Could you briefly summarise your amazing career of brilliant audio, off-the-schemes designer?
The earliest photograph of Edward James Jordan, (Ted, to everybody) was taken Circa 1933 and shows him sitting on his Father's knee wearing headphones and adjusting a "crystal set", (one of the earliest types of receiver).
With his mother coming from a musical family and his father a skilled amateur radio builder Ted could have been 'genetically engineered' for his vocation.
Six years before Ted's birth Rice and Kellogg had invented the moving coil loudspeaker. When he was two, Sir Edward Elgar made the historic electrical recording of his violin concerto with sixteen year old Yehudi Menuin at the EMI Abby Road studios.
During early childhood, his most treasured possessions were a wind-up gramophone and his record collection. Later, his love of music led to a brief encounter with the piano but he was quite unable to master Beethoven's Emperor Concerto even after three lessons so he learned to solder and built himself a record player.
Living in London, Ted had access to the major concert halls where his experience of live music planted the seed of dissatisfaction with recorded music that remained the driving force in his work for the rest of his life.
Brushing aside his college studies in building technology and architecture,
Ted started his career as an assistant in the radio laboratories of the GEC.
His first hi-fi experience was hearing Gilbert and Sullivan's Overture to
"The Mikado" played through the new GEC 8" metal coned loudspeakers
developed by Hugh Britten.
For the first time, he was experiencing an astonishingly close approach to live concert sound. Although somewhat "coloured" the quality convinced Ted of the full sonic potential of the cone drivers had not been fully developed.
With this in mind, Ted joined Goodmans. Industries of Wembley, where The
very progressive management gave Ted the opportunity to develop his own
ideas (with the proviso that if they worked Ted's salary would be
doubled, -- if not he would be sacked).
Ted now had the freedom of the most advanced electro-acoustic laboratories in Europe where he commenced hi seminal studies of cone behaviour at high frequencies.
He observed that the flexing of the cone played a vital and necessary role in the treble performance and that a very smooth and extended response could be achieved by controlling this flexure through specific design of the cone profile.
This work resulted the Goodmans Axiette, which was the first of the single
cone truly full range drivers. Its smooth and extended frequency response
outperformed all other contemporary drivers.
Without doubt, its sonic performance was further enhanced by the absence of crossover components. BUT, although much less coloured, they still lacked the 'life' of the GEC drivers and it was then that Ted recognised the advantages of the light metals as a cone material. (but that came later).
Ted subsequently redesigned the entire range of GIW drive units, extensively
researched new methods of loudspeaker loading and had numerous articles
published in Britain and abroad. He also developed a full range ESL which
made its debut at the same time (and much to the consternation of) QUAD.
Ted's last project for Goodmans was a miniature loudspeaker system using a two-inch full range unit, which was the basis for the small multi-media systems of today.
In 1962 Ted's, extensive knowledge and experience was brought together in his definitive text book, "LOUDSPEAKERS", which has never been equalled for it's full mathematical analysis of loudspeaker theory and first principle derivation of all loudspeaker parameters, (now often known as the 'TM' parameters).
Technology in the Marketplace
THE 1960's heralded the emergence of a relatively wealthy youth culture
which together with the advent of electronically processed rock and pop
music required a total shift of emphasis in loudspeaker design where
performance was judged by; high sound levels, "attack", "pace", "dynamics"
and similar epithets.
Beyond this, there seemed little commercial motivation for further progress. Whilst these qualities are important and may be well served by the ubiquitous '8 inch bass, 1inch tweeter in a box' concept which has hardly changed, the realistic reproduction of live vocal, instrumental and orchestral music is much more demanding. It is, in this arena, that E.J.Jordan Designs have established their world leadership.
Ted broke away from mainstream audio in 1963 and formed Jordan-Watts Ltd.
where he adapted his work on controlled cone flexure. The Jordan-Watts
single cone driver predated current metal cone drivers by 30 years.
Ted Jordan has now been the only worker in the industry to maintain a continuity of metal cone development and production over this time.
Ted's present Company originated in 1975 with the launch of the JORDAN 50mm MODULE, the original ancestor of the current JX53. This was a 2" metal foil coned unit which covered the entire frequency range above 150Hz and required only a first order crossover to be used with readily available bass units.
This product was so successful that the Company prospered on this alone for
a number of years. Many thousands of these units were sold largely by 'word
of mouth' recommendation.
Over nine hundred were used in the hi-tech Lloyds building in London and they were used as a voice reference by British Telecom for telephone quality control. This driver also provided the basic element for Ted's groundbreaking studies into the effect of "shaped wave fronts" on stereophonic imagery
In 1982 Ted's Company was restyled "E.J.JORDAN DESIGNS’" to reflect it's increasing custom design and consultancy services to the industry. It's activities now encompassed not only high-end loudspeakers for the home but also for auditoria, broadcasting, defence, medical and telecommunication applications.
Ted's association with high end German loudspeaker manufacturer ALR began in 1991 when their technical director and leading systems engineer, Karl-Heinz Fink agreed with Ted to pool technological resources. Subsequently ALR was renamed ALR Jordan.
Ted has continued an advanced CAD programme specially commissioned for to his requirements now supports work on foil cone technology, and in 1995 he introduced his legendary JORDAN JX Series of loudspeaker drive units. His work on the wide stage presentation of live orchestral sound has culminated in his further refinements of his Vertical Linear Array system, which creates his objective with unprecedented realism.
You have been investigating the possibility of single-driver full-range reproduction for decades, designing some outstanding drivers like the Goodmans Axiette and the Jordan Module. Nowadays it seems the full-range single-driver fever is infecting the World of Audio again thanks to Lowther-like 'speakers and low-powered SET amplifiers. May you please tell us your experience on full-range drivers? Pro's and con's, main drawbacks & pluses etc.
Natural sound, from a soloist to a full-scale orchestra has an immensely complex harmonic structure, the lifelike reproduction of which demands a loudspeaker capable of a very precise response to detail particularly at low levels.
Since every electronic, mechanical or acoustical component in reproduction chain will, regardless of purpose, degrade fine detail, the fewer components between the amplifier terminals and the listening room, the better.
This includes conventional "mid-kilohertz" crossovers, which, in addition, destroy the natural integrity of the harmonic structure by the abrupt severance of the harmonics from the fundamental frequencies.
These problems are avoided with the single cone moving coil driver which is
to loudspeakers as the wheel is to the car, ….Simple, effective and with no
The sonic advantages derive from the intrinsic behaviour of the cone which tends to provide a natural complement to the air load at it's surface.
Simply put, the air load properties are such that low frequency sound radiation requires a relatively large rigid cone whereas high frequencies need a progressive reduction in cone area and mass. Loudspeaker cones tend to mirror these requirements in that they are substantially rigid at low frequencies but high frequency flexing progressively reduces the effective area and mass.
Work on cone flexure pioneered by me, has refined this behaviour to achieve
an extremely close match between the cone and air load characteristics.
Formed from a light metal foil, my cones are able to respond with instant precision to the voice coil drive achieving an unparalleled standard of live sound accuracy.
Attention has also been given to the cone support. Good design requires the
cone movement to be controlled by the rear suspension, which normally
consists of a corrugated cloth device fitted behind the cone. Tests showed
the performance of this to be very unreliable at low frequencies where its
properties varied with time, temperature and signal level.
The effect on the drive unit parameters could result in errors of up to 60% in enclosure design. This was detailed in an article "The Parameter Game" by Ted Jordan, published in 'Hi-Fi News', July 1996. Our answer to this is the JORDAN Axiline suspension fitted to our bass drivers behind the magnet assembly.
"Live stage" realism can be greatly enhanced by the maintenance of low level
detail, which we have already addressed, and attention to the sound
distribution pattern throughout the listening room.
