Stewart Pinkerton wrote:

It may seem like overkill, but given the amount of signal going to
the centre channel of a 5.1 soundtrack, there is logic to having a
'6.1' system with *two* centre speakers, which can then be placed
close to the sides of the TV, giving both additional power handling
and a more symmetrical appearance.

Finally got news access back, it all seemed to stop working...

If the system's set up correctly, and the speakers correctly matched for
level, tonal balance etc (so basically you're using the same make and
range of speakers across the front) you shouldn't notice a huge
difference between "normal" and "phantom" mode when sat in the sweet spot.

Setting the centre to "wide" (which in this case refers to frequency
response of course rather than aspect ratio) will generally result in a
reduction of what I generally refer to as "high bass", which is the LF
component that your main speakers handle until the sub takes over. Or
the kind of raucousness you get from your average ghetto blaster.
Unless, of course, you have a centre speaker the size of a coffin (seen
a few like that at hi-fi shows) which can produce earth-shattering bass
in its own right.

However, if you're not sat in the sweet spot, the centre makes a lot of
difference, and really improves the imaging. There's actually a centre
speaker fitted in my car at the top of the dash (and probably yours too,
I think the A3 has it as well as the A4) which is fed from the L+ and R-
front speaker terminals. As the amp in the head unit is normally
bridged, this will effectively give you a (L+R)-(L-R) signal. It's then
dropped by around 3.5dB so it doesn't cause a narrowing of the stereo
image. The result is subtly effective, vocals appear to come from the
centre of the dash rather than from the door, without resorting to
time-alignment style tricks.

The centre on my Arcam AVR-250 has a similar mode of operation in the
Music DSP mode, again, reduced by around 3.5dB to avoid narrowing
effects. And it does mean that vocals come from the centre wherever you
are in the room (as long as you're within the perimeter of the the
speakers of course).

As for 2 centres... back when I had my old Yamaha DSP-A592 (which had a
facility to connect 2 centre speakers) the manual recommended that if
you were planning to use 2 centres you should place one above and one
below the screen, NOT one either side. Otherwise you'd lose the whole
point of having a centre speaker in the first place, which is to have a
point source coming from the centre of the screen.

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

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