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 During the mid 1960`s the development work carried out by the BBC had advanced to a stage which was beyond the capabilities of the available paper pulp cone bass units. The decision was taken to investigate the possibilities of using some form of plastic as a cone and surround material. Some two years were spent making 12 inch unit cones in a variety of shapes and from a range of plastics. The first successful unit was made from the now well known Bextrene and used in the development of the BBC studio monitor type LS5/5.
My part as a laboratory technician in the operation, was to do most of the actual work both on the plastic investigation, and the development of the LS5/5. With that experience I decided that it should be possible to make a loudspeaker from scratch in the home environment. With the aid of our electric fire, a compressor working in reverse and an old iron bedstead, the first vacuum former was built. Bins full of malformed cones were produced before any measure of success was achieved and the first 8 inch unit was produced. This turned out to be the first commercial 8 inch bextrene driver and still arguably one of the best.
The first pair of BC1`s was constructed using these units and Celestion HF1300 tweeters. The cabinets were smaller than the now famous commercial product and initial listening tests indicated that the performance could be improved by an increase in size. At this point it was all being done for fun! The second pair of BC1`s was made for a friend who took them to Merrow Sound of Guildford, Surrey. The third pair was sold to Merrow Sound and Spendor was on the way to a small niche in the audio world. 
Now some difficulties were beginning to arise as under the terms of my contract with the BBC, the design had to be offered to them. Fortunately the "pop" era had just started and the main request was for more power, so the BC1 was turned down. Around about this time there was a special requirement within the BBC for one pair of speakers about the size of the BC1`s. Being a kind soul I suggested that my design could be used, so I was given the task of producing an official version of the BC1, later designated the LS3/6.
This design used an 8 inch unit made by the Research Department, the Celestion HF1300 and a redesigned crossover. The main change in the crossover was the addition of a large multi-tap auto transformer to allow adjustment of levels between the two units, normal BBC practice at that time.
Some months later BC1`s were fitted with an amplifier mounted in the back panel and the 4001G super tweeter added. This addition was for purchase tax reasons, but it did have two extra gains. Firstly it improved the overall dispersion characteristics, secondly, from the broadcasting angle, it made the detection of any 625 line breakthrough more easily detected.
Now the LS3/6 was offered to a number of commercial companies and eventually taken by Rogers, then under the control of Jim Rogers.
Ironically, as Spendor was now a commercial company, it was agreed that a royalty should be paid to the BBC for each BC1 produced. This was in recognition of the work I had done on the loudspeaker whilst still employed by the BBC.
To perhaps prove the order of development of the two systems, it is of note that out of over two thousand BC1`s supplied to the professional market to date, there are over six hundred in operation with the BBC and as far as I know very few, if any, LS3/6 loudspeakers....... |
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