Kenwood LS-1000

preliminary

Very rare loudspeakers with Sigma Drive terminals, superbly tight and stern looks and... few sales.

Kenwood at the time was navigating between success and somewhat erratic marketing, replacing one top lineup with a completely different one every other year after having dropped the unbelievable LX series which, quintuple alas, never went to production.

Nevertheless, Kenwood since 1976 was set on tightness : structurally, mechanically and electrically.
Loudspeakers-wise, this meant an emphasis on IN = OUT : what comes in must be reproduced exactly, whatever fluctuation or phase shift in the input signal or output level.

The 1978 LS-1900 was already on this but "flat" was another way to do it so the LS-1000 kept from the enormous LX 1979 loudspeaker prototype its "flat" nature... in part.


The 28cm bass driver is all but flