ESS amt1b
Price unknown (1 unit, around 1970 s?)
Commentary
A floor-type speaker system that uses Hail drivers and passive radiators.
The amt1b uses exactly the 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.
The passive radiator is arranged to operate in series just behind the woofer to improve low-range playback.
Model Rating
| Method | 2-way, 2-speaker, passive radiator system, floor type |
| Units Used | For low band : 30 cm cone type High pass : Hail Driver Passive radiator : 30 cm cone type |
| Frequency characteristic | 35 Hz to 23 kHz ± 3 dB |
| Output sound pressure level | 90dB/W |
| Allowable input | 375W Clean Power |
| Crossover frequency | 1kHz |
| External dimensions | Width 413x Height 895x Depth 413 mm |
| Weight | 39.6kg |