[Top] [All Lists]

Re: Phantom Power. Question from The Ghost Who Walks :-)

Subject: Re: Phantom Power. Question from The Ghost Who Walks :-)
From: "Randy Perretta" first_avatar
Date: Sun Jan 3, 2010 7:25 am ((PST))
Very well put Scott and a good synopsis of the state of the art past and pr=

One caution here - A lot of phantom power these days is supplied by cheapo =
(read noisy) DC to DC converters in battery operated preamps and computer i=
nterfaces. The 48V figure can often be a euphemism as well. YV (not M) MV f=
er sure. They get away with it for users who are recording music, especiall=
y electric, but faint, distant bird calls usually don't come with buzz or n=
oise of their own and anything present on the 48V can be objectionable...

If you are going to use the phone line, I'd shield it and toss in a couple =
of caps at both ends.  Order up a hunk of that Mogami double center conduct=
or cable if you've got a extra few bucks or put it on your Valentines day l=
ist.  No, I can't vouch for the efficacy of that but I'd do it out of princ=
iple and just for the fun of the project if I was of a mind to and it would=
 only help I suppose.

Gotta admit, I never thought of that one but I live off grid and phone is a=
 mile or so away.


--- On Sun, 1/3/10, Scott Fraser <> wrote:

> From: Scott Fraser <>
> Subject: [Nature Recordists] Re: Phantom Power. Question from The Ghost W=
ho Walks :-)
> To: 
> Date: Sunday, January 3, 2010, 7:13 AM
> <<One of the things I don't
> understand is how the range of voltage for=A0
> Phantom Power can vary between 9-52V DC and whether the
> voltage=A0
> difference makes an "audio" difference.>>
> Officially Phantom power is 48 volts DC, but in the past a
> number of=A0
> lower priced mixing desks didn't bother to incorporate a
> power supply=A0
> providing a 48 volt tap in addition to the + & - 12 to
> 18 volt rails=A0
> needed for the circuitry. They started supplying Phantom
> voltages in=A0
> the range of 24 to 36 volts, which many condenser mics are
> happy with.=A0
> Neumann mics specifically (I know from personal experience)
> will not=A0
> operate at less than 48 volts without seriously compromised
> dynamic=A0
> headroom, but the makers of the less than fully pro desks
> gambled that=A0
> their end users would likely not also be using high end
> microphones.=A0
> Today it's quite rare to find less than 48 volts available
> on any mic=A0
> preamp. Generally speaking most mics will exhibit higher
> self noise &=A0
> reduced dynamic range when powered by less than 48 volts.
> Electret=A0
> condensers are usually less affected, since the Phantom
> voltage is=A0
> only running the impedance converter circuit, not
> polarizing the=A0
> diaphragm. Generally electrets running on an internal 1.5
> volt battery=A0
> are rather noisy because they are designed to hit a low
> price point=A0
> resulting in a number of design compromises.
> Scott Fraser
> ------------------------------------
> "While a picture is worth a thousand words, a
> sound is worth a thousand pictures." R. Murray Schafer via
> Bernie Krause
> Yahoo! Groups Links
> =A0 =A0 

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the naturerecordists mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU