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John Wright (1939-1999)

4 June 1999

The death has been announced of John Wright, an audio-industry figure and stalwart of some 35 years and founder of TDL. This he later established as one of the few remaining British loudspeaker companies with an international pedigree still to be in private ownership at the end of the century.

John Stuart Wright was born in London on the 11th May 1939, the son of a highly academic musical family (both his parents were music teachers - his father a headmaster). Not surprisingly, young John soon developed a keen interest in music, later to be overtaken by an early enthusiasm for audio engineering which came to fruition in the 1960s when John became a joint owner of a business importing and distributing microphones and tape recorder mechanisms. A particular interest in transducers led to the design of gramophone pick-ups and record cleaning machines under the name Audio & Design. By the 1970s, having been engaged by Goldring working on cartridge and turntable technologies, John had set up business himself producing high quality loudspeakers pioneering the transmission line principle. This was achieved as a result of a joint venture with IMF Electronics Ltd and a major drive unit supplier, ELAC. The joint venture was to be named TDL.

Having helped set up TDL John sold his interest in the business in 1979 to join an academic research project in surround sound. Concurrent with this John worked variously as a free-lance audio journalist for many leading magazines and as a consultant to the National Research Development Corporation (British Technology Group). He rejoined TDL (then part of ELAC) in 1984 and in 1991 organised a management buy-out to restore TDL as an independent hi-fi operation. Under the name TDL Electronics the company concentrated on the design of affordable floor-standing loudspeakers employing a ‘reflex’ version of the transmission line principle. These, together with smaller bookshelf and dedicated home cinema loudspeakers, provided TDL with a complete range of competitive products.

Towards the end of the 1990s John Wright began to suffer ill-health (he had developed cancer) and this, combined with the financial failure of TDL’s main supplier, made it necessary for the company to be restructured with John selling his commercial interest in the business but continuing as a consultant, providing valuable technical support.

John Wright died on 1st June 1999. A qualified science teacher and a Member of the Audio Engineering Society, he will be remembered as a charming, deeply knowledgeable (but profoundly unassuming and modest) man of the ‘old-school’ of the British audio industry. Few who met him could fail to like him.

His wife and three children survive him.


History of IMF

In 2002 I received an email from John Hayes. He describes the history of IMF. Here it is :

Dear Whoever,

I read with interest your site describing the background of IMF. I am the sole survivor of the three Directors of the Company. I first met John when I was a Director of an electronics company in Amersham, Buckinghamshire. We jointly designed a record turntable made of perspex (Plexiglas). John designed the tone arm and we won some design awards. It was belt driven and servo controlled by a separate electronic control module. At that time John was interested in producing a transmission in line speaker and had made one for Irvine Freed to demonstrate a wide range Decca cartridge at the New York Hi fi show. After the show, Bud said he had taken a number of orders for this speaker and John and I got together and started to manufacture the original professional monitor. Of course, Bud, had a called it the IMF, and therefore, perhaps mistakenly we registered IMF and formed and IMF company. The Directors being myself, John Wright and David Brown who was a partner of mine already. At no time did Bud Freed have any input on the designs. We sold him speakers and he was the US Distributor until he made some cheap speakers and called them IMF. We pointed out that we had the rights to the registered name and that by making a cheap, poor quality speaker would cause damage to the reputation. He refused to back down and it ended up as a lawsuit which we won. Bud was never involved with the British IMF Company and only visited a couple of times. He never forgave us for blemishing his reputation which he had promoted in the USA as an entrepreneur and hi fi fanatic. After the lawsuit we formed our own American Company and distributed ourselves throughout the USA.

For a time we sub contracted cabinet manufacturing and bought in drive units from KEF, but decided it would be preferable to make our own drivers and cabinets. We bought a cabinet factory near Oxford and formed an alliance with Elac to make the drive units. We formed a company jointly owned by IMF and Elac (TDL). The most significant was the large base unit which had a thick tapered styrene cone with a plastic coating, this produced a rigid piston action and was extremely light without any cone break up and produced an excellent fast response at low frequencies. We were one of the first companies to use Ferro fluid in tweeters reducing ringing and giving good heat dissipation. John and I worked closely together on new designs. My idea was to produce a smaller transmission line speaker but size limited the length of the folded line, which meant the port went out of phase too early. The answer was to fit a low resonance base unit where the port would normally be. The cross over system had a separate filter for the lower base unit and maintained and in-phase response to around 18 Hz. Internal air pressure prevented the cones being over-loaded with high power low frequency pulses. The super compact was effectively a tuned port, only I considered a flat damped panel to be an advantage.

John always wanted the finest performance and was fanatical regarding quality. He spent endless hours producing demonstration tapes for the hi fi shows that we attended. His articles that appeared in many journals reflected both his dedication and knowledge.

