Using a monitor.

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Howki
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Joined: Jul 1 1999

One irritating problem that has bugged me for a long time is to do with using a monitor.

When we make a movie I much prefer to use a monitor so as a director I can see what the audience will see.(Sort of!)

The problem is that with most monitors I get a hum if the camera is using an external microphone.

I have tried this with many different camerers (camcorders), and with different monitors. I have tried different screened leads, checked for earth loops .Etc.

The only monitor to give me no trouble is a Sony 14inch TV.

I currently use my Panasonic DX1 with a Panasonic 10inch TX G10. It is fine with the Camcorders on board mike but hums badly whenever I use an external mike. (which i usualy do).

Anyone got any suggestions?

Howki

Howki

Alan Roberts at work
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Joined: May 6 1999

Ok. I get the same problem, but it's nothing to do with the monitor.

I have a Pan DX100. The built-in mic is a multiple capsule, giving stereo with a reasonable image width. Any external mic gives low frequency rumble. The problem is pickup of the motor noise from the camcorder. The built-in mic has a cancelling unit in the capsule, and that isn't available in the external mic.

Since the noise is mechanical, there are two possible solutions:

1 - mount the mic away from the camera (i.e. not touching it or anything that it touches).

2 - increase the weight of the mic (plasticene is good, a big dollop) to lower the resonant frequency of the coupling.

I've used both approaches successfully, my favourite is 2 because onlookers always want to know why there's half a pound of plasticene stuck to my mike.

Hope that helps.

------------------

Howki
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Joined: Jul 1 1999

Thanks for the suggestion but I don't think that is the problem. I have the mike on a long boom several feet from the camera. I get the same hum as I do with the external mike mounted on top of the camcorder.

I have a hunch it is all to do with matching (or non-matching) impedances.

I guess I will have to contact Panasonic though this is not a problem peculier to their equipment.

Howki

Howki

Alan Roberts at work
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Joined: May 6 1999

Fine, then another suggestion. I had a problem like this when trying to monitor (on a 14" tv) what I was recording and solved it just by earthing the whole system. I took a 13amp mains plug and mounted a BNC socket on it, connected to the earth pin. I routed the video from the camera to the tv via this connector, using a standard T adaptor. All the hum went away. I suspect it came from using domestic kit that has no real earth connection, relying on double insulation for safety. Nailing a real earth onto the system fixed it in one.

Howki
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Joined: Jul 1 1999

Alan, I owe you one. I put a meter from the earth pin of my Sony 14 inch to the outer of one of the coax sockets and got a reading.
I then started to do the same thing with my Panasonic G10 and found the earth pin in the mains plug was made of plastic!!!

Following your suggestion I connected and wire from the eath terminal in a 13amp plug and connected it to the outer of one of the many sockets on the back of the G10 and Bingo, no hum.

Having paid around £280 for the G10 I was getting a bit niffed with not being able to use it as a monitor though it works great in my editing set up.

Incidentaly, I assume most people use an external microphone when carrying out interviews or taking a scene in a movie. How much does Mr Average pay for the mike? (I know the Pro's spend huge amounts but I am sure the average amateur does not).

How about radio mikes, what experiance has anyone had with these?

Howki

Howki

Phil Becque
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Joined: Aug 3 1999

You might want to look at this web site

http://www.core-sound.com/lcmics.html

I have not tried these yet but I will soon. They were recommended by David Morton in CV a while back and they are low cost - not radio though. Otherwise CV recommended some mics a while back - Sennhieser I think.

Rgds . Phil

Howki
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Joined: Jul 1 1999

Thanks for the suggestion Phil, I will have a look at that sight.

The reason I asked about radio mikes was that before I retired I spent several sessions with a pro group making some company promos. One of the sound recordists (with his case of £800 worth of microphones!) told me that he avoids radio mikes at all cost because they picked up all sorts of unwanted interferance.

It seemed to me that with so many sold they couldn't be all that bad. I have spoken to a few people who have used them and they all said the cheap ones are a waste of time.

I fancy getting one (or two!) but don't want to spend a lot of money if it is going to be a big let down.

Normally we use a mike on a boom with a good wind gag on it,(the mike that is not the boom). One tip here is to make sure the cable is well securred to the boom and that the operater keeps his/her hands still otherwise the noise is awfull.

Howki.

Howki

Alan Roberts at work
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Joined: May 6 1999

I was going to use a radio mike on a shoot last year, but went back to concealed lapel mikes when I was told that the main speaker had a heart defibrillator installed, and was worried that it might interfere (the mike with his heart, I didn't much consider the other way). It's always useful to have at least two ways of doing things