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Levels okay, but microphone overwhelmed?

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Sandy Chase
Levels okay, but microphone overwhelmed?
on Jan 30, 2011 at 5:30:50 pm

I'm no audio pro, so I'm trying to figure out what's going on here. I've recently used two different professional production-audio people on two different live events, and I've seen the same issue.

Basically, the peak levels seem okay, but all the waveforms are chopped at the top. It's like the overall inputs were set to a safe level, but the microphone diaphragm or whatever is getting overwhelmed. Can anyone sort this out? I want to prevent this from happening AGAIN in the future. Thanks!! I'll try to post an image. (There was no post-processing on this. It's straight from the field recorder.)


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Steven Talley
Re: Levels okay, but microphone overwhelmed?
on Jan 30, 2011 at 8:26:32 pm

Levels for mics are too high. Were the recordings in a overly loud situation like a concert? Were these built in mics or handheld.
Condenser or dynamic?

I've used the Tascam dr-2d recorder which has dual recording to insure you get a usable recording in most situations. It records a main stereo track and a second stereo recording at -6db from the main setting.

I'd try setting the level on the low side using 24 bit recording for more headroom.


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Sandy Chase
Re: Levels okay, but microphone overwhelmed?
on Jan 30, 2011 at 8:36:05 pm

I think one was a Sennheiser ME-66, two were wireless mics, like lavs, and I don't know what the fourth one was. The music was super loud percussion in parts. Audio guy used some type of field recorder.

The rec levels were okay, but obviously something is getting slammed in the system here. I can't imagine this is the most accurate recording I can get from these mics. I need like an "ND filter" for audio. Or else just put them further away if possible??


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Nick Griffin
Re: Levels okay, but microphone overwhelmed?
on Jan 30, 2011 at 10:46:55 pm

[Sandy Chase] " I need like an "ND filter" for audio"

Sandy it's called a "pad" and some mics, especially higher end condenser mics, have it built-in so you are actually attenuating the signal before it reaches any electronics in the mic. For dynamic mics, which should be able to handle higher levels without going into distortion because they are somewhat less sensitive, pads can be added in line prior to reaching the mixer or pre-amp. Most mixers also have "trims" built-in to dial-down the input prior to reaching the rest of the electronics.

Oh... and thank you for visiting Ty Ford's Audio Professional's COW forum.


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Jordan Wolf
Re: Levels okay, but microphone overwhelmed?
on Jan 31, 2011 at 7:03:39 am

Sandy,

Are all of the audio files that way (shotgun AND wireless mics) or only the shotgun or wireless mics' files?


Wireless mics have several extra stages that their wired counterparts do not, and there can be distortion/overload in any one (or more) of them.

If that is not the case, then an overloaded diaphragm could be one culprit, as could improperly calibrated levels between devices (Line Input vs. Mic Input, gain settings, etc.).

Wolf
<><


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Frank Nolan
Re: Levels okay, but microphone overwhelmed?
on Jan 31, 2011 at 10:14:24 am

Without knowing the EXACT audio chain it is hard to say with any certainty where the problem was, but the fault certainly lies with the "audio professionals" you hired.
In the case of the Me66, It could have been at the mic input to the mixer or from the mixer to the recording device. As for the lavs there is another 2 places it could have been. On the transmitter or the receiver.
Also depending on the mixer being used, it may be that it had a hard limiter on that was being slammed.
Unfortunately dealing with what you have is a bit like dealing with an overexposed shot. You can try and make it less bad but it will never be good.
The team at izotope have one of the better products on the market for helping with this kind of stuff.



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Rob Neidig
Re: Levels okay, but microphone overwhelmed?
on Jan 31, 2011 at 3:54:18 pm

It seems to me that with the straight-line tops that this waveform displays, that it is not an overload of the mic element. It almost certainly is the input recording level to the audio device. If the recording levels were properly set, and the mic element was overloaded, you would not get the chopped off tops on the waveform, even though you would be getting a distorted sound. So I would look at his audio input levels to the recorder, or at your input levels to your editing software.

Have fun!

Rob

Rob Neidig
R&R Media Productions
Eugene, Oregon


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Sandy Chase
Re: Levels okay, but microphone overwhelmed?
on Jan 31, 2011 at 4:45:49 pm

But if the input levels were too high, why are the recorded levels only at about -6dB? In Final Cut Pro, if the audio is peaking, those waveforms would stretch all the way to the top and bottom of the window. They would be slamming 0 and giving me distortion. I think there's something earlier in the chain that's maxed out, then the final stage (the recording device) is set to a safe level.


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Bob Kessler
Re: Levels okay, but microphone overwhelmed?
on Jan 31, 2011 at 5:24:00 pm

I'm just curious...

The waveforms are flattened top and bottom, but is the actual audio itself distorted when you listen to it?

I don't know anything about NLEs, but in DAW programs you can adjust the size of the waveforms. I sometimes have to increase the size of the waveforms to find artifacts and/or edit points, and the rest of the audio looks like your screen shot.

I've also seen waveforms that look like that when a brick wall limiter is used on the mixer; the audio pumps and breathes but is not (terribly) distorted.

Peace,

Bob
____________________________________________________________________
Filmmaking is the art of the invisible;
If anyone notices your work you haven't done your job right.


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Ty Ford
Re: Levels okay, but microphone overwhelmed?
on Feb 1, 2011 at 4:58:49 am

Hello Sandy and welcome to the Cow Audio Forum.

This looks like line level feeding mic level input. What was between the mics and the recorder?

What was the source of the sound?

BTW, to keep this from happening in the future, all you have to do is have a good pair of headphones plugged into the recorder. My choice is Sony MDR7506 or Audio Technica ATH M50.

Regards,

Ty Ford

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide





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