In message , Dave Plowman
writes
In article ,
Ian Molton wrote:
The currents required are quite small. Hence you might find a suitable
box of batteries will be cheaper and simpler than a mains-based
design. Should make it easier to avoid noise and hum problems.

Indeed. When it says '15-48V' does it really mean anything in that
range? if so, the pair of 12V cells someone suggested is probably the
way to go.

Unless you intend long periods of use 4 PP3s should give about 50 hours at
least, although it's very much dependant on the mic. Some older AKG types
like the early 451s are happy on 9 volts - others may need 40+.


On my SSM2017 pre-amp I use two gel-type lead-acid batteries to give me
+/- 12V for the chip, and I then use an isolated dc-dc convertor running
off the total 24V to provide a 0V referenced +30V for the phantom feed.

On the CM8000 the phantom feed is only to power the pre-amp as the mic
cartridge is an electret and doesn't need an external polarising supply.

(On the professional capacitor mics like the B&K 4133 the battery supply
is stepped up to a couple of hundred volts to polarise the capacitor
cartridge).
--
Chris Morriss