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SONY PD170 "hum" on audio recorded indoors

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jack Niedenthal
SONY PD170 "hum" on audio recorded indoors
on May 14, 2011 at 11:31:33 pm

I have a SONY PD 170 camera. When I record indoors, no matter where I am or whether I am using my Rode mic or my Seinheisser 416, I get this funny hum or buzz at the top end of the voice or in any music I try to record. It occurs whether on auto or manual modes. The weird thing is, it doesn't happen when I am outside, only when I am inside with little or no ambient sound (note: all electronics or off as are florescent lights, etc). Why would this be happening, is there anything I can do to fix it?


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Richard Crowley
Re: SONY PD170 "hum" on audio recorded indoors
on May 15, 2011 at 4:08:20 am

Suggested "differential diagnosis" tests:
Do you get the noise with the built-in microphone?
Do you get the noise when you plug the mic directly into the camera?
Do you get the noise when you use a different mic cable?
Do you get the noise when you use those mics with other equipment?


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jack Niedenthal
Re: SONY PD170 "hum" on audio recorded indoors
on May 15, 2011 at 8:55:38 am

Thanks Richard,
Your questions put me in the living room with 3 different mics and 2 cables, I don't have another camera to test the mics and cables on, so I used the PD170.

First I tried each mic with each of the 2 different cables. The hum was there each time. Then just for the heck, I plugged in 2 mics into the 2 xlr ports on the camera so I was getting sound from each mic, right and left. I flicked some of the switches on the camera, the Mic ATT switch, the cable 1 to cable 1 & 2 switch, etc. I also started switching between manual and auto sound controls. I then unplugged both mics, then just plugged in just one like I normally would when filming. Low and behold, no matter which mic I used, the hum/buzz was gone. I tried everything to get it back, but I couldn't so I am thinking the problem is solved, the scary thing is I don't know why. My fear is i go out to film and the hum/buzz returns because I couldn't really figure out what caused it... At any rate, thanks Richard, your questions prompted some experimentation that might have fixed the issue!


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Ty Ford
Re: SONY PD170 "hum" on audio recorded indoors
on May 15, 2011 at 12:12:57 pm

Hello Jack and welcome to the Cow Audio Forum.

In addition to Richard's check list, add this. Are you on AC inside and battery outside?

Hum is usually the result of an AC phenomenon. You only need one piece powered by AC to cause this. I was on a shoot last week in which the cameras were on battery. My mixer was on battery. The only AC-powered piece was the video monitor. We were using two cameras. The second input on the monitor was generating noise back through the ground of the coax. When we disconnected the coax to the #2 input, the hum vanished.

If you are on AC power. Try plugging camera and anything attached to it in any way into the same outlet to avoid ground loops.

Regards,

Ty Ford

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





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jack Niedenthal
Re: SONY PD170 "hum" on audio recorded indoors
on May 16, 2011 at 12:49:01 am

Thanks Ty, that is an interesting idea. I didn't use anything else plugged in when the humming/buzzing occurred, all equipment used was on battery power, but if the hum comes back what I might try is plugging in the camera for the recording session.


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Alan Lloyd
Re: SONY PD170 "hum" on audio recorded indoors
on May 21, 2011 at 4:15:56 am

Were there any incandescent lights on dimmers in use?


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