Does that mean everything is fine and that's just the way the dvx100b on camera mic is supposed to sound like?

Please let me know.

Thanks,

JM
 
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depending on the impedance of the headphones you used, the little amplifier in the camera may make more or less idle noise. The same goes for the onboard Mic vs. External Mic. it's difficult to say if you have done any damage, but my guess would be no.

does the audio sound fuzzy outside of the camera, in the captured audio files?
 
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General Audio Info.

General Audio Info.

The reason it is important to stay away from the red is because you will get distorted recordings. There are two different kinds of DB (decibels): dB-SPL & dB-FS. 0 dB-FS is what is used on your camera to monitor audio levels.

dB-FS..... This is what is measured on your camera's viewfinder. The term stands for decibel full scale. dB-FS, is used to measure the increments of decibels below the distortion leve (that is why 0 dB is at the top). Your measurement should always be a negative number. It cannot be positive without there being some kind of distortion. It is always a good idea to try and average you audio at a -10 and try to leep your peaks around -5 so that just in case something were to happen you have headroom. (Although if you are doing a gun shot you would need to lower the volume. ***0 dB-FS is the point at which any audio signal is distorted. ***

When audio is concerned, here is a great quote to live by..................GARBAGE IN, GARBAGE OUT. Once the audio is recorded, it's hard to fix problems. And in the case of "clipping" (distorted) levels, it is physically impossible to fix. Make sure to record right the first time.
 
Right, but this thread is talking about a DVX, and it's important to point out that the DVX's "red" scale begins at -12dB! So on the one hand you're saying "stay away from the red", but on the other you're saying "average at -10l, peaks around -5" -- and on a DVX, both of those would be in the red.

On the HVX they did it much less frighteningly; it's white everywhere except at clipping. But on the DVX the whole top of the scale shows up as red. So when working with a DVX, don't be scared of the red color; you can go a little red with no problem. There are six dots of red, you can set your peaks at two or three red dots and you'll be getting your peaks around -6.
 
thanks barry and mb for the tips :)

badjuju: I haven't heard it on the computer yet, but the footage playing on the tv seems normal I guess.. obviously it was clipping on the gunshots though, but nothing wrong really stands out. What do you mean by "fuzzy" though? I was watching the footage on the TV and also on the LCD screen, and I see the meter maxing out to the end which is "0" it's done that several times. But again when watching the footage on TV nothing really out of the ordinary stands out.

So when I upload the files on my computer, what should I be checking for? If the audio sounds normal then that means everything is A-Ok? The "noise" isn't really an issue right, that should be normal for on-cam mics? Also, if the loud sound did do some damage, would that only affect the on-camera mic? Or would that also be a problem for being able to receive good sound from external mics connected to the cam?

JM
 
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To answer what I think is your real question. Your camera is fine. Stop worrying about it.

People shoot with the DVX in concert situations all the time. I myself have been in several of these situations where I was placed right beside or in front of the FOH main speakers. The amount of sound pressure there is greater than a gun shot depending on how far away you where from the gun and it is for 3-4 minutes at a time constant.

My camera is fine...your camera is fine.

Your audio on this particular tape will be distorted when the gun shot is fired. Other than that no harm is done.

Isn't this what you where worried about in the first place?
 
If all of the remaining audio sounded fuzzy then you trashed the mic elements. If the gunshots clipped, and the rest of the audio is clear, not distorted, the keep on shooting. (with the DVX not the guns :D)
 
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