Wharfedale 877, 539 manual THE 75mm 3” SOFT DOME MIDRANGE, THE 25mm 1” SOFT DOME TWEETER, General

About Your Loudspeaker 21/01/03 11:06 am Page 4

THE 75mm 3” SOFT DOME MIDRANGE

A studio monitor quality large dome midrange is used over the crucial midband frequencies, 800Hz to 3.7kHz. A feature of this driver is very low distortion over its entire working range, it is typically less than 1% at 100dB at 1 metre.

It is mounted in a custom matched fascia plate to provide partial horn loading, giving a broad angle of dispersion to its upper crossover point. The fascia plate is of die cast aluminium, it is designed to place the units as close as possible for the best integration and point source effect. Both the units are loaded by elliptical horns to reduce the diffraction effects found with symmetrical openings. The edge of the fascia itself also has the same elliptical assymetry. It has a large 75mm 3” voice coil again based on a rigid half hard aluminium former. The dome is pressure equalised by an underside baffle and chamber.

THE 25mm 1” SOFT DOME TWEETER

The highest frequencies are handled also by soft domes, these are a better choice than the metallic based domes that seem to add there own character to the treble. Again a feature of the tweeters as with the mids, is wide dispersion and very low distortion typically less than 1% at 100dB at 1 metre.

The forward unit features a high flux alnico magnet structure and is typically 93dB 1W@1M. This unit has a frequency response extending way over 20kHz to 45kHz.

The ambient effect of the highest frequencies can be enhanced by switching on the up firing tweeter, it is a complementary design to the front tweeter and forward sensitivity is not increased. It too is a 25mm soft dome but on a neodynium magnet system.

THE CROSSOVERAND WIRING

Monster Cable XP is used throughout the internal wiring. All inter-connections between wires and crossover/drivers are made by mechanical crimping. Soldering or iron parts are used within the crossover. No printed circuit boards are used. All inductors used are air cored and use large gauge wire for very low insertion loss. All capacitors used are either, low loss, low ECR polypropylene or high quality audio grade reversible electronics.

GENERAL

The reflex system uses a very large port. This has a large transfer volume and ensures low air speed within the port. Thiele – Small recommend 5-10% of the speed of sound and length approx to the diameter. The mach number for the Airedale Heritage port is M.N. 0.025. Very low. This is confirmed by the results, the Airedale Heritage port seeming virtually airless.