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January 2015
entertainment, presentation, installation
www.lsionline.co.uk
PLUS: Black Light’s Triple Jump • Peavey Streamlines Pro • Venue: Unity Works
Coolux Pandoras Box
• Solotech networks with ELC • Audio File: The Year of the Cat-5
In Profile: LD Andy Hurst
• New Products . . . and more!
Also Inside:
Preview: ISE 2015
Expected highlights
TF: The Shapeshifter
HES’s multi mover assessed . . .
Profile: Stufish
The Entertainment Architects
Sydney Opera House
The iconic venue’s concert hall balances
heritage with cutting edge LED lighting
Paloma Faith On Tour
LSi reports from York Barbican
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LSi - January 2015
40
www.lsionline.co.uk
classicgear
Rob Halliday takes a nostalgic but instructive look back at the tools that have shaped the industry . . .
Sometimes, thinking outside of the box really
does mean doing exactly that. Take the
challenge presented to sound designer
Martin Levan by Andrew Lloyd Webber for the
original Phantom of the Opera in 1986: the
composer wanted the sound to appear to
come naturally from the stage rather than
sounding like a bunch of loudspeakers
around the proscenium. Levan’s solution: to
take the loudspeaker drivers out of their
boxes and use them naked, open, exposed to
the air . . .
It’s one of those ideas that probably shouldn’t
work, yet somehow gloriously did - mainly
because he was using a very particular driver,
already established as a classic in the audio
world, particularly in studio monitor
loudspeakers, but which following Phantom’s
success found a new life in theatre sound
reinforcement: Tannoy’s Dual Concentric Driver.
Most standard loudspeakers, those using
magnets driving cones to move the air and
make the sound, actually divide the audible
frequency range between separate drivers,
each optimised for a different section of the
frequency range, a ‘woofer’ for the low notes,
a ‘tweeter’ for the high ones. Because each
driver is a distinct, separate device each has to
be mounted in a separate location on the
loudspeaker’s front panel. This means that
different sounds actually emanate from different
physical locations on the speaker, and may not
quite be in phase with each other. The speaker
is not actually achieving the hypothetical ideal of
creating one coherent waveform, an exact
reproduction of the soundwave being replayed.
A few loudspeakers attempt to use a single
driver to cover the entire audible frequency
range as a solution to this. Tannoy, founded in
1926 and long a household name for its public
address loudspeakers, took a different
approach. Their Dual Concentric driver,
launched in 1947, still used separate low- and
high-frequency drivers, but the high-frequency
driver was positioned in the centre of the
low-frequency driver, effectively firing through it the bass cone had a hole in the middle to let the
sound through. All of the sound appeared to
come from one point, a coherent, in-phase
wave regardless of the material being played or
the listener’s position.
Of course, in their loudspeaker ranges Tannoy
still mounted the drivers in wooden boxes,
traditional style to load and control the drivers.
The Dual Concentrics were, and still are, used in
their domestic and pro audio speaker ranges,
the latter found in many prominent recording
studios. They currently produce Dual Concentric
drivers in sizes from 4” (100mm) up to 15”
(380mm) diameter, and have recently created
a revised, single-magnet design.
For Martin Levan’s purposes, the
advantage of the Dual
Concentric driver was that you
could remove it from its
box and mount it open
without needing
separate rigging for the
high- and lowfrequency drivers, with
the two retaining their
designed relationship to
each other - and with the
point-source useful when
creating sound for listeners spread
across a wide area like a theatre. He used
the big, 15” Tannoy drivers, hidden within
scenery around the proscenium and
supplemented by bass units to make up for the
bass roll-off caused by the lack of
boxes. The concept worked; the
speakers seemed to just energise
the air and the resulting sound felt
like a natural development of the
theatre’s acoustic (just louder!)
rather than being amplified audio.
Levan repeated the setup on
subsequent shows, and other
designers have followed suit, the
Dual Concentrics appearing on
Broadway as recently as last
summer.
Tannoy:
> //tannoy.com
Dual Concentrics on Aspects of Love:
> //plasa.me/oi01y
. . . and on Oliver!:
> //plasa.me/4sz8z
Classic Gear: Tannoy Dual Concentric Drivers
Above: The drivers on
Oliver!, 1994.
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