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-   -   HELP: Killing a Microphone (https://www.dvinfo.net/forum/all-things-audio/48550-help-killing-microphone.html)

Chris Carera July 29th, 2005 08:17 PM

HELP: Killing a Microphone
 
I'm try to shoot a short film with some friends, and we're borrowing all of the equipment we can get. We're shooting on a JVC 5000 series broadcast camera (borrowed from the journalism department), and we were hoping on borrowing a broadcast quality boom mic, but our source fell through.

Instead, we were able to borrow a prosumer electret condenser microphone from someone else. It connects to the camera with a miniplug, but the camera has only XLR connectors. This morning, we were able to borrow a converter, or, rather, two converters stuck together (1/8-1/4 miniplug adapter stuck into a 1/4 miniplug to XLR connector.)

Everything snapped into place comfortably. We tried the mic, and had no luck. We adjusted all of the channel settings, and had no luck. We changed batteries inside the microphone twice, and tested those batteries in a digital camera. They worked.

We then tried the microphone by plugging it into the sound card of a computer. It didn't pick up any sound either.

When I looked back at the camera, I saw that where we plugged in the xlr connector, there were three switch options: line, mic, and mic+45V. I believe that we had it plugged in on the last option, and I'm worried that the 45 volts may have damaged the microphone permanently, and that we now owe our friend a new one.

Is this possible? Probable? Is there anything else we should check for?

Thanks for all your help. This is a great forum, and I've learned a lot here.

David Ennis July 29th, 2005 09:45 PM

Chris, I think you can relax. It's not likely that 45V would hurt the mic. If battery powered XLR mics were designed such that accidental application of standard phantom voltage would hurt them, there would be a lot of fried mics out there. Besides, the hookup you described is a pretty good indication that the mic wasn't even getting the voltage.

Coincidentally, for an explanation of why the mic didn't work, and what to do about it, see the post just below this one (from Scott Brickert) that I just finished replying to.

Ty Ford July 30th, 2005 09:26 AM

Quote:

Originally Posted by Chris Carera

We then tried the microphone by plugging it into the sound card of a computer. It didn't pick up any sound either.

When I looked back at the camera, I saw that where we plugged in the xlr connector, there were three switch options: line, mic, and mic+45V. I believe that we had it plugged in on the last option, and I'm worried that the 45 volts may have damaged the microphone permanently, and that we now owe our friend a new one.

Is this possible? Probable? Is there anything else we should check for?

Thanks for all your help. This is a great forum, and I've learned a lot here.


Applying 48 V DC Phantom Power to an unbalanced microphone can destroy it.

Ty Ford

Steve House July 30th, 2005 11:40 AM

Quote:

Originally Posted by Chris Carera
...
We then tried the microphone by plugging it into the sound card of a computer. It didn't pick up any sound either.
...

I know it sounds obvious, but did you plug a known good working mic into the sound card to see if it worked? You may have a fried mic but then again the mic input on the sound card might be switched off or its gain turned way down. Likewise, how are the camera's audio input settings? Could you have an attenuator in the camera switched on and the recording level turned way down?

Is the plug on the mic a TS or a TRS plug?

David Ennis July 30th, 2005 01:57 PM

Yikes, I didn't catch that it was an unbalanced mic..my head was still in the previous thread. There is still a good chance that you were saved from applying the voltage to the mic by the combination of connectors. If the XLR adapter ended in a three section plug your chances are pretty good. Here's hoping...

Chris Carera July 31st, 2005 06:52 PM

I'm not really sure whether it's a TS or a TRS plug, or whether it ends in a three section plug (I do know that it has three prongs where it plugs into the camera), because I don't have the microphone or adapter with me at this time; they're at a friend's house.

But I'll take pictures of the whole setup, and try testing the microphone on my own sound card (which I know works), and see what you guys think.

Thanks for all the help so far.

David Ennis July 31st, 2005 08:04 PM

Chris, if you can just tell us the make and model of the mic I can tell you what you need to order from B&H or pick up from Radio Shack for about $10 to make it work with the camera. This assumes the mic is still good, which I think the odds favor.

