On Thu, 10 Aug 2006 08:57:55 +0100, "Dave Plowman (News)"
wrote:

In article .com,
wrote:
While a single Power Humpty can run the entire unit, you
can use a second Power Humpty for true dual mono operation.

Presumably only if each is driven off its own mains generator?

Blah Blah Blah with you guys and your techno wank.

If two separate power supplies are needed for 'dual mono' whatever that
is, it simply means the designer can't make a decent single one. Or more
likely is buying in poorly designed cheap ones. Or perhaps you think
something like a mixing desk used in a radio continuity where there will
be all sorts of signals incoming that you wouldn't want to break through
uses one power supply per channel? Etc.

It so limits your ability to be opened minded and trust your ears.

The 'ears' unfortunately are easily fooled by the 'brain'.

I would expect signal-to-supply coupling to be somewhere around -80dB
in a decent design. If you then move over to the victim side, I would
expect a competent design to have around another 80dB of PSRR. That is
a total isolation of 160dB, which is certainly going to be swamped by
airborne stuff however good the power supplies are.

So no, there should never be a need for separate power supplies.

As for dual mono. That clearly means separate programme material in
the two amplifiers - otherwise it would be stereo. If you are
amplifying different material, presumably you are going to have them
in different rooms, so separate power supplies are pretty much a
given.

d

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Pearce Consulting
http://www.pearce.uk.com