The Early Years
the tinfoil cylinder of Edison
to the multi-bit
digital gizmos of today, the long road to 'audio
nirvana' is peppered with landmarks and milestones marking
quest for 'fidelity' in the reproduction of 'canned sound'.
at the Scientific American office on that fateful morning
back in 1877 thought the spoken words emerging forth from
the diminutive horn of the phonograph
device lacked any fidelity. But, for good
or for bad, the human mind is programmed with built-in avarice, and
like little Oliver
at the workhouse, keeps asking "I want some more".
And as technology slowly marched ahead, and as material science
became less of an esoteric black art, man's ingenuity, that
Divine spark of creativity, forged ever new technological
pieces to try and complete the jigsaw puzzle of fidelity.
The 'audio avenue' has been one long
road of inventions and innovations, revolutionary and
evolutionary concepts and ideas, peppered with signposts
that point to the spirited chase after the Holy
Grail of Fidelity.
The early days of the phonograph
witnessed increasing fidelity,
thanks to the larger and better horns and their 'mechanical advantage'.
Till the 1920s, the acoustic devices with their increasingly
sophisticated horns and diaphragm mechanisms ruled the
However, the foundations were being laid for
the major inventions
of the as yet unborn 'electrical era'.
Johann Philipp Reis installed an electric loudspeaker in his telephone
It was capable of reproducing pure tones, but it could also reproduce
Alexander Graham Bell patented his first electric loudspeaker (capable
reproducing intelligible speech) as part of his telephone in 1876.
In Germany a revolutionary
and much improved design
was thought up and patented by Ernst Siemens in 1877,
which was to provide much of the inspiration for
researchers on the other
side of the Atlantic
in the beginnings of the next century.
Indeed credit should go to Siemens for being the first
to perfect the design of the
dynamic or moving coil transducer, with a circular coil of wire in a
field that carried the audio signal, and supported so that it could
axially. Later in 1898 Sir Oliver Lodge, the English scientist,
second patent for an improved loudspeaker.The
All that was
reproduction of music was 'electrified'. The
second quarter of the 20'th century is
generally acknowledged as the beginning of the 'electrical
era' with the
introduction of the vacuum tube amplifier, the powered loudspeaker and
microphone. Bell Laboratories and General Electric of the US
were the key players in the field and this resulted in
a 'quantum leap' in
the 1920s Bell
Laboratories set itself the
developing an 'electrical music playback instrument'. It was the
those days for research labs to acquire models of prototypes of the
decades. Bell Labs and General Electric both had models of the 'babies'
Siemens and Lodge. E C Wente at the Bell Labs was instrumental in
'condenser' microphone and later the moving coil loudspeaker.
researchers at GE --Chester W. Rice and Edward W. Kellogg-- were
independently a similar goal. Though patents were granted to the two
independently, the invention of Rice and Kellogg took the limelight
practical system. Advanced for its day, the Rice-Kellogg dynamic
included 'modern' touches such as a rubber 'surround' around the edge
of the paper cone, a conical paper diaphragm
attached to a coil of wire that was energized by a large
(electro)magnet. They were the first to lay out many of the basic
tenets of loudspeaker design, such
as detailing the importance of the baffle in preventing the
the sound from the speaker's forward and backward motion.
Rice and Kellogg also
discussed the need for more powerful amplifiers to provide adequate
headroom required for quality reproduction.
It is a
testimony to the vision of pioneers like Siemens and Lodge
and the inventive genius of researchers like
Wente, Rice and Kellogg that the system they perfected
has lasted virtually unchanged for very nearly a century,
and right into the 'digital age', and looks like it is here to
That the electro-dynamic or the
moving coil loudspeaker had
virtually 'taken over' the world of audio
does not automatically mean that there were no other competent or
transducer designs. In fact, the much-touted 'modern' electrostatic
happens to have a lineage older than its more popular cousin, the
electrostatic speakers has been theorized since the discovery of
practical implementation was demonstrated only towards the end of the
At the Paris Electrical Exhibition of 1881, Professor Amos Dolbear
complete electrostatic telephone system. What is interesting
about this fact is that it pre-dates by some 30
years any attempts to convert electrical energy into sound by
means, thus establishing the pre-eminence of the technology.
continued to be made
during the 1920's and 1930's mainly in Germany.
Notable were the loudspeaker and headphones designed by
Eugen Reisz (famous for the 'marble block'
and the 'differential' ESL exhibited at the 1927 Berlin Radio
Exhibition by Hans
with a design topology that has remained virtually unchanged
till the present. In the 1930s, there was a British design marketed
name of 'Primustatic' that delighted radio listeners with its 'touch of
naturalsness', its clear mid and high frequencies.
side of the Atlantic,
at the Bell Labs, E C Wente had unprecedented
success with his 'condenser' microphone, essentially an electrostatic
which was easily a hundred times more sensitive than conventional
The Wente microphone and his 'light valve' system of sound-on-film went
'electrify' the movie industry. But it is unfortunate that Wente did
his expertise on electrostatics to the design of a speaker. Rather, he
collaborated with Thuras in 1926 to patent a speaker of the moving coil
that met the requirements of quality, efficiency and power handling.
to note that Rice and Kellogg, the masters of the moving coil/cone
were intrigued by the great sounding electrostatic speaker initially.
