Is Jordan-Watts “the best loudspeaker”?

 

WHY JORDAN-WATTS LOUDSPEAKERS REPRODUCE SOUNDS SO NATURALLY AND TIRELESSLY

The Jordan-Ways loudspeaker is probably the most fundamentally correct sound reproducing device designed to date and it owes much of its remarkable performace to its basic simplicity. It began with a detailed study of the current state of the art in sound recording and reproduction, what new developments had taken place, what new materials were now available, and what were the requirements necessary for absolute accuracy in converting electrical energy into sound, regardless of cost, size, method, or "the way it has always been done".

The study showed that origins still strongly influenced design, the first "loudspeaker" being a small megaphone attached ot the earpiece fo a telephone receiver to form an elementary pressure unit. Flat diaphragms transmuted to cones and electro-magnetic development passed through the stages of moving iron, energised magnets, moving coils, permanent magnets, and as amplifier powers increased so did the size of loudspeaker cones, thus creating intermodulation distortion problems. This distortion si usually reduced by using two or more sizes of loudspeaker in each enclosure, coupled by crossover networks, so that each unit reproduces a limited band of frequencies. Different loudspeakers however, create different qualities fo sound and with the additional effect of crossover roughness, there remains ag a p between results and perfection. Furthermore the reactive element of crossovers adversely affects performance of some transistorised amplifiers.

Correct diaphragm design and size are of paramount importance in a loudspeaker. The *ideal piston* (an imaginary device having infinite rigidity and no mass) had often been quoteda s the ultimate in diaphragms design, but in practice such properties were unsuitable for wide range sound propagation.

These ideals are widely believed to be essential for good transient response and the avoidance of cone "break-up", but theoretically this is not so. Consider thin glass and lead foil as diaphragm materials. The rigid glass diaphragm on being struck would continue to ring for some seconds, an effect which in loudspeaker terms would be very poor transient response and serious cone break-up. The lead diaphragm would produce no more than the sound of the impact, showing on hangover, a very desirable reaction for a loudspeaker cone. yet lead is far softer and denser than glass. There is no inherent advantage in making a cone merely light or rigid unless these properties are related to many more

complex factors in the design.

To achieve a smooth and extended high frequency response and this is the difficult region--the effective area of the diaphragm must decrease with elevating frequency in accordance with a mathematical law, and to avoid intermodulation distortion the diaphragm diameter should not exceed about four inches. (10 cms.) These characteristics, so different from the "Ideal piston" can only occur in a diaphragm having mass and flexibility and driven at one point on its surface. They exist only in a SINGLE cone loudspeaker, which is why this type has remained supreme for fifty years.

Jordan-Watts had first to perfect a diaphragm that behaved in accordance with that law and had then to create conditions necessary for it to generate distortion-free sound radiation at an acceptable power level and efficiency. Because the optimum diameter for the diaphragm is only 4", a b o u t one third of the conventional size for high fidelity loudspeakers, Jordan-Watts designed a radically new cantilever metal suspension system to permit the large movement necessary to achieve radiated power at low frequenciesand to apply some axial restoring force to the voice coil. Every minute detail has received the same careful thought, using new ideas and new materials to create a loudspeaker of faultless performance which sets a newstandard of clarity and definition in sound reproduction. Here are some of the Jordan-Watts advanced design features:

.1 Acoustically correct size and profileof non-rigid metal diaphragm.

Proper mechanical termination at diaphragm edge and centre to prevent unwanted resonances and break-up. An ingenious flexible collar decouples the mass of the suspension system from the coil at high frequencies thus extending the level response and aiding the excellent mid-range polar radiation

.3 Triple copper alloy t a n g e n t i a l c o i l s u s p e n s i o n s y s t e m a l l o w s l a r g e e x c u r s i o n s without distortion. Unaffected by climate and does not sag with ageing as is unavoidable in

corrugated cloth discs. The suspension provides the electrical circuit to the coil.

4. its lightweight coil remains completely immersed in the deep magnet gap, even at maximum amplitude, to ensure superb transient response,Coil heat is dissipated through an aluminium former. Metal and plastic construction, unaffected by climate or humidity.

5. Massive, rigid, an inert chassis and magnet system improves efficiency of moving parts and provides a rear radiation area four times that of the diaphragm and a magnet area greater than that of the diaphragm.

6. Each module is acoustically damped to maintain linear low frequency response an advantage over electromagnetic damping because it applies equally over the entire diephragm surface instead of only the centre. This also maintains the correct damping factor where two or more modules are mounted in the same enciosure.

7. The small diaphragm area enables correspondingly small enclosures to provide superb bass performance.

8. Standing wave problems are negligible because (a) with small enclosures the relevant frequencies are high, (b) the metal diaphragm is three times less transparent acoustically than is paper (c) the open area of the front baffle is small (d) the module itself is acoustically damped.