Re: [LAU] OT: Phantom power and my acoustic guitar

On Sun, 2009-01-25 at 22:51 +0100, Jörn Nettingsmeier wrote:
> Andrea Del Signore wrote:
> > Hi all,
> >
> > sorry for the off-topic post, but since I'm a linux audio user from a
> > long time
> > this is the only audio group that I know ;)
> >
> > My question is: can I connect an Ibanez AW40ECE-NT guitar to a mixer
> > with
> > phantom power switched on? The guitar has a fishman pickup and an Ibanez
> > SST
> > preamp and I'll connect with the mixer using the XLR output, so the
> > connection
> > will be XLR to XLR.
> >
> > Best regards,
> > Andrea
> >
> > P.S.
> > I'm asking it here because searching through the various guitar and
> > homerecording forums I found contradictory responses: someone says that
> > I can
> > damage my guitar pre or mixer and some other that it safe to connect
> > with an XLR
> > cable on both sides ("phantom" power).
> >
> > My mixer manual says only that I can't connect "unbalanced" equipment
> > while
> > phantom power is switched on.
>
>
> that depends on how your cable is wired. i assume that your guitar is
> unbalanced, i.e. it has a 2-pin connection.
>
> phantom power works because pin 2 and 3 of an XLR connection are both
> 48v. if you connect your guitar to pins 2 and 3, both are at 48v
> potential, i.e. no current flows (hence "phantom").
>
> but if you connect your guitar to pin 1 and either 2 or 3, then the 48v
> will cause a current through your guitar's electronics. if its impedance
> is high, no problem, but if it is significantly lower than a few hundred
> ohms, you will get a heat problem and possibly damage your equipment.
>
> both ways of wiring will work, but the 2/3 scheme requires balanced
> inputs, otherwise you will hear nothing.
>
> the mixer's phantom power should be short-circuit-resistant, so it will
> not take damage even while it's frying your external gear. but since
> most mixers should have a current-limiting resistor in series with the
> phantom power rail, most types of gear should be safe. i wouldn't bet on
> it, though.
>

Hi Jörn,

thanks for your clarifications, and thanks to all the other advises.

So now it's clear to me that all I can do is:

1) Open my guitar electronics and see how is wired :(
2) Just try and hope

By the way I already searched the ibanez site for the preamp manual, but
it doesn't contains any info on phantom power nor it does specify if the
output is balanced or unbalanced.

By the way I ever thought that since the guitar has two output plugs one
XLR and one jack 1/4", the XLR one was balanced while the other
unbalanced.

Best regards,
Andrea

_______________________________________________
Linux-audio-user mailing list
Linux-audio-user@email-addr-hidden
http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
Received on Mon Jan 26 04:15:05 2009