The polar response favoured by convention is quite unsatisfactory. My approach provides a directional and gently rising high frequency response with the loudspeakers placed with their axes crossing well in front of the listener. It is also strongly recommended (again, against all convention) that loudspeakers be placed as close to a wall as possible.
The simple reason for this is that wall reflections will create two further 'virtual' loudspeakers that will create severe interference and impair spatiality. (The ideal, if impractical solution is to mount the drivers in the wall).
Ultimate live stage realism is achieved by the JORDAN LINEAR ARRAY design
which includes four JORDAN JX53 drivers mounted in an in-line vertical array
for each channel.
The sound is radiated from these in the form of "cylindrical" waves, which integrate to provide a remarkably stable, three-dimensional stereo imagery. The resulting live performance, realism is unprecedented and imagery is maintained regardless of the position of the listener.
This system requires the accompaniment of a good bass system where there are a number of options available.
One of the worst audiophile's nightmares is "soundstaging". This search for a realistic "virtual" soundstage into our listening rooms seems one of the most difficult tasks nowadays. Following your vast experience, may you suggest some golden rule to get precise and large stereo image at home?
Or is it just another audiophile's craziness (as many designers say) and we should simply pay attention to dynamics and low coloration, disregarding 3D imaging?
The sound distribution or polar response of a loudspeaker drive unit is a function of its physical dimensions and bandwidth. Radiation from the cone starts to become significantly directional when one quarter of the frequency is divisible by the cone diameter.
It would seem at first logical to design loudspeaker systems to have the widest possible angle of distribution, in fact the omni-directional design would seem ideal - actually this is quite untrue. It is now generally recognised that omni-directional systems have never been popular, although the reasons have not been appreciated, and these are:
In many situations, there are considerable advantages to be gained by the
use of specifically shaped distribution patterns. This can be readily
achieved by the use of multiple arrays of identical speakers mounted closely
together. By the choice of the array shape and dimensions, the distribution
angle in any plane can be determined.
This is of great value in large halls or auditoria where the sound may be placed exactly where it is wanted with a very high degree of control over the relative level of reverberation.
A problem frequently encountered in theatres, concert halls, churches,
lecture theatres etc, is that the sound of live speech or music at the front
of the hall is inadequately heard at the back.
Not only is the direct sound level reduced but the proportion of reverberant sound is increased, the combined effects of which are to effectively remove all sound detail. Speech particularly may be rendered quite unintelligible. One approach may be to use loudspeakers distributed throughout the hall, but this alone is unsatisfactory because the sound will always appear to emanate from the nearest loudspeaker instead of the live sound source at the front.
In addition, considerable confusion of sound will result in time delays between loudspeakers and the source. A partial solution is to deliberately introduce time delays in the electrical feed to the loudspeakers, which increase appropriately towards the back. Of the hall, so that at any point in the hall the sound from the nearest speaker is in phase with that from the live source. This technique is expensive and not completely satisfactory.
A totally effective solution to this problem can be provided by the use of
two specifically designed multiple arrays correctly positioned at the front
of the auditorium.
Obviously, such arrays may have to handle very considerable power levels especially in large auditoria where the power may run to several kilowatts. In the past, such loudspeakers would need to be extremely large, heavy and unesthetic in appearance, making correct positioning difficult.
However recent developments in loudspeaker technology make it now possible to design power arrays in extremely small packages. For example, a one-kilowatt array can be housed in an enclosure of 24 litres with a frontal area of less than 0.1 sq. metres. Such an array could operate down to 100Hz.
Frequencies below this could be handled by appropriately larger bass
systems, which can be unobtrusively positioned away from the main arrays.
The use of a crossover frequency of 150Hz would ensure that the bass frequencies appear to originate from the two small arrays.
We have already indicated the significance of sound distribution to
stereophonic distribution to stereophonic performance and we now look at
this in more detail.
