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Hum/Buzz from Mic

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Jack Sammanson
Hum/Buzz from Mic
on May 30, 2009 at 9:10:40 pm

I went out and bought a cheap dynamic microphone the other day from the local music store. I'm not looking for anything big right now, just a step up from my camera's on-board microphone.

I've shot a few test films, and noticed that there is a hum/buzz from the mic when recording. Whether I hear it in the headphones or not, it will always show up in the footage. I have it hooked into my camera so that it starts with the mic, then through an XLR-to-3.5 mm cable, into a 1/8" adapter, and finally into the camera's external mic jack.

When I use this mic to speak through a normal amplifier, it works just fine - no buzz/hum.

How can I solve this problem?


Thanks!
Jack


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Ty Ford
Re: Hum/Buzz from Mic
on May 30, 2009 at 9:43:51 pm

Hello Jack and welcome to the Cow Audio Forum.

First, if you can't hear it in the headphones when they are plugged into the camera, you need better headphones. Buy Sony MDR7506 headphones at your earliest convenience.

Second, you don't provide any information as to the wiring of the 1'8" TRS plug or the input of your camera. Most cameras have stereo input jacks. Unless your XLR to 1/8" cable is wired properly, it will cause a buzz.

Third, dynamic mics are of low sensitivity. The require more gain than most condenser mics. That gain also brings up noise. That could also be the source of your buzz.

As you continue on your path and start doing projects professionally, you will learn that you can't afford to buy cheap.

Regards,

Ty Ford

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






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Jack Sammanson
Re: Hum/Buzz from Mic
on May 30, 2009 at 10:03:09 pm

I'm not quite sure what information you are looking for, but yes, the camera's input is stereo.

And thank you for the headphone suggestion. I've been looking for a good pair for a while now. I'll definitely look into those.


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Ty Ford
Re: Hum/Buzz from Mic
on May 30, 2009 at 10:26:40 pm

Jack,

They are $99 USD. Don't look, just buy. These are industry standard. They are because they are sturdy and tell you what you need to know about the audio coming in to your camera.

The XLR to 1/8" cable you have is probably not wired for stereo. You need one in which the #2 pin from the XLR connects to both the tip and ring of the 1/8" plug. Some cameras put a low voltage on the jack to power certain mics. This voltage may be useful, or may cause noise or distortion.

There are cables built with a blocking capacitor that keep the voltage from causing problems. here's one.
http://www.trewaudio.com/store/product.php?productid=146&cat=21&page=1

Yes, it costs $50. You can try adapters but they are usually too funky mechanically to be reliable.

Regards,

Ty Ford

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






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Jack Sammanson
Re: Hum/Buzz from Mic
on May 31, 2009 at 4:06:23 am

Alright, I will get those.


And also, could it be that I'm using an XLR to 3.5, then 3.5 to 1/8"?


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Ty Ford
Re: Hum/Buzz from Mic
on May 31, 2009 at 11:16:37 am

Hi Jack,

The issue is getting the 2-pin to both the tip and ring of the 1/8" trs plug. Adapters can be wevy twicky.
::Elmer Fudd reference::

Regards,

Ty Ford

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






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Jack Sammanson
Re: Hum/Buzz from Mic
on May 31, 2009 at 5:21:59 pm

So how would you suggest I do that? Maybe getting a cable that goes straight from XLR to 1/8"?


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Ty Ford
Re: Hum/Buzz from Mic
on May 31, 2009 at 7:41:38 pm

I would suggest you get the cable I told you about three posts ago on this string.

Ty Ford

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






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