SOUND BASICS

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 fine detail particularly at low levels. Since every electronic, mechanical or acoustical component in the 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 viable alternative. The reason for this is that the intrinsic behaviour of the cone tends to naturally complement that of the air load at it's surface. Simply put, for low frequency sound radiation, the air load demands a relatively large rigid cone whereas for high frequencies a progressive reduction in cone area and mass is required. 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 profiling, pioneered by JORDAN DESIGNS, has refined this behaviour to achieve an extremely close match between the cone and air load characteristics.

It should be noted that amplitude of cone flexure is very small. At low levels, and particularly at high frequencies, it may be measured in microns and lost within the thick amorphous structure of conventional cones. JORDAN cones, accurately profiled from fine gauge light metal foils, have the ability to resolve the low level detail that imparts the 'breath of life' into sound which would otherwise be just technically good. (These are not to be compared to ordinary thick metal cones which make a failed attempt to achieve total rigidity.)

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 may be very unreliable at low frequencies where its properties varied with time, temperature and signal level. This was detailed in an article 'The Parameter Game' by Ted Jordan, published in 'Hi-Fi News' July 1996 where it was shown that these effects on the drive unit parameters could result in errors of up to 60% in enclosure design. Our answer to this is the JORDAN Axiline suspension fitted to out bass drivers behind the magnet assembly.

A further issue to be addressed is the sound distribution pattern throughout the listening room. The wide random sound spread favoured by convention cannot support stable stereophonic imagery. JORDAN drivers have a slightly directional and gently rising high frequency response and should be placed with their axes crossing well in front of the listener. This approach results in a substantial improvement in image stability and reaches its full potential in our 'Linear Array' designs. Again, despite convention, there is strong argument in favour of placing the loudspeakers as close to the wall as possible. This reduces the time lag between the direct sound and the reflection from the 'virtual images' and substantially improves coherence and spatiality. (The ideal, but usually impractical, solution, is to mount the drivers in the wall where there would be no virtual image).

A unique feature of our superb range of JORDAN JX Series drive units is that they may be regarded as 'building bricks in sound' offering a range of driver combinations to create a virtually unlimited range of system designs, from small 'crossover free' nearfield monitors to the incomparable Linear Array system. (We once designed a 2.5 Kilowatt system for the a client in the Emirates.) Click on SYSTEMS for examples of basic arrangements using our drive units.