It doesn't have to
some mics are happy even with just 12 volts and I think T power IS 12 volts

Sennheiser have been doing this a long time and so my gut feeling is that you will be fine if the 15 volts is measuerd at the mic.

However all my desks have 48V and my only experience with low phantom volts or T power is with News gathering equipment (ENG). It's built to work that way

$ .02

you would lose both sensitvity and frq response... better to stick with 48V

Re: $ .02

dementedchord wrote: you would lose both sensitvity and frq response... better to stick with 48V

BUUUUUUUULLLLLL CRAAAAAAPPPPPPP!

Not so.

The standards for phantom are 12, 24, 48 and 52V. There are only a couple that use 52V (B&K, now DPA). Most lowend mixers that specify "phantom" power only, with NO V, are generally NOT 48V. Most other pro mixers specify 48V.

As for mics, mic manufactures generally list the highest, the lowest or a range of acceptable phantom power. It is not selectable by the end user. The mic draws what it needs, and that is it. Since there is no standardization for mic specs....just know that most mics don't need the full 48V.

$ .02

actually the high end B+K's as was discussed in a recent thread use a bias of 130V and i dont think they do it for shit's and grins... (as a point of clarification i could'nt remembeer the exact voltage but had thought it to be in the 150 range but someone else provided the correction) let's remember we're dealing with a capacitor and for any given movement the output would have to be proportional to the voltage on it....YMMV

You do not understand how a DPA4000 system works.

The 130V is NOT phantom power (polarization of the diaphragm). The voltage generated by their power supply, powers the preamp circuit. Their diaphragms are pre-polarized. You should go to their site and read how it works.

DPA DOES offer phantom powered mics.

$ .02

i'm generally pretty secure in my knowledge but never said i knew everything... and thanks for the suggestion on checking the DPA site... is it possible we both have at least some misunderstanding???

from that same site: under "microphone university"

"As DPA has developed a technology using of prepolarized microphone capsules with a *high polarization voltage*, the microphones are not dependent on the phantom power for polarization ...."

are they saying it's an electret??? sounds like it to me...
and are they saying that the phantom on the board/pre is obviated by the use of their supply/pre??? sounds like it to me....

"HMA5000 - not only a comprehensive PSU
The HMA5000 is a dual-channel microphone amplifier with a built-in power supply for both 130V preamplifiers, *200V cartridge polarization* and even 6V heaters..."

gee.... looks to me like the voltage is even more than i thought.... no???

again i never said i knew everything and am looking foward to learning more... and intend to dig alittle deeper on the subject and have you to thank for a good start... need to know more about freq response/sensitivity as relates to capsule voltages...

BTW my original observations were based on a repair of a allen and heath gl4000 (think it was a 4000) guys complaint simply his sm81's were sounding dull and low output... only thing i found was a nasty regulator for the phantom... the artist never noticed and the tour continued....

The description of the HMA5000 is showing it's diversity in function, not the requirements of the DPA4000. Call em' up.

$ .02

the first quote was to the mics in the 4000 series... the second was to the pre/supply that they market as a "suggested" to be used with and was included in my post to point out the 200 volts they put there because you dont need it... whatever...

I forgot to address this fellers. Demented brought up phantom power issues with a console. The friend of his noticed dull sounding 81s. First of all, I would right off those mics, because they are brash and never dull. Second, phantom in ANY low end or mid-level console is going to be questionable. If you measure every channel, with the console on a circuit properly supplied with AC, and then not (which is in reality how most people opperate them), you will find swings in voltage. So, I would not question a mic, but rather the quality of the power supply.

Also, many mics use batteries (CAD, etc) along side the phantom power. Some use the phantom for other things like lighting up the mic. Some cables with lights (Peavey) use phantom. Some use the phantom to power a preamp circuit and have a prepolarized magnet. So, there is nothing to debate further about high V vs. low V mics. Higher voltage doesn't necessarilly mean better performance. You must compare apples to apples.