[sdiy] +48v

[Magnus Danielson]

From: "J.A.Hurt" <prospective_volition at hotmail.com>
Subject: [sdiy] +48v
Date: Sun, 15 Jul 2001 18:09:26 +1200

> Hello, anyone know of any schematics for a +48v phantom power supply?.

The simple "classical" method is to drop the +48V onto the + and -
terminals through a pair of 6.8 kOhm resistors and DC block in the
signal path using a pair of 10 uF electrolytics. This passive method
has the benefit of simpleness, which is really good when you do alot
of them (think big mixer console). On the downside we have the use of
electrolytics in signalpath (I wont bore you with the details - it is
just bad) as well as the HP action of the RC (6.8 k * 10 uF = 68 ms =>
2.34 Hz).

A better method is to use an isolational transformer. The upside of
that is the much lower HP cutoff but the downside is weigth and cost.

There are other possible means of acheiving the DC blocking but I
can't recall seeing any others in use.

Cheers,
Magnus - helps you to keep the world balanced