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.

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.

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

Ty Ford

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?

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...

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.

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.

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

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

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.

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

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.

Buck up and try the Rode VideoMic. :)

Ty Ford

[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

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

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

I believe I have seen that mic in Best Buy although I can't find anything but the MZM-1 on their website.

I bought it in Best Buy. Around $60. It has a TS plug.

Chris, here's the adapter cable you need to efficiently connect that mic to the camcorder. It's available in longer lengths also.

http://www.bhphotovideo.com/bnh/cont...ughType=search

The assembly of adapters that you already have may work too, but I hope not--because if it does it also applied that 45 volts to the mic. The reason it might not is that people often grab from what's available and connect stereo plugs to mono jacks and vice versa. Plus the fact that the 1/8 to 1/4 adapter could be mono to mono, stereo to stereo, mono to stereo or stereo to mono. All this matters as to whether a given conductive path makes it all the way through.

Steve,

I think I know what you're describing but I don't have the guts to respond. But if you are interested in a friendly, fun and intellectual challange, I'll hook you up with the smartest engineer in Los Angeles. He's a great guy and I'm sure you will appreciate each other's intellect.

And most importantly, it may help to educate us all. Look forward to your positive post,

Steph

Always nice to meet new folks. Was just gently correcting you where you said the ring of a TRS connector was "the only way to accept a ground" when in fact it is only grounded in a couple of special circumstances, namely when making up a balanced-to-unbalanced adapter and even then not always, sometimes it's not connected at all. If the TRS is used for a stereo signal such as a pair of headphones the ring carries the right channel signal while if it is used for a balanced mono mic or line level connection instead of an XLR connector it carries the "cold" side of the signal.

A lot of stereo consumer devices like cassette recorders etc, and I'd think that would include a lot of consumer camcorders, have a mic connector that can accept a "stereo" mic. A true stereo mic, two regular regular mic elements in the same handle, is wired like the headphones mentioned earlier with the left mic going to the tip and the right mic going to the ring, both sharing a common ground through the sleeve. A MONO mike intended to be plugged into such a device, which some manufacturers might actually label a "stereo mic", has only one capsule and thus one signal line plus ground. Since we'd usually want to record the same mono signal on both the left and right channels in the recorder, the mic might have a TRS connector that has the tip and ring connected together and so both are connected to the same signal. That way the mono signal is divided at the jack and goes equally to the left and right channels in the recorder. A lot of mics that come with computer soundcards or on computer headsets are wired this way. Over the years I've accumulated a pile of them and when I checked with a multimeter that's how they were all set up