Pioneer S-933

May
1 9 7 9 may 1979
1 9 8 3 1983

Little later sister to the 1977 CS-955, launched alongwith the updated S-955 and meant to battle in the same price range as the Yamaha NS-1000M bestseller.
Same technology but simpler and smaller ingredients.


The tweeter is the same PT-R7A Beryllium ribbon leaf allowing a 120Khz frequency response ; it is described elsewhere on TVK.

The mid has the same size and also uses a Beryllium diaphragm (vapor-deposited on a copper mold) but its suspension was quite different and probably didn't call for 100% hand-mounting as the original version did.
Whereas the original 5-point circular suspension required hand-threading and assembling, the 6,5cm mid driver of the S-933 uses a pre-formed and pre-cut sandwich of copper and elastomer to make the suspension - see images #4 and #5.

The goal of this original suspension was to be able to keep perfect movement geometry even at very high output levels as well as avoiding having too much sound radiate from the edges of the diaphragm, where dispersion isn't linear and distortion higher.
This mid driver has a frequency response topping at 20Khz (!), 12Khz above the crossover frequency set in the S-933 (!!).


The bass driver shrinks from 36cm to 32cm - which is still enough to shake deep da tiled floor.
The cone itself is corrugated and is made of a special stiffened pulp ; the center cap is of aluminium and the 16cm magnetic circuit has a T-type polepiece.

The enclosure is smaller and 15kg lighter than the original CS-955 (or S-955) but retains a large bass-reflex vent like the latter, if a simple round hole rather than a tuned rectangular aperture. No plywood either here - not at 108,000¥ a pair.
Unlike its bigger siblings, the filter doesn't allow bi- or tri-amping but shows select parts and clean layout nevertheless ; it also has surprisingly large terminals for a 1979 design.

Drivers were also kept in symmetry and the overall finish is glossy ebony of the strongly red-ish kind.

I don't think this set sold as well as it probably could have... had Yamaha not made the NS-1000 some five years earlier.

Pioneer S-933, image 1 Pioneer S-933, image 2 Pioneer S-933, image 3
Pioneer S-933 specifications
Title Value
System : 3-way bass-reflex
Bass driver : 32cm cone
Mid driver : 6,5cm suspended Beryllium
High driver : PT-R7A Beryllium ribbon
Nominal impedance : 8 Ohm
Frequency response : 30Hz...120Khz
SPL : 91dB / 1W / 1m
Input power : 100W
Internal crossover : 950Hz
8Khz
Dimensions : 39 x 68 x 37,8cm
Weight : 31,5kg.
List price : 118,000¥ (1979-1983)
page online since : may 2010
page updated : may 2010
page type : LGT / KNB
page weight : 220.71 Kb / 0 b
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