Don't mean to be argurmentative, but I have never, ever seen any RCA ribbon mic with a grounded
center tap(including 44A's, PB90's & all the way back). What IS grounded is one end of the
primary side of the transformer, because the mic frame is generally used as the return path for
one end of the ribbon. This is not a problem for phantom, however. What damages the ribbon,
as has been mentioned, is the thump created by unbalanced feed resistors, and also by poor
quality cables or connectors.
No ribbon mic, other than those with active electronics, are truly "phantom safe". It's just
some mics are more sensitive to phantom thumps than others. This has to do with factors like
the turns ratio of the mic's transformer, ribbon size, thickness & corrugation type, and magnet
strength. Basically, the more efficient that a ribbon mic acts as a speaker, the more prone to
phantom damage it will be.
And I have personally seen stock Beyer ribbons damaged by phantom.

--
Stephen Sank, Owner & Ribbon Mic Restorer
Talking Dog Transducer Company
http://stephensank.com
5517 Carmelita Drive N.E.
Albuquerque, New Mexico [87111]
505-332-0336
Auth. Nakamichi & McIntosh servicer
Payments preferred through Paypal.com
"Mike Rivers" wrote in message news:znr1088681345k@trad...

In article
writes:

I have a ribbon mic I'd like to gig with, and the PA systems we use
normally plug into have an all-channels-on/off for the phantom power.
Our vocalist uses a condenser mic, so she needs it on. If the phantom
power hits my ribbon mic, it might permanently damage the ribbon
element.

The factoid that a ribbon mic will be permanently damaged by phantom
power is true if the microphone has an internal transformer with a
grounded center tap. Older RCA ribbon mics (the Model 44 for sure,
perhaps others of the era) had this arrangement because they found
that in some cases, it reduced hum pickup.

Unless you got an RCA 44 from a collector, chances are any 44 that
you'll find now will have that center tap lifted and the mic is not at
risk as long as you don't connect it with a cable that's shorted
between the shield and one of the conductors. This is the reason for
the suggestion that you check for conductivity between pin 1 and each
of the other two pins. If it's near a short circuit, there's probably
a center tapped transformer. If it's near an open circuit (a few
megohms, typically) then your mic is safe.

Modern ribbon mics such as those from Beyer and Royer are all "phantom
safe" (I have no idea about the modern Russian mics) but it's still a
good idea not to hot-plug them, but to connect all the mics and then
turn on the phantom power.

It's good to be concerned, but the solution may be simpler than you
think. Of the proposed solutions, I'd go for the isolation transformer
or capacitors rather than fussing with an outboard power supply for
the condenser mic. Some day you might have two condenser mics, or
five, and will have to solve the problem all over again.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo