Subject: Re: [linux-audio-user] recording guitar interfacing
From: Jörn Nettingsmeier (nettings_AT_folkwang-hochschule.de)
Date: Thu Nov 29 2001 - 21:49:21 EET
Steve Harris wrote:
>
> On Thu, Nov 29, 2001 at 04:09:00PM +0100, Tobias Ulbricht wrote:
> > So any mixer that provides these "mic" inputs (usually they are, say track
> > 7 and 8 of the 8-track-mixer??) provides the 48V DC current?
> > And still I could use these plugs for, say recording another two guitars
> > (on top of the other 6 guitars on the remaining :) savely? Meaning the
> > "phantom power" doesn't do any harm to any other audio source....?
>
> Phantom power is onnly provided on the 3 pin XLR inputs and it is usually
> switchable, though it may not be switchable per input, it might be in
> blocks.
>
> Plugging ordinary mics into sockets with phantom power on is *bad*.
not necessarily. modern symmetric mics don't "see" the voltage at
all, because it is applied to both the (+) and (-) connector. so
there is no current through the pickup coil.
of course there are some really cheap mikes that connect one end to
either (+) or (-) and the other to ground.
in this case, it's possible to blow them, although the current is
not that spectacular:
48 volts / 600 ohms or so for a dynamic mike = 0.08 ampere.
condensers have an infinite dc resistance, at least in theory, so
they won't be harmed at all.
watch out with vintage gear and home-made adaptors, but your
standard sm-58 takes phantom power without a blink.
-- Jörn Nettingsmeier home://Kurfürstenstr.49.45138.Essen.Germany phone://+49.201.491621 http://spunk.dnsalias.org http://www.linuxdj.com/audio/lad/
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