February 7, 2007 at 2:34 PM #41210
Sony DCR-HC30 MiniDV consumer model camcorder. This camera has a powered mic jack. I measured the voltage at 2.1 vdc. Can anybody tell me why the mic jack is powered? I have recorded with a wired battery powered microphone and a wired unpowered mike and can tell no difference.
February 21, 2007 at 8:47 AM #175360
The 2.1v you are finding from your mic jack is for miniature condensor mics. These have a tiny first stage pre-amp that needs between two and ten volts. These are the type of mics used in many consumer electronic devices such as phones, etc.
These mics are tiny, you can fit one in the body of a bic pen. Some have better specs than others. I bought a couple dozen panasonic mic capsules from http://www.digikey.com after following a forum for minidisc recording enthusiasts. There are hundreds to choose from, but the experts on the minidisc recording forums have strong opinions on which ones give the best results. They are optimized for the type of product they were designed for. The microphone capsules are only a couple of dollars a piece. To get the best results one can use them with a seperate pre-amp. Using 9 volts of phantom power gives better dynamic range with the type I chose.
Lots of people sell these mics on ebay pre-assembled in small housings ready to plug into a powered mic jack. Do a seardh on Ebay using the terms minidisc microphone. Depending on your application and the specs of the microphone, it might give you much better results than the one built into your camcorder.
February 21, 2007 at 8:58 AM #175359
February 21, 2007 at 9:28 AM #175361
I found the following great explanation at: http://www.transom.org/tools/faqs/faq.mics.html#pluginpower
What’s plug-in-power, and is it creating noise on my mic?
Plug-in-power is a small voltage delivered from the recorder to certain electret microphones, it’s similar to phantom power, but the two are not interchangeable. You can’t power a standard condenser mic with plug-in-power, nor can you run a plug-in-power mic from the standard phantom power often delivered by pro recorders or mixers.
So the deal is that if you buy a small consumer level mic, some of which are pretty good, like the Sony stereo mics, or the discontinued little Radio Shack lavaliers, you can plug them straight into your minidisc and they’ll get the required power from the deck. Otherwise you’d need to use an adapter with a battery.
If you want to use a dynamic mic, such as the EV RE50, or the Beyer M-58, don’t worry about the plug-in power, you can ignore it, although the Shure a96f will give you better volume, convert the connector types and shunt the plug-in-power .
If you use a pro condenser mic that needs phantom power, you’ll need to get one that can use an internal battery, or get an external phantom power supply, the plug-in-power will NOT power a pro condenser mic.
There have been occasional reports about "plug-in power" (a small voltage carried on the mic cable, provided by many consumer minidiscs and DAT machines that can supply a needed charge to some electret microphones) creating clicks or noise when using a dynamic microphone. I’ve never found the plug-in power to create any problem, dynamic mics generally don’t react to it. If you get hiss from your mic, it’s most likely just from the relatively weak preamps that were designed to work with high-impedance electret mics that do make use of the plug-in power. Crackles are more likely due to a bad cable or dirty or worn jacks.
So, as we’ve discussed a few times on this site, the Shure a96f will raise the impedance a bit, which will give some more gain, it also shunts-off plug-in power if you’re concerned about it, and it’s a nice simple XLR-to-mini cable with the transformer built-into the XLR jack, so it’s not a kludgey pile of connectors.
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