Shotgun mics with dual power

[whyseye]

Since so many voiceover studios (home and otherwise) like to use shotgun mics for promos & movie trailers, I've been looking at adding one to my locker at some point, and been checking them out online.

Some of the shotguns have dual power sources - phantom power or battery. So how does a mic that runs on one 1.5v AA battery also run on 48v phantom power (or vice versa)? What is compromised going one way or the other? I think it was an AT(835? - approx $250-300 new) that brought the question to mind.

Since I wouldn't be using the mic on a video camera, and would most likely run it through an MAudio DMP2, I should have no problem with the phantom power issue, but the more expensive mics are phantom powered only (no battery option), so I'm guessing that there is a reason.

Couldn't find any answers in older threads.....anybody?

 

[crazydoc]

Purely conjecture on my part:

The dual power mics use electret condensers that are prepolarized and so don't need a polarizing voltage applied to the membrane. The battery voltage is used to power the electronics of the mic's headamp, either as is or with a dc/dc converter. If they use 48v, the voltage is converted to the proper level in the mic with a simple resistor/zener divider or the like.

The 48v phantom power only mics could be either electrets or true condensers that apply the voltage to the membrane itself. These mics are likely designed more with professional recording uses in mind, and therefore may be of better quality and more expensive.

I don't know that one would necessarily be better than the other in theory, as current technology produces some good quality electret mics. However, the electrets tend to lose their charge over the years (or so I am told) and so the response could deteriorate, though I don't know how significant this is.

 

[paddyponchero]

Since so many voiceover studios (home and otherwise) like to use shotgun mics for promos & movie trailers, I've been looking at adding one to my locker at some point, and been checking them out online.

Some of the shotguns have dual power sources - phantom power or battery. So how does a mic that runs on one 1.5v AA battery also run on 48v phantom power (or vice versa)? What is compromised going one way or the other? I think it was an AT(835? - approx $250-300 new) that brought the question to mind.

Since I wouldn't be using the mic on a video camera, and would most likely run it through an MAudio DMP2, I should have no problem with the phantom power issue, but the more expensive mics are phantom powered only (no battery option), so I'm guessing that there is a reason.

Couldn't find any answers in older threads.....anybody?

With the audio technica mics running on phantom you get more headroom - the mic will handle higher spl and has larger dynamic range - audio technica lists the specs for both battery and phantom power

http://www.audio-technica.com/prodpro/profiles/AT835b.html

I havn't had experience with the shotgun mics but the AT853 mics I had were had a significantly hotter output on phantom power vs battery.

[Edit]
Oh a further thing to note is that with a 1.5V battery a balanced output would probably require a transformer or some kind of DC - DC converter as these would be difficult to miniaturise and expensive I'll bet that most of the battery powered ones don't have a truly balanced output or utilise a cheap transformer that adversely affects the sound.

 

[whyseye]

I don't know that one would necessarily be better than the other in theory, as current technology produces some good quality electret mics. However, the electrets tend to lose their charge over the years (or so I am told) and so the response could deteriorate, though I don't know how significant this is.

Actually, quite significant to me, since with my current situation I am always on the lookout for used equipment.

Translation......I have chronic gear lust and no budget!

It's been the same for me with camera equipment......but at least with that stuff, I know what to look for, and what the market really looks like.

Every now and then, in a pawn shop or used equipment dealer you come across a little jewel at such a reasonable price you can't help but snag it up, and see if it fits a particular need. If so, you're pleased - if not, you haven't lost a lot and can probably resell it.

So, with that in mind, what looks like a deal on an old piece of gear may not be such a great investment in that case, unless it can really be checked out before purchasing.

So thanks for that tidbit!

 

[ittam]

Voice-overs W. shotgun

I recall it was a famous Hollywood sound recordst who started this overhead
and shotgun practice to imidate practices of the original recordings from the field... It was done mostly with Sennheiser mkh 415/416, short shotguns, and similiar practices could match the picture nowadays also but voice-over is a different thing or spectre or... ADR and Voice over -You tend to want have different timbre on those. Regards Matti

 

[whyseye]

I recall it was a famous Hollywood sound recordst who started this overhead
and shotgun practice to imidate practices of the original recordings from the field... It was done mostly with Sennheiser mkh 415/416, short shotguns, and similiar practices could match the picture nowadays also but voice-over is a different thing or spectre or... ADR and Voice over -You tend to want have different timbre on those. Regards Matti

Do you mean different mic technique?

Yeah, it's a whole different delivery and "address"