Thanks for the update on condenser mic technology.  Also, thanks
for your discription of the 3.5 MM cell phone connector.  That,
by the way, is what Raspberry Pi's use for their audio and analog
video output jack.  That jack will usually work fine if you plug
in a stereo headphone pair but if there is the slightest bit of
slop, you'll hear video buzzing away in one of the channels.

	Are there breakout cables for those 3.5 MM connectors?

	I can imagine 3 2-conductor plugs on the other end.  All
3 would share the ground and each tip would be one of the three
hot conductors in the 4-conductor male plug.

Martin WB5AGZ

Colin McDonald <[log in to unmask]> writes:
> Nice description.
> I believe that voltage is 3 or 5 V on the computer mic jack.
> If you want to get even more crazy, the 3.5MM plugs for cell phones is a 4
> conducter plug with 2 rings and a sleeve.  These are for the phone 
> headsets
> that carry mic audio and audio from the phone.
> 
> Pretty much all pro audio line mixers have fantom power these days, even 
> the
> small 2 or 4 input mixers have a 48V switchable fantom power source.
> The higher end mixers will have a 48V switch on each channel strip. some
> have switches to apply 48V to groups of 4 XLR inputs on the mixer.  The
> majority have 1 on/off switch for 48V usually located next to the main 
> power
> on/off switch.
> Back in the days when the T-rex roamed the earth, and ferns grew aplenty,
> and neanderthals were just a twinkle in someones eye, and when the earth 
> was
> still round and not flat hi hi, pro condenser mics used batteries because
> only a few models of very high end mixers had 48V on the XLR jack.  You
> could and still can get 48V power supplies that can be inserted into the 
> mic
> line to provide the fantom power to the mic.  But, with todays mixers 
> having
> 48V as a pretty standard feature, those boxes are far less important.
> The old classic Neuman and Telefunkin studio tube mics all used their own
> dedicated power supplies.  Nowadays, they just come as is and you use the
> power supply provided by whatever device you are plugging the mic into
> weather it be a recording interface, mixer or whatever.
> So instead of batteries in the condenser mics running down because people
> would leave them on etc, the audio engineers bain is now wireless packs 
> and
> mics being left on and draining the batteries.
> Some companies are getting pretty good at intelligent circuitry to put the
> devices into stand by when they aren't being used to save batteries, but
> it's still a fight with gear that doesn't have that option.
> Some of the big touring acts like U2 for instance, have 48 wireless packs 
> on
> stage between guitar transmitters and vocal mic transmitters.  Those guys
> don't even mess around, they simply change all the batteries out 
> immediatley
> prior to the show.  The newest wireless tech in the pro audio industry is
> using half the power to accomplish the same job.  In otherwords, packs 
> that
> used to take 2 double A batteries now only require 1.  A high end long 
> range
> FM wireless guitar transmitter say 10 years ago would require 4 double A
> batteries, and the same device now, using totally digital modes needs 1 
> for
> the same range and same use time.
> Thankfully I only have to deal with 4 wireless packs in my band, two 
> headset
> mics and two guitar packs, but even still, I tend to run through double 
> A's
> pretty quickly with at least 8 fresh batteries per show and usually a 
> fresh
> set every 3rd rehearsal or so.
> 
> 
> 73
> Colin, V A6BKX