Kellogg did file a patent in 1929 for an electrostatic speaker composed
small sections able to radiate sound without magnets or cones or
(Cited later by Peter Walker of Quad as one of the sources for his
for designing an advanced ESL, the other being the work of Hans Vogt.)
only be surmised that they too had turned away from the demonstrably
fidelity of the ESL to the 'inferior' electrodynamic only because of
pitfalls and problems that were in the way of realising a commercially
successful product with current technology and materials.
the next 20
only electrostatic devices available were condenser microphones, which
a rare pefection and fidelity, with names like Neumann being synonymous
truly high fidelity. The ESL faded away from the scene since large,
diaphragms could not be fabricated with any reliability using the
available then, and their theory had not been worked out properly. The
'dangerous' high voltages required, the difficulty of matching them to
amplifiers (which even today remains a problem), their sheer size and
unreliable operation particularly in humid atmospheres, all made them
despite their superior fidelity. No wonder the rugged and compact cones
able to occupy centre stage for long.
will be the
before the ESL put in another appearance consequent on two events. The
was the publication of Prof. F. V. Hunt's seminal book
"Electroacoustics"(1954), which provided the solution to the
theoretical design of ESLs. A year later DuPont patented a new material
Mylar, which in every way was the answer to the prayers for a suitable
known British pro audio salesman and engineer, has been dreaming about
for long. In 1956 finally his design was ready and thus was launched
ESL-57. Legendary is perhaps the only word to describe this remarkable
as it reigned supreme and remained in production, virtually unchanged,
of 28 years. A tribute indeed to the genius and the vision of its
lifted the Quad-57 above even the best of the era was not its
technical specs. Rather, it lacked the many colourations and
came as a 'bonus' with virtually all the reproducers of the period. To
Quad's own blurb, it was "the closest approach to the original", and
audiphiles and critics, not to speak of music lovers in their droves
over, were only too happy to concur.
Walker was ready to introduce the world to a 'quantum jump' in concept
performance with the first major re-design of his loudspeaker--the
radically different ESL concept with the diaphragm divided up into
rings, with each ring fed by a calibrated sequential delay line, thus
the radiation pattern of a theoretical point source located about a
the panel. This meant that the ESL-63 behaved in a predictable fashion
was free from the shifting radiation patterns (with frequency) that was
bane of all conventional speakers. What made ESL-63 an unmatched
the synergy of speed and accuracy of the electrostatic flat panel, the
'un-boxy' sound of the dipole radiator, the coherence and 'continuity'
by a single full-range driver and, of course, the solid imaging and
'sound-staging' of the ideal point
source. No wonder the ESL-63 found a place even in the references of
competitors, and for long it has remained the 'standard' against which
loudspeakers were judged, electrostatic or not.
Surely the time was ripe for the ESL.
Improvements in programme material, programme sources and
better recording techniques were all 'conspiring' to show up the many
shortcomings of the 'cheap and cheerful' cones.
main hurdles to the production of an ESL had been overcome, many got
bandwaggon and today we have an array of ESL makers, each claiming to
ultimate in fidelity. But sadly the laws of Physics remain immutable
ESL, as we know it today, cannot hope to span the entire audible range.
is but a small step from the electrostatic planar to the
electrodynamic planar loudspeaker. In all
likelihood many must have toyed with the idea, though they must have
from fruition by the unavailability of powerful magnets. In the mid
20th C, all
that changed and powerful ferrite and ceramic magnets became available.
the first practical and commercially successful magnetic planar
the brainchild of Jim Winey -- the Magneplanar launched in the early
The best of the magnetic planars are often rated on a par with the ESL,
though like the ESL their physical limitations are something that
be wished away. A close relation is the ribbbon loudspeaker, which are
often used as tweeters or supertweeters.
But rarely do you find a full-range ribbon loudspeaker.
overview of loudspeaker technology cannot
overlook the 'ancient'
bending wave loudspeaker. Bending
use a diaphragm that is intentionally
with the high frequencies radiating primarily from the central area,
longer waves reach the edges of the diaphragm. The BWL has the
cover the entire audible spectrum and
have been promoted as being close to an ideal point sound
source. It is
intriguing that though the technology has existed for nearly a century,
only rare working examples.
our 'digital era', we have to tread the known
and familiar pathways, filled with
reflections and reverberations and what not, in our never ending quest
fidelity. It has been a long and tortuous route, but nonetheless a
pleasing and satisfying trip in
The 'marble block' Reisz microphone was used by the first
German radio station
broadcasting from Vox House on Potsdamer Platz in 1923, and later by
BBC. As a matter of
fact, the Reisz mic
was the brainchild of his employee Georg Neumann, who later achieved
the motive force behind the successful Neumann
 Vogt was one of the 'tri' that
sound-on-film system in
1919; the others were Josef Engl and Joseph Massolle.
Later the rights to the Tri-Ergon
system were purchased by the Fox Corporation of the U S.