Field Coil Magnet Drivers

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The field coil Lowther is a brand new design. It uses current through a large copper coil to create the magnetic field rather than the standard permanent magnet.

The design has been built, and revised using both finite element magnetic modeling and listening evaluations. A small number were built and distributed to experienced listeners to develop appropriate feedback. We are confident of its sonic superiority.

The picture on the right shows some of the original units. New units have a satin nickel finish.

It is difficult to put into words the difference that this design makes in the sound. The easiest description is relaxed. There is an absence of grain, making them very easy to listen to over long periods of time. Subtle information appears, and it always sounds consistent as part of the music and ambience. There is no artificial bite or edge that some speakers have.

The nature of the magnet allows a certain amount of tuning to be done to suit your taste. At nine volts the sound is very relaxed, with a slight distance to the soundstage. At twelve volts they have a fairly forward sound. When powered at ten to eleven volts they have an extremely balanced sound, with both the leading edge of transients and harmonic development of the notes being portrayed in very natural way. Current under these conditions varies between 2 and 3 amps. A good, clean power supply is required.

The magnet is large, about 31 lbs., and requires a separate support for the magnet. The cone is a standard Lowther cone, using either copper or silver for the voice coil. It can be provided with either an 8 or 15 ohm impedance.

Standard is the 15 ohm copper voice, which provides the best balanced sound, although slightly laid back. If you prefer a faster, more forward sound, specify that you want silver voice coils.

Cost:



Price is $6,000 per pair.

These are shipped in a wooden crate, with a shipping weight of 100 lbs. Shipping is additional, and will be about $100 in the CONUS depending on where you are located.

The cost includes your choice of voice coil material, and either 5 or 8" cones.

Sales tax will be added for shipments in Illinois.

Basic Specifications:
Weight: Approximately 26 lbs. per driver
Power Consumption: Normally eleven volts and 2.2 amps
Efficiency: Normally 99 dB/watt
Qts: Varies from .25 at eight volts to .21 at fourteen volts
Fs: 49 Hz with 15 ohm, copper coil.

Because you can vary the power input into the field coil, you can vary from these specifications. This is the recommended operating point based upon our taste. You should feel free to experiment.

The power supply is not included in the price. We recommend a supply capable of supplying at least 20 volts and 3 amps per driver. We have found that the Lambda and HP regulated power supplies often available on E-Bay to be excellent. Our experience with the cheap Chinese power supplies has been very unpleasant.

Because these have 25 watts of power into them, they do create a fair amount of heat. We recommend use with some ventilation (i.e. in open air), not in a closed box.

Note: Lowther Loudspeakers Systems in the UK has not participated in this design, except that they have produced the cone and basket assemblies. They have permitted use of the Lowther name. The design has been done by Dave Slagle (of Intact Audio), Jeffrey Jackson (of Experience Music), and Jon Ver Halen of Lowther America.