T-Power vs. 48V phantom power

[Greg Bellotte]

we used to see a lot of t-power in broadcast, basically because the cameras of old only supported t-power on the mic inputs, so thats what was purchased to go on camera. most broadcast cameras today support both types of power, so we see more p-power since both the cameras and audio consoles support it. neither type of power affects the audio quality that the mic produces. as mentioned, differing powered mic models are still the same mic after all, only the powering scheme is different.

one issue against t-power is the fact that there IS a serious voltage potential across the audio circuit. normally not a problem, but in tournament golf coverage, where your mic cables sit overnight on the golf course while the sprinklers run, dampness that developed in the cable can start to cause tiny shorts which sounds like frying bacon or static in your audio. most users will NEVER have that problem, but it caused me to recommend replacing about 50 t-powered mics with p-powered versions a few years back. then we had issues with a certain external p-power supply and now p-power directly from inputs when possible. as with anything in audio, one mans dream can be another man's nightmare...

personally i like p-powered stuff, it just seems to be a little more universal and more resistant to the wet cable issue (sadly an ongoing concern on my shows). however over 20 years with both types says either one works great, as long as you are matching power type to mic type.

[Carlos E. Martinez]

This is a very old topic, and let's hope someone still reads it.

If I remember well the Nagra used -10v on their T power, because the whole power for that recorder was wired that way. The ground was positive, not negative. You had to rewire the T mics or the cables you were going to use with the Nagras.

[Brian Drysdale]

I think a lot of people just changed the Nagra wiring to match the standard. They also had male connectors so you had to make jump leads to convert them to female XLRs..

[Bruce Watson]

Originally Posted by Steve House

In a nutshell mic power is aq DC voltage sent to the mic on the same cable that the audio comes back on. A balanced line has signal hot, signal cold, and a ground conductors. T-power puts the 12v DC across the signal hot and signal cold conductor, ground is neutral. Phantom puts DC across both of the 2 signal conductors together and the ground conductor.

If you connect a dynamic or a ribbon mic to a cable carrying T-power, current will flow through the mic capsule, potentially damaging the dynamic mic and almost certainly destroying the ribbon mic. But with phantom, since signal hot and signal cold are at the same positive DC potential, no current flows and the chance of damage is much less. The relative safety from accident mic damage is one of the key reasons phantom has largely replaced T-power.

Nicely said. It's an old thread, but I hadn't read it; nice to see the good information out there!

[Carlos E. Martinez]

Originally Posted by Brian Drysdale

I think a lot of people just changed the Nagra wiring to match the standard. They also had male connectors so you had to make jump leads to convert them to female XLRs..

No, only European Nagras had XLR male connectors at the input. All Nagras I used female XLR input.

Europeans also used a screwable connector on the mic sometimes, very uncomfortable.

People re-wired the mics usually, to use with the Nagra, which was the most popular one.

[Brian Drysdale]

The Nagra agent modified the wiring on mine and the impression I got was it was pretty common.

[Richard Crowley]

In another generation, nobody will even remember what "T-power" was. They will have to look it up on Wikipedia or something as if they were seeking information about the Battle of Hastings or some other arcane topic.

[Brian Drysdale]

I've got an adapter unit that converts P48 to T power, it just plugs into the cable like a male to female converter.

[Carlos E. Martinez]

Yes, I have that adapter too for my T - 416, and it works quite well.