More details: http://personal-view.com/talks/discussion/3197/at875r-mic-phantom-powered-directly-by-the-gh2#Item_7

Audio samples: http://personal-view.com/talks/discussion/3197/at875r-mic-phantom-powered-directly-by-the-gh2#Item_11

Which phantom powered mics will operate on such a low voltage? Electret condenser mics (i.e. permanently charged) are good candidates. You'll also want a mic with high sensitivity, to give a high SNR given the noise of the GH2's pre-amps and the quantization noise of 16-bit samples. I speculate that mics that can operate on a low-voltage battery are good candidates. But ultimately you'll have to test the mic to see how well it works. Here's more info: http://recording.org/pro-audio-gear/30016-phantom-power-is-a-mystery.html

How do you wire the mic cable? From my testing, the AT875R can be wired with XLR pin 3 unconnected, or shorted to pin 1, which apparently means it is impedance balanced. Here are wiring references:
http://www.audio-technica.com/cms/site/4ffc7039c199613a/index.html/index.html#unbalancedinput http://www.benchmarkmedia.com/discuss/feedback/newsletter/2008/05/2/helpful-how-tos-how-properly-connect-balanced-outputs-unbalanced-input

You must lose something by operating the mic under spec, right? Generally speaking, the max sound pressure level before distortion will be reduced somewhat, and the sensitivity will be reduced a tiny bit. Judging by the specs of other Audio-Technica shotgun mics that can operate on phantom power or from a 1.5-V battery, the max SPL is reduced by about 10 dB. Even with that reduction, the max SPL is still quite high - so high that if you are in that environment, you better be wearing earplugs. I tested some loud sounds, and I was getting distortion inside the GH2 with the mic level setting set to 1 (the lowest gain setting) before I got any distortion from the mic.

Of course the weak point in any GH2 mic connection is the 2.5-mm jack. I got the highest quality cable with a right-angle connector that I could find, and made my cable just the right length to keep it secure and out of the way. The link is unbalanced, so to minimize interference, use a shielded cable and keep it short.

The GH2's lack of real-time audio monitoring prevents the use of the mic port for any application in which the audio is critical. But you can work around the lack of monitoring to a certain extent. Plug the mic into something that does allow monitoring (e.g. the Zoom H1), and do some walk-around tests to identify problems. I found and eliminated noise coming from my shock mount, cable, and XLR connector. You can also record a short test video and play it back and listen through the GH2's terrible, tiny speaker before shooting.

The shock mount configuration in my photos is intended to have a very low profile. A more standard configuration would put the shock mount higher and allow for the use of wide-angle lenses. But in my configuration the mic is out of the view of all of my lenses, including the Lumix 20-mm. I swapped and reconfigured the elastic bands to improve the isolation and give a slight upward tilt that keeps the mic out of the lens's view.

With the GH2 mic level set to 4 (the highest gain setting), speaking in a normal voice from about 3 feet in front of the mic puts the meter at 7 bars, just into the red.

Compared to the MKE-400, the AT875R has better rejection of off-axis sounds, and the shock mount I'm using performs much, much better than the one built into the MKE-400. I might have been satisfied with the MKE-400, except for its shock mount. Every time my finger touched the camera, you could hear it in the recording.

Where to get mike:

• http://www.amazon.com/Audio-Technica-Gradient-Shotgun-Condenser-Microphone/dp/B000BQ79W0/
• http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1313&_nkw=Audio-Technica%20AT875R&_sacat=0&_clu=2&_fcid=168&_localstpos&_stpos&gbr=1