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Listening Room
Choosing a Centre Speaker
There is a widespread suspicion
among (possibly) paranoid
consumers that surround
sound was, all along, a plot
to sell more speakers. And there has
been plenty of resistance. DVD players
can feed a two-channel system, after all,
with or without a subwoofer. And even
in full Pro Logic surround systems, you
could do without the centre channel, by
simply selecting “ghost” centre. In many
cases, Pro Logic actually sounded better
that way.
Some 5.1 channel systems can also
run a phantom centre, but in most
cases you’ll be missing something. A
centre speaker now looks pretty much
unavoidable. How important is it? Try
unplugging it on a 5.1 channel system,
and you’ll probably notice that no one is
saying a word. Important? It may be the
most important speaker of the five.
And don’t be misled by the fact that
its main role seems to be to reproduce
voices. The fact that cassette tapes are
often classified as “voice” or “music”
quality has always suggested that
reproducing the human voice must be
a piece of cake. It isn’t. Not only does
the human voice have an astonishingly
wide range, as opera fans know, but of all
the musical “instruments,” it is the one
most familiar to us. We may hear live
bassoons, double basses and guitars only
now and then, but we hear live voices
many times a day.
Two more questions before we move
on to the tests themselves.
Must the centre speaker be of the
same brand as the two other front speakers?
Ideally sure, why not? Is it essential?
Well, the central channel, as noted, carries
mainly voices, which is why it is often
referred to as the “dialog” speaker. Most
modern film sound tracks are mixed with
nearly all of the dialog in the centre, with
Got home theatre?
Got SACD surround?
One of your speakers
will be front and
only a few “off screen” voices sent to the
left and right front channels, or of course
to the rear. Insofar as the centre speaker
is handling material different from that
handled by the others, exact matching
is not important. Still, some filmmakers
will pan the dialog across what is
expected to be the width of the screen.
That means a voice may be reproduced
by both the centre speaker and one of
the other front speakers. And some older
films contain actual stereo dialog. Ah,
the good old days!
But a speaker of the same brand, or
even the same model designation, is not
necessarily a speaker that sounds the
same. The main channel speakers are
designed to be tall and narrow, to place
the tweeter at approximate ear height,
and to afford optimum stereo imaging.
Centre speakers, on the contrary, are
made wide and low, so that they don’t
hide the screen. In many cases the two
are of radically different design. Even
in cases where the centre speaker is
simply the main speaker turned on
its side, the acoustical placement will
pretty much guarantee that it won’t
ULTRA HIGH FIDELITY Magazine 31