ESS amt-bookshelf
Price unknown (1 unit, around 1970 s?)
Commentary
A bookshelf speaker system with a Hail driver.
The amt-bookshelf uses the exact same units and network as the amt-monitor, with a Hail driver in the high range and a 30 cm cone woofer and 30 cm passive radiators in the low range.
The Hail driver has a structure in which Teflon accordion pleats are placed in a strong magnetic field and elements (conductive bands) are embedded in the sides of each of the pleats.
When a signal is applied to this element, an electric current flows and the movement of the folds compresses air and emits sound into space.
Because the voice coil radiates sound directly into space by this operation, excellent damping characteristics and low distortion factor are achieved.
The 30 cm woofer cone used in the low range uses a polystyrene compound called bexstrene, which is different from pulp and was developed by BBC engineers.
Also, the 30 cm passive radiator is mounted on the rear side.
A network of 18dB/oct. is used for the crossover between the Hail driver and the woofer, and the mid and high sound above the crossover point of 1 kHz can be continuously changed from + 3 dB to ∞.
Model Rating
Method | 2-way, 2-speaker, passive radiator system ・ Bookshelf type |
Units Used | For low band : 30 cm cone type High pass : Hail Driver Passive radiator : 30 cm cone type |
Frequency characteristic | 40 Hz to 23 kHz ± 3 dB |
Output sound pressure level | 90dB/W |
Allowable input | 375W Clean Power |
Crossover frequency | 1kHz |
External dimensions | Width 356x Height 610x Depth 356 mm |
Weight | 29.5kg |