getting a annoying hum

T

tony404

Well-known member
Wanted to use my shotgun on the camera(dvx100a) I have a Audio Technica AT815b.
I know its very long, I bought before I had the camera a while ago. I love the sound I get from the mic. I put it on the camera on the hot shoe with a L shaped bracket ( I forget the tech name for it ) it has three places you can connect the mic holder to. I use the high one so the mic isnt in the shot. The mic holder Im using is the one that came with it ,its hard plastic. I keep getting a hum that comes and goes. When I take the mic off the camera I dont have it only on the camera. Any suggestions for a fix that doesnt cost a ton of money.
 
Does the "hum" only occur when the mic is in mechanical contact with the camera, or does it occur when it is in close proximity?

If it is the former, then it is likely caused by a leakage path to the mic's body.

If it is the later, then it is induced and could be helped by adding a magnetic shield.
 
did you try putting the mic into the other xlr input? it could be a connection issue. try the other input, and then try another xlr cable. This has happened to me before and most of the times it was broken hardware. ie, the cable being internally rusted. try changing the battery in the mic as well (if it has one...)
 
khmuse said:
Does the "hum" only occur when the mic is in mechanical contact with the camera, or does it occur when it is in close proximity?

If it is the former, then it is likely caused by a leakage path to the mic's body.

If it is the later, then it is induced and could be helped by adding a magnetic shield.
Click to expand...
only when it makes mechanical contact to the body its attached to the hotshoe on a metal bracket in a hard plastic mic holder . if i take the mic off the holder and hold it in my hand there is no noise
 
tony404 said:
only when it makes mechanical contact to the body its attached to the hotshoe on a metal bracket in a hard plastic mic holder . if i take the mic off the holder and hold it in my hand there is no noise
Click to expand...

Simple. The microphone or the cable has a fault (shorted connection) between ground (pin 1) or the body connection and either of the signal pins (pins 2 or 3).
 
khmuse said:
Simple. The microphone or the cable has a fault (shorted connection) between ground (pin 1) or the body connection and either of the signal pins (pins 2 or 3).
Click to expand...
That wasn't it bought a new one does the same thing it sounds like a motor noise but only when it is sitting in the mount attached to the camera if I got a shotgun mount instead of the hard plastic think that would make a difference?
 
Just to clarify, you replaced both the cable and the mic? Do you have access to a multimeter?
 
khmuse said:
Just to clarify, you replaced both the cable and the mic? Do you have access to a multimeter?
Click to expand...
I replaced the cable only , I dont think I'm making myself clear.
I have shotgun attached to the camera with a hard plastic mic holder and the xlr cable. Im recording Im getting the sound of the tape motors included in my sound. Now if I take that mic out of the holder but still attached to the same cable there is no motor noise.
 
I guess I am confused. Are you saying you are not using a proper shockmount but a hard plastic mic holder (ie: like the kind you use on a mic stand)? Is it a hum, a motor noise, or both you are concerned about?

If you are not using a shockmount (a mic holder that has some sort of vibration dampening function, like this: http://www.bhphotovideo.com/bnh/con...s&Q=&sku=323324&is=REG&addedTroughType=search ), then you need to get one. You will more then likely still get some motor noise from the mic since it is much closer to the tape drive then your subject (directional mics still pick audio from all directions, just less db of it at certain frequencies). But using a shockmount is critical in any shotgun mic situations and will reduce a lot of noise you would get if you don't use one.

Good luck
 
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