Name that Noise?!
 

About 14 minutes into a 17 minute clip, I started getting noise that sounds like the pops and crackles of an old, scratched LP record. I had a shotgun mike on a boom, so nothing was rubbing against the mike.

This is the noise:

http://users.gmavt.net/powerdog/grap...oiseSample.mov

Other equipment used:

Canon XL-H1
Macbook Pro w/ Bootcamp & Win XP
DV Rack HD

For most of the clip, the sound was fine. Any thoughts? Thanks.

Someone in the room have a cell phone or Blackberry turnend on?

Were you using any wireless?

Was the microphone working on phantom power or a battery inside?

It could also be a loose or damaged wire.

No cellphone or wireless mic. The wired mic was on phantom.

Maybe the XLR cable is the prime suspect?

Were you recording to the laptop or just monitoring with it?

To me it sounds like the mic is losing phantom power, or, if an internal battery, losing contact with the battery. Maybe. Such a problem could be at the source of phantom (camera?), in the cable, oxidized/corroded connectors, or in the mic itself.

Nothing in my experience with DVRack, and I've used it a lot, suggests that this could be laptop or DVRack related. Were you backing up to tape, does the tape show the same issue?

The real test is if you're able to reproduce the problem - then you can start narrowing down by using a different mic, a different cable, a different source of phantom.

Yes, it could be the XLR cable or a bad connection. Best thing to do it take the XLR cable that was used and see if you can recreate the sound. Then try it with a different XLR. Pretty much have to narrow it down one piece of equipment at a time.

Once it started happening, did it keep going in and out or did it stop?

Best,
Andy

Andy, the amount of noise gradually went down to none, over a period of a couple of minutes. I'd be less confused if the noise were consistent, but I can't correlate amount of noise with anything I remember.

I was shooting an awards event once and had to switch back and forth between two cameras so I didn't get to monitor the audio at all times. When capturing I noticed pops, cracks, and sometimes even audio dropouts at certain points. With my clever investigating skills I realized the wait staff would step on my XLR cables that ran from the banquet hall sound system under a rug to my camera. So as dinner was served (and more detrimental as coffee and dessert were served as a key speaker was on stage) I got the pops and cracks.

Did you have any foot traffic near cables as well?

Nope. Just the 2 people I was interviewing on one side of the camera, and me on the other.

BTW, what do you think was happening when your cable was stepped on. Was it somehow making the various wires inside touch?

Can you give us a longer section of the clip? Perhaps the transition where the sound begins and ends?

To me it sounds like a dirty connection at an XLR end.

what mic where you using ?

maybe humidity problem ( too much ) as in cold mic into warm room. as the mic dried out, it went away.

if it was a lav, lav wires go bad. I've had them break, or get intermittent and have to make a splice in the field to fix it. not easy when its right below the capsule.

I also just tracked down an intermittent problem with my boompole. one of the solder joints on the XLR mic end was bad. the wire was in the solder, but it was loose because it wasn't quite hot enough when soldered to make a solid connection. re did the connection and so far, so good. had noise similar to this as mic lost / gained phantom power. I'd open all the XLR ends and check for a bad connection, maybe even just resolder ( heat ) them just to be sure since these things can be sneaky.

also, what mixer ? maybe batteries going dead ?

or too many phantom powered mics running at once for mixer to power.

its not a cell phone hit, you would know that as digital noise.