IMF people

Irving M. (Bud) Fried (1920 - 2005)

Letter from Irving M. (Bud) Fried

Another Letter to John Atkinson

I believe that speakers should preserve the integrity of the signal waveform and the Audio Perfectionist Journal has presented a great deal of information about the importance of time domain performance in loudspeakers. I’m not the only one who appreciates time- and phase-accurate speakers but I have been virtually the only advocate to speak out in print in recent years. There’s a reason for that.

It is difficult and costly to design and manufacture a time- and phase-accurate speaker system. Few of today’s high-end loudspeakers are time- and phase-accurate designs. The audio magazines need to appeal to a broad spectrum of advertisers including many who make speaker systems which are time incoherent. The magazines, and the reviewers who write for them, have ignored or downplayed the issue of time- and phase-accuracy in order to maximize advertising revenue. I am not alone in recognizing this situation.

Legendary speaker designer Irving M. “Bud” Fried wrote a letter about this subject to John Atkinson, editor of Stereophile magazine, in response to a comment that John made in one of his product reviews. Stereophile chose not to publish Fried’s letter but I received a copy. The following is an edited version for your information.

July 20, 2002

Dear Mr. Atkinson,

This communication is offered for the sake of objectivity and “truth” (a commodity not in high regard these last few weeks, at least in the world of commerce).

In your August 2002 issue, page 63, you wrote “the use of a high order crossover means that the MBL 111B is not time coherent (not that that really matters).” I think it really does matter and I’ll provide some evidence.

Within the last two years, in what I believe was the December 2000 issue of the English magazine “HI FI NEWS,” an article appeared, written, I believe, by Keith Howard, which detailed the following:

Using a B&W Nautilus Loudspeaker, which has sharp filters and thus is not time coherent, a tape was specially prepared of several kinds of music. This tape was digitally time corrected, so that the resulting output from the B&W speakers, was a time coherent signal.

An expert listening panel compared the output of the speaker from the digitally time corrected tape to the output of the speaker from the uncorrected tapes.

The entire listening panel voted unanimously for the superior realism and accuracy of the time corrected output! The article concluded that this should put to rest for all time the misconception that time accuracy is not important for high quality reproduction, contrary to the belief that your quotation expresses!

Michael Gerzon, in lab work for B&W some ten years before, arrived at the same conclusion. You may remember that he is the creator of “Ambisonics”—mentioned in various writings of yours truly.

Yet the new super speakers that turn up in the marketplace are overwhelmingly non-time coherent! Perhaps this really is due entirely to “commercial considerations,” as I was once told by my dear friend Raymond Cooke, founder and Managing Director of the esteemed KEF brand, when I questioned him on why KEF speakers were not time coherent.

I interpreted Mr. Cooke’s comment to mean that “it’s too expensive to make KEF speakers time coherent.” And so, with his help, I proceeded to make my own brands time coherent!

I have demonstrated the same condition of “time coherence” for many years—and written extensively about it. Perhaps it is time for your readers to hear that time coherence has its proponents—even though it is not much in evidence in today’s “super speakers.” In fact, the more time coherent loudspeaker condition is always preferred by those who value ”live” sound quality over “commercial considerations.”

I am always available at the stated address—if readers want the other side of the coin.

Sincerely,

Irving M. (Bud) Fried

300 E. Lancaster Ave.

Wynnewood, PA 19096

Ph/Fax 610 896 9913

Articles written by Bud

• Fried on Serie Networks

Letter from John Hayes

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.

Signed

John Hayes

John Wright (1939 - 1999)

British Audio (06/99)

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.

British Audio Journal (07/99)

John Wright 1939-1999

Paul Messenger remembers an inventive, resourceful gentleman who had more influence of the British hi-fi industry than many people realised.

John Wright was one of the more important figures on the post-war, British, specialist hi-fi scene. A gentleman through and through, he maintained a relatively low profile in recent years, so it’s all too easy to underestimate the contributions he has made to British hi-fi since the mid-1960s.

In a very real sense John was a ‘bridge’ between the first generation hi-fi companies founded in or before the 1950s, and the new wave that came into being during the 1970s. One of his strengths was an ability to combine the solid engineering traditions of the past with a more open-minded appreciation of the subjectivist approach.

The recent TDL Electronics chapter was just the final phase of a long career, in which John distinguished himself not only as a loudspeaker engineer of some repute, but also took on the roles of inventor, writer, reviewer and businessman - all with considerable success.

Both his parents were music teachers, and John himself was an accomplished pianist and organist, but he developed a parallel passion for the gramophone and the challenge of reproducing recorded music to the highest possible standards. While he started out as a teacher, his wide ranging part-time hi-fi activities gradually took over.

During the 1960s he was involved with transducers at the front end of the hi-fi chain. His Audio & Design operation developed a well regarded pickup arm with mercury contacts to avoid lead-out wire torque, as well as the original vacuum record cleaning machine that is still made today under the Keith Monks brand.

The real business breakthrough, however, came around 1970, and at the other end of the hi-fi chain, when John’s large transmission line loudspeaker designs first appeared. Made by TDL with ELAC drivers, and marketed under the IMF Electronics brand, these monitors took advantage of the availability of high power transistor amplifiers to set a new ‘high-end’ benchmark, which helped raise the status and profile of British hi-fi speakers around the world.

Although John will be best remembered for his transmission line loudspeakers, his personal enthusiasm for the whole hi-fi thing led to involvement across a much broader stage. He wrote seminal articles and reviews on loudspeakers for Hi-Fi News and Hi-Fi Sound magazines, reviewed classical music releases for Hi-Fi Answers, and covered phono cartridges and arms for The Gramophone.

In 1980 he left IMF to join the research programme that developed the Ambisonics surround sound system, alongside academics such as Michael Gerzon and Peter Fellgett. Although the consumer world wasn’t ready for yet another surround sound format, the Ambisonics principles and techniques of soundfield encoding are still highly regarded by the professional sector today.

John subsequently returned to the ELAC/TDL operation and, when Harman purchased ELAC in 1989, he organised a management buyout of the TDL brand. TDL Electronics stopped supplying drivers and systems to other manufcturers, and John introduced the Studio line, which updated the transmission line tradition with newly developed metal diaphragm drivers. He then produced the highly successful and more affordable RTL (Reflex Transmission Line) series, which cleverly anticipated the mid-1990s trend towards budget price floorstanders.

That anticipation was typical of John. Even though he viewed modern marketing methods with a certain detached cynicism, one had to admire his ability to keep one jump ahead. I would sometimes ask him a deliberately provocative question and usually received an even more challenging reply, invariably delivered with a twinkle in the eye.

Above all, I'll remember his open-mindedness and readiness-at least-to consider new ideas. Mention some tweak and the chances were he’d already tried it for himself - and he never dismissed even unlikely suggestions out of hand. One of his final acts was to sell TDL to the very experienced Gordon Provan, in February this year, to ensure the continuity of the brand, the company, and its workforce.

Some articles he wrote :

• A monitoring approach to loudspeaker design : Design Criteria and Performance Parameters-Description of recent Anglo American Research; part I, Hi-Fi News, July 1970.

  • A monitoring approach to loudspeaker design, part II, Hi-Fi News, August 1970.

Ron Bliss

Former;

President; IMF Electronics Inc., USA

Executive Director; IMF Electronics LTD., U.K.

Clive Gibson

Worked at IMF.