Sony SS-8150

Unseen, and almost un-reviewed in the press and most of the time badly photographed - not the best way to sell anything, let alone a tall, heavy and terribly expensive loudspeaker.

The SS-8150 cost 1300£ a pair in 1976, 2000$ in 1975 - as comparison points, a TA-5650 cost 230£ and a TA-8650 550£ !

The SS-8150 is the top evolution of the 1970 Ultra Linear Magnetic (ULM) lineup and the SS-7600 flagship (ULM-6 in Japan, march 1971). You could call it an ULM II : Sony in launched the ULM-66 -a revised ULM-6- in october 1972.

Despite today's recognized qualities of these beasts, it is only with the next set of lineups that Sony did become visible at last on the loudspeaker segment : 20,000 pairs of SS-G7 sold !
Even if the technology evolution is quite coherent, the SS-8150 really is more of an Invisibilia item.


The drivers refined the ULM structure by adding a silicon alloy ring around the polepiece to lower distortion caused by the magnetic circuit. This system is used for the other two drivers as well but the silicon alloy is replaced by annealed pure iron and permentur (?) for the mid and high, respectively.

These material are "low-loss hysteresis" and provide better linearity. Also added to the original ULM design is the design of the voice coil which is "mounted in such a way that the cones are dynamically balanced"...

Also, carbon : the bass driver uses carbon-fiber (CARBOCON by Sony), something re-used for most of Sony's 1976-1980 SS-G lineups ; the mid and high drivers are (hand-) coated with carbon.
Also diecast frames for all three drivers, braced beech-ply cabinet, 3-way wiring terminals (a tradition at Sony since 1965) and multi-magnet assembly for the woofer (see the USER images).
Also 55kg apiece !


Bar the winter 1973 pre-production unit, two versions of the 8150 were seen :
The last 1974 pre-production samples had the same variable port to navigate between bass-reflex and infinite baffle (acoustic suspension) as in the SS-7600. That version has a smaller top plate with a two-sided cover & scripting which says :
"This side up : CLOSED" and
"This side up : OPENED".

The production version is bass-reflex only, and has a much taller metal plate surrounding the port ; it is this version which is most of the time shown in the catalogs - although the description often is that of the original variable port !

Note that the v1 level knobs allow only level "decrease", while the 8150 v2 has its recommended positions set lower, thus allowing for a minimum of increase as well.


And... there are two versions of the 8150's woofer :
Either the coated black (probably an early Carbocon carbon treatment) or a more smooth and clear pulp, same shape but sans coating.

Sony also wandered around cabinet colour and finish (the 8150 originally was grey on every side) but finally settled on semi-matte black for the front and light grey for the top and sides - very effective and quite trendy... much beyond 1974.

For real or available for sale, I have never ever seen a pair of SS-8150.