Chris Carera July 31st, 2005 10:31 PM

This is the microphone: the Sima SZM. It's probably not a very good one, but we figured that it would be better than the camera mounted omni-directional mic.

http://www.simacorp.com/products/ite...e173f39&id=481

Stephanie Wilson July 31st, 2005 11:00 PM

Quote:

Originally Posted by Chris Carera
I'm not really sure whether it's a TS or a TRS plug, or whether it ends in a three section plug (I do know that it has three prongs where it plugs into the camera), because I don't have the microphone or adapter with me at this time; they're at a friend's house.

But I'll take pictures of the whole setup, and try testing the microphone on my own sound card (which I know works), and see what you guys think.

Thanks for all the help so far.

Hi Chris,

I put your question to my satellite truck engineer friend. According to him, if the mic was unbalanced and given the particular circumstances you describe; you may have damaged the mic. An unbalanced mic has no transformer and the transformer is essential for providing necessary impedence for the mic.

Also the middle "ring" in a TRS connection is the only way to accept a ground?

What do I know, just passing on what my best friend took the time to address....

My best,

Steph

David Ennis July 31st, 2005 11:25 PM

Well, I spoke too soon, Chris. Even Sima's web page on that mic doesn't reveal whether it has a TRS or TS mini plug on it. We'll have to wait until you get your hands on it again.

Quote:

Originally Posted by Chris Carera
...We then tried the microphone by plugging it into the sound card of a computer. It didn't pick up any sound either...

I'll have to admit that this comment cools my optimism. I didn't catch it the first time. But we can hope.

Chris Carera July 31st, 2005 11:43 PM

In case I have to replace this thing, can any of you help me find a good price for a new one?

I've used froogle and I've seen that B&H doesn't have it, but I'm not sure where else to look, really. I'd like to find it below eighty dollars, which might be asking too much.

Thanks for everything so far.

Ty Ford August 1st, 2005 05:40 AM

Buck up and try the Rode VideoMic. :)

Ty Ford

Mike Teutsch August 1st, 2005 06:05 AM

[QUOTE=Chris Carera]In case I have to replace this thing, can any of you help me find a good price for a new one?

I've used froogle and I've seen that B&H doesn't have it, but I'm not sure where else to look, really. I'd like to find it below eighty dollars, which might be asking too much.QUOTE]

Try this Ebay link and see if it helps you. Mic you are looking for, Sima SZM-2? $23.00 right now, with no bids. Hope that this helps.

Mike

http://cgi.ebay.com/Sima-SZM-2-Zoom-...QQcmdZViewItem

Steve House August 1st, 2005 07:33 AM

Quote:

Originally Posted by Stephanie Wilson

Also the middle "ring" in a TRS connection is the only way to accept a ground?

FYI...
TRS stereo: tip=left, ring=right, sleeve=ground
TRS balanced: tip=signal hot, ring=signal cold, sleeve=ground
TRS unbalanced, equivalent to TS: tip=signal, ring=ground (bridged to) sleeve=ground (TRS jack to TS plug wired like this makes an unbalancing adapter)

and just to make things interesting

TRS on mono mic, compatible with stereo or mono inputs: tip=signal (bridged to) ring=signal, sleeve=ground

Here's an exercise ...

How would you wire an adapter to connect a single, mono BALANCED mic so it could be plugged into a camera mini-jack input designed for a (two channel)stereo mic, disregarding any issues surrounding phantom power?
.
.
.
XLR pin 1 -> TRS sleeve
XLR pin 2 -> TRS tip bridged to TRS ring
XLR pin 3 -> unused or TRS sleeve

David Ennis August 1st, 2005 09:22 AM

Quote:

Originally Posted by Chris Carera
In case I have to replace this thing, can any of you help me find a good price for a new one?

I've used froogle and I've seen that B&H doesn't have it...

If Mike's eBay suggestion above doesn't work out, I got lots of hits on Google under "Sima SZM." The going price seems to be in the $40-50 range. Here's one:
http://datavisioncomputer.com/webapp...7&cgmenbr=2000


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