Consider firstly the factors, which determine how the location of a particular image is defined within the effective sound stage. Imagine two loudspeakers in the conventional stereo position reproducing a central voice.
If the listener is centrally positioned between the speakers, he will hear a central image of the voice because the loudness from each loudspeaker will be equal, and the sound will be in phase.
If the listener now moves left of centre, the apparent sound level due to
the left speaker will be increased and that from the right speaker
decreased. We will call this the proximity effect, and if the speakers have
a wide polar distribution angle (which implies a spherical wave front) the
sound level at the listener from either loudspeaker will be inversely
proportional to the square of the distance.
Also the time taken for the sound to reach the listener will be deceased from the left speaker and increased from the right speaker. This is called the precedence effect, and the time taken will be proportional to the distance.
So it seems that if the listener moves left of centre both proximity and precedence effects operate to shift the image to the left; and since with omni-directional systems the proximity effect obeys a square law, even a small shift to the left on the part of the listener will tend to move the image over to the left loudspeaker- or it will become vaguely broad And have markedly leftward bias
If now the actual voice were to move to the right the sound level would
increase from the right loudspeaker and decrease from the left; but the
voice will have to move well over to the right before the loudness of the
right loudspeaker is sufficient to overcome the proximity advantage of the
left, which in any case will still retain its precedence advantage.
At this point, our listener still patiently siting left of centre will hear the voice now as an image widely stretched between the loudspeakers, with no positive location at all.
When listening to music in this situation most of the sound will appear
clustered around the nearest loudspeaker, with wide images of indefinable
location stretching between the speakers.
Some sounds will be heard from the further loudspeaker contributing extreme "end of the line" instruments only.
In practice the situation is not usually so bad as this since most loudspeakers are not omni-directional and their proximity effect is reduced
You've been working on metal cones for decades. Today we have a plethora of metal cones (mostly aluminium and titanium) and even fancier space-age materials.
How do you see the development of materials applied to speakers construction? For example, do you think metal-matrix (Al + ceramics) could be successfully used in Audio as they are in other fields?
A number of materials could do this as but would offer possibly no advantages and may even present unnecessary production difficulties. We have fully investigated this.
It could be argued that the process of anodising introduces a ceramic component to the structure of the cone, however our cones have been developed to optimise the aluminium / Anodic coating ratio.
Speaking of crossovers, we have a vast choice of "mainstreams those who swear a 6 dB/Oct. is the only crossover worth for hi-fi applications, those who prefer no crossovers at all (sacrificing the lower end of the spectrum, for example) and finally those who swear by complicated and complex networks.
Your opinion on this "hot" topic?
The ideal in terms of detail resolution and phase integrity is of course no crossover at all. However in order to re-produce the extreme low end then a crossover is a necessary evil.
However, by adhering to the first order concept and keeping the crossover frequency as low as possible, avoids any problems in that so very critical mid-high frequency band.
Networks that are more complex may be used to achieve a theoretically ideal modelling i.e. on paper measures well but in reality can seriously denigrate the sound quality.
With the development of multi-channel, audio we will probably forced to install 5 or six loudspeakers instead of two. This, of course, adds many problems and variables, as interactions with the speakers into the room, for example. Which is your point of view on the future of Home Audio?
Is stereophonic reproduction doomed to an end?
I cannot attempt to comment on the future of home audio the chaotic trends of fashion are totally unpredictable. It is sad to note that the pursuit of technology in terms of DVD/AV/Audio does more to serve our addiction for sensory stimulus rather than the appreciation of music.
Is stereo reproduction doomed to an end? Its promise has never been fulfilled outside our own work. (see notes on sound distribution)
May you please tell us something about your current/future projects and designs?
We are naturally researching ways of improving loudspeaker but would prefer not to comment on this.
Courtesy by Ted Jordan for TNT.
Interview contact thanks to Bill Pilcher
Copyright © 2000 TNT-Audio - http://www.tnt-audio.com