Field Coil Drivers? Is old new again?

Aurel Bryan Mega FCM speakers in Jakarta last year

As a few of you may know I've been the Australian contact point for the brilliant wide range drivers from Indonesia, hand made under the name Aurel Bryan. The realism, energy and serious impact they can provide for a vast array of genres is really quite something!

What many people don't know is that they have a range of field coil drivers in the 5, 6 and 8 inch sizes. The difference between a field coil driver and conventional is that the field coil does not use a permanent magnet at the rear, rather employing a carefully designed electromagnet that requires an electrical charge to be magnetised. Changes to the voltage of the electricity supplied can change the sound characteristics of the driver- field coils are typically described as everything you'd expect from a top quality permanent magnet driver, turned up to 11. More detail, richness, saturation, impact and enjoyment. I think that last adjective is possibly the most important, certainly in my books.

Field coils were the first type of dynamic transducer developed, as the technology to make sufficiently strong permanent magnets had yet to come about. Over time permanent magnets became smaller, stronger and (probably most importantly form a commercial standpoint) cheaper, and thus became the default standard while the field coil fell (more or less) into disuse.

Now THAT is a magnet structure!

In addition to individual drivers, Aurel Bryan make a range of complete speakers based on their drivers, with a quasi-transmission line design and high quality veneered ply cabinets. They are called the Pico (4" driver), Nano (5" driver), Micro (6") and Mega (8"). All are available with Ferrite or upgrade to neodymium magnets, and the 5, 6 and 8" can be specced with a field coil drive unit and accompanying power supply.

A close up view. The AB speakers come with either this style of cabinet or a classic "square edged" design

Field coil drivers are far from cheap, however, in this realm, the range from Aurel Bryan could be regarded as something of a bargain as a pair of the 8" drivers come at the relatively modest cost of 2950AUD. I'm hoping to have a pair of the Micro FCM speakers available to audition in Australia very soon!