I received half a dozen jpeg attachments today, from an individual who has worked for Hartley for 40+ years.."hands on" involved with the construction of these marvelous hand-built loudspeakers.

Here is an excerpt from one:

"The Voice Coil ...In our mid and full range speakers, our voice coil is actually two voice coils. They are physically isolated by a specially prepared compliance only 4 mils thick. The outer coil is made of copper and the inner of aluminum and the physical separation allows the inner aluminum coil to move independently at higher frequencies. Because the total coil is only one inch in diameter, our cones can be of maximum mass. The HARTLEY voice coil was patented in 1964 by Harold Luth, and because of its unique design, ITS THE ONLY VOICE COIL THAT DIRECTS HIGH AND LOW FREQUENCY SOUNDS TO SEPARATE CONE SECTIONS OF THE SPEAKER. "

I don't own this driver, but I do own one of their 18" subs.
This 10" full range ( 9" effective piston diameter )
is rated 20hz to 20 khz !!!
~ max peak to peak excursion - .375"
~ 25 W min, 75 W max, 150 W max peak
~ effective mass ( coil + cone ) 38 grams
~ 6 ohm
~ 6 lb (special) magnet

The Hartley drivers are also unique in that they are " magnetically suspended " ( also patented by Harold Luth ) and exhibit TRANSIENT RESPONSE times unmatched by any other loudspeaker !!!

SEEMS TO ME TO BE THE IDEAL FULL RANGE DRIVER !!!

WHAT DO YOU ALL THINK ?