During this period, Prof. Peter Felgett then head of Cybernetics at Reading University, developed the idea of true surround sound and Michael Gurzon developed the mathematical formulas by which a microphone with 4 capsules in a tetra-hedral array could receive sounds from all directions and encode the signals so that they could be decoded producing side to side, front to back and height information and low frequencies (omni). We formed a team, myself, John Wright, David Brown, Prof. Felgett and Michael Gurzon. I remember spending many hours in the anacoic chamber working on the surround sound microphone. BTG then known as the National Research Development Corporation paid for the patents and ultimately, the system was perfected. Our timing was bad as the collapse of Quadraphonic made people wary of Ambisonics. Furthermore, the bureaucracy of BTG made it extremely difficult to move forward.

To promote ambersonics we at IMF formed a recording company and I and a sound engineer travelled to the States and recorded at numerous venues. The records won acclaim for the best stereo without decoding and played in surround were spectacular. We recorded Dixieland, Blue Grass and Big Band. In the UK I assisted John in recording at numerous venues including much Classical, and I still have many of the tapes. Nimbus records in Monmouth transcribed our tapes to disks and using normal equipment and decoders manufactured by IMF produced the most remarkable realism. I travelled to the States and our records were played on PBS (the US public broadcast stations) and various venues had decoders and produced the surround sound off air, with generous praise from all concerned. Meanwhile, I had formed an alliance with Dolby, but the management at BTG insisted on dealing with Ray Dolby and their demands of management, if he became involved, drove him away and he went on to develop his surround systems. Sadly, Michael Gurzon died of an attack of asthma but his work was a milestone in understanding the mathematics of surround sound.

Meanwhile, IMF continued with a wider variety of speakers. We designed a speaker for surround sound with a balanced polar diagram, this is the MCR2A. this was designed to have a reasonably narrow polar diagram so that it would integrate effectively and maintained phase when used in fours for surround or in eights if height information was to be included.

Due to my personal connections at Buckingham Palace, I persuaded those with influence to get the BBC to record, with our help, the marriage of Diana and Charles at St Paul's Cathedral. The BBC after some persuasion agreed and the BBC installed surround sound microphones both inside St Paul's and outside to capture the crowds cheering. I still have the BBC Master tapes. The BBC asked BTG to pay for the cable, (everything else was free) and BTG said they wouldn't pay the ?500.00 expense. After some argument they paid. I was invited to Kensington Palace to play the tapes for the Royal's approval prior to their release. I remember we installed four studio monitors and managed to wake up the Duke and Duchess of Kent by demonstrating at what I thought was a reasonable level.

The world moved on and despite Denon, (Nipon Columbia) taking out a licence, I can say that BTG were a hindrance as, having paid for 115 patents their bureaucratic Civil Service mentality tried to exclude our help and co-operation and put on demonstrations with no technical ability, speakers wired the wrong way round etc. etc.

The world economic situation hit our cash flow and David Brown resigned and eventually went to the States to retire. He sadly died of cancer several years ago. I had worked with David Brown when he was Sales Manager and I was Works Director of Dawe Instruments a subsidiary of Lucas CAV. We came to the conclusion that we should terminate production and move in other directions.

We originally sub contracted drivers to the Elac company and subsequently formed a joint company called TDL owned by both Elac and IMF.

John decided that in co-operation with the existing TDL Company and with the support of Elac would manufacture transmission line speakers under the TDL label. Eventually a TDL company became independent and John continued but his health was failing. He also died of cancer a few years ago and the TDL name lived on for a while. But, in my opinion, without the entrepreneurial spirit and a large investment, TDL was not going to survive.

As you will no doubt see, I am disposing of much of the hi fi equipment on Ebay, with the help of one of my engineers. Obviously the history is more complicated than I have said, but I still believe that we made some of the finest speakers ever produced. I have the most fond memories of John locked in the anacoic chamber and the hours we spent listening and tweaking to produce the desired effect. On a final note I remember swapping a pair of professional monitors with Dr. Nacamichi for one of his model 1000 cassette decks and visiting Japan and spending several days with Nipon Columbia and Denon looking at their latest developments and sitting in their listening room with a pair of our monitors and a pair of their latest speakers. After some time I was asked what I thought. To be polite I said there speakers, which had been designed using laser technology, were interesting and had a good response. The President looked at me, smiled and said, "Why are you speakers so good and ours are bloody awful". Those were the days.

Bud Freed was never a Director or shareholder of IMF Electronics. IMF electronics were the only company manufacturing the transmission line speakers. The name IMF was adopted because Bud Freed had demonstrated the first prototype speakers at the New York hi fi show, and because of the publicity and the fact that he had used his name on the then unnamed speakers, we stuck with the name which was a mistake on our part. It was never his company. After our lawsuit he called his speakers Freed.

I am just about to dispose of two integrated, high quality lab designed amplifiers, with built in UHJ decoders. There are four 100 watt outputs plus an additional output for omni directional base to feed a sub woofer.

They have the usual inputs and controls with solid state switching for mono to all outputs for surround balancing, side to side and front to back balance, UHJ decode, and stereo decode with variable width to wrap-round stereo signals. They are standard rack size, anodised black front panel.


John Hayes

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