> But this is only half the efficiency picture, don't forget, if using 48 V=
> Phantom power from a recorder, this 48 V power has to be generated by
> another circuit in the recorder ahead of the microphone by using an
> inverter to raise the 5-6VDC recorder battery voltage to 48 VDC so in
> truth, you have a double efficiency whammy, first in the recorder
> generating the 48 V to send sdown the cable, and then in the microphone t=
o
> regulate the 48 down to 5 volts or less, sometimes 3 VDC to power the mic=
> preamp...
>
> Why do we endure this double whammy? Because of cable loses, by sending a=
> high voltage down the cable and regulating it at the mic end supposedly
> overcomes long run cable loses...
>
> Hence for the sake of efficiency, it is far better to have a battery/powe=
r
> source at the microphone as I see it and eliminate the double conversion=
> process which is more battery hungry that the recorder itself... And thi=
s
> proves true according to my own experience...
Hi Mitch,
Yes, the entire phantom power concept is a bit silly in terms of efficiency=
. In addition to that, the required DC/DC converter in the recorder also in=
volves the risk to introduce additional noise.
Another way to prevent this waste of power would be to use a separate power=
supply rail from the recorder to the microphone. This would however requir=
e to establish a completely new microphone wiring standard, which is probab=
ly illusionary and only possible in dedicated recording systems that don't =
need to care about standards.
I have realized this alternative concept in the Avisoft-UltraSoundGate reco=
rding system (http://www.avisoft.com/usg/index.htm), which allows to power =
a 12 microphone recording system entirely from the USB port of a computer (=
500 mA at 5V).
Regards,
Raimund
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