--- Forwarded Message from Bob Majors <[log in to unmask]> ---

>User-Agent: Microsoft-Entourage/10.1.1.2418
>Date: Wed, 04 Jun 2003 14:43:13 -0700
>Subject: Re: #7169.1 mixer with 5 V DC (!)
>From: Bob Majors <[log in to unmask]>
>To: Language Learning and Technology International Information    Forum   <[log in to unmask]>
>In-Reply-To: <[log in to unmask]>

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>> From: Derek Roff <[log in to unmask]>
> I wonder if a standard mixer with Phantom Power for microphones would
> work.  We have used Mackie, Behringer, and Nady mixers with various
> power-needing microphones.  As I remember it, the mics specify 1.5,
> 5, 12 and 48 volts, or Phantom Power mixers.  I find this voltage
> variation mysterious (hence the name "Phantom"?).

Phantom power supplies DC voltage from about 11 or 12 VDC up to 48 VDC.
Quoting from the rane source below:

"Most condenser microphones require phantom power in the range of 12-48 VDC,
with many extending the range to 9-52 VDC, leaving only a very few that
actually require just 48 VDC. The reason is that internally most designs use
some form of current source to drive a low voltage zener (usually 5 volts;
sometimes higher) which determines the polarization voltage and powers the
electronics."

Phantom is supplied on two pins of a balanced audio path, and my experience
with it has always been with balanced audio (3-pin (XLR)) mics, so I'm not
sure if or how you'd rig it for a tip-sleeve (hot-ground) mic if that is
what the headset is.

http://www.rane.com/par-p.html

http://www.shure.com/support/technotes/app-phantom1.html

http://www.sounddevices.com/tech/phantom.htm

As for use of the mixers listed above, they'd all do fine (and Behringer
even less expensive), but are overkill unless money is no object.  For their
cost, one could potentially upgrade to OS X whose core audio doesn't suffer
the poor latency of OS9's sound manager.

Bob