Very rare and beautifully designed superlative loudspeaker which looks like a mid-end thing but isn't : it weighs 52kg (!) and uses ultra materials, diecast drivers' frames and shows very little distortion.
The EAS-30PL100S bass is a 30cm cone with hand-made low-loss three-layer diaphragm, 10cm voice coil, large magnetic pole and twin-suspension system.
The EAS-18KM100S midrange is again a low-loss three-layer diaphragm with laminated steel core, double damper symmetrical structure.
The EAS-12KH100S tweeter is a 20µ titanium dome with Fe / Co 19,000G high saturation flux density and 30Khz response.
The network is a very low-distortion (0,1% at 100W output) with super parts such as E-core silicon and MP caps ; it can also be bypassed for three-way active amping.
The enclosure uses 3,6cm thickness walls done in three layers (0,9cm + 1,8cm particle board and 0,9cm plywood) and is partly separated in two.
The SB-1000 truly is an exxcellent loudspeaker using techniques well in advance of its 1972/1973 inception.
Until I can get my japanese catalogs properly translated, you can read about the SB-1000 in detail here.