The S2 was developed for high quality sound reproduction in cinemas. Throughout the design special care was taken to ensure maximum high frequency response which necessitated machining within very fine limits and particular care in assembly and testing.
The Alnico magnet takes the form of a tubular centre pole resulting in a minimum of external field and low losses.
The lightweight Duralumin diaphragm is fitted with a large voice coil so that maximum displacement is small, enabling the depth of the magnet gap to be restricted, thus concentrating the field and ensuring the coil is operating in a constant flux throughout its movement.
A special acoustic transformer is fitted between the diaphragm, which is at the rear of the unit, and the throat, to preserve the correct phase relationship between sound waves generated at different points of the diaphragm and avoid high frequency cancellation.
The S2 was originally designed for use with the 220 horns and when used thus the correct exponential expansion from all point of the diaphragm to the mouth of the horn are retained.
Later literature also recommends the CN481 and RH330 multi cells as well as the CN157 dispersive horn
Original Brochures here
Brochure and images available here: Stephane3000
-10 watt power handling (later brochures claim 100w)
-Frequency response 200-14,000 (some brochures claim 20,000Hz)
-Recommended crossover 550 filter (12 dB below 550)-Total useful flux 150,000 lines
-Flux Density 16,000 gauss
-Voice coil diameter 3 inches
-Effective area of diaphragm 7 square inch
-Diameter of unit 5 inches
-Overall depth 5.5 inches
-Weight 6.1 kg (13 ¾ lbs)
-Throat diameter 1.5 inches
-Thread S (2.620 inches x 16 T.P.I)
-Dimensions 127 x 135 mm
-Chrome plated to resist corrosion and supplied in a transit case.