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Old July 30th, 2009, 06:26 PM   #1
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Can anyone identify this noise?

I am using a Panasonic AG-HMC70 AVCHD camera. It's worked fine up until the past few weeks, where it has developed a strange rhythmic buzz/noise during recording.

The sound is only present during recording, and is there if I use the onboard mic, or use an external mic that's connected via XLR. The noise can be heard also if I put my ear to the on-board speaker, even if the monitor volume is turned right down. It's present regardless of if the camera is on battery or wired power. Basically, it's always there!

The most annoying thing is that the sound is also present on the video. I've put a very small clip on YouTube so that you can hear it (you'll hear it best when the guy stops talking at the end).

YouTube - Sequence 1 Untitled Project 1 H 264 for Apple TV

It seems to be something onboard. Can anyone identify it? Also, could I get rid of this during post production? I completed 6 videos for clients today, all need to be completed for Monday and the sound is present on each and every one of them :)
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Old July 30th, 2009, 06:32 PM   #2
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If you're talking about the constant noise throughout, it sounds like noise floor to me. As if you've had to raise the volume in post to make up for insufficient signal and/or recording levels (possibly due to lack of proximity of the mic to the sound source).

As well, I've found that when using condensor mics hooked up to use phantom power on a camera, sometimes it takes a couple of minutes for the voltage to become "stable". I don't know how else to explain this other than to state that noise leaks into recordings until the camera (and mic) have had a chance to "warm up".

Also, if you're using a wireless mic, it may be noise from a "noisy" channel or perhaps the receiver isn't accurately "locking on" to the transmitter's channel.

If you share a bit more about how the speaker's voice is being recorded, perhaps we could help more.
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Old July 30th, 2009, 07:59 PM   #3
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Definitely sounds like something onboard. Have you tried different cards to record to? Perhaps reformatting the cards again?

Not sure if you can get it out easily, you might have to do some spectral repair.
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Old July 31st, 2009, 04:56 AM   #4
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Noise

I am hearing 3 noises:
The First is the "hiss". That seems to be is the noise floor. Not much you can do about that(Filter, Noise Reduction algorithm?)
The Second is a "galloping" sound. I usually hear this when my cell phone is too close to my radio in the van, However, I don't hear it as regulrly as it seems to be on your recording. Got a cell phone in your pocket?
The Third is a low frequency "fluttering". I have picked up something like this when I have used an AC adapter on the camera(as opposed to battery) AND taken a an audio line feed from a mixer through the XLR inputs. Go Battery or try to find a way to lift the ground on pin "1" of the XLR, use a line transformer between the camera and the mics.
Sorry I could not be more helpful Good luck with your deadline.
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Old July 31st, 2009, 01:40 PM   #5
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Tracy's right about the "galloping" sound, I think, somehow cellphones - particularly Blackberries --- have a way of inducing that sound into audio. I get that when using wireless mics, but this week had one in a hardwired system, taking a feed from house audio. Pervasive problem. The big rumble at the end sounds like somebody bumping the on-camera mike while handling the camera...I say that's what it sounds like, don't know if you had an on-camera mic but the audio has that distant-from-the-subject sound to it. A lav on the subject would probably let you get a better voice amplitude and thus you would not raise your noise floor so much, nor pick up room ambience so much....hth / Battle Vaughan/miamiaherald.com video team
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Old July 31st, 2009, 01:59 PM   #6
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I have some new information:

This is an AVCHD camera, and uses SD cards. I swapped the current SD card in the camera for a different one (this time a Pansonic branded card) and the noise (the one that sounds like it may be from a cellphone) dissappeared. However, about ten minutes into using this card it came back again.

It's very strange as I have no phones etc inside the studio. I've narrowed it down to having something to do with the SD card reader inside the camera perhaps?

The fluttering - yes this seems to happen when running off AC power. It's correctable by switching to battery.

Any suggestions on the SD issue?
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Old July 31st, 2009, 03:29 PM   #7
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Quote:
Originally Posted by James Collins View Post
I have some new information:

This is an AVCHD camera, and uses SD cards. I swapped the current SD card in the camera for a different one (this time a Pansonic branded card) and the noise (the one that sounds like it may be from a cellphone) dissappeared. However, about ten minutes into using this card it came back again.

It's very strange as I have no phones etc inside the studio. I've narrowed it down to having something to do with the SD card reader inside the camera perhaps?

The fluttering - yes this seems to happen when running off AC power. It's correctable by switching to battery.

Any suggestions on the SD issue?
Is the camera upgraded to the latest firmware? Do that, if no dice... send it in for servicing.

This really reminds me of the hvx-200 beeping problem that appeared on earlier firmware versions of that camera. It was remedied by formating the cards again or upgrading the firmware.
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Old July 31st, 2009, 03:46 PM   #8
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How do I upgrade the firmware?

Also, is it worth me formatting the SD cards? Both are having the same problem, so it makes me think it is an on-board issue instead.
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Old July 31st, 2009, 06:35 PM   #9
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Quote:
Originally Posted by James Collins View Post
How do I upgrade the firmware?

Also, is it worth me formatting the SD cards? Both are having the same problem, so it makes me think it is an on-board issue instead.
You should probably ask one of the camera forums on this site. I'm just a sound guy, so I can't really get into technical and firmware aspects of the camera.

Considering you have used two different cards.. the problem is likely on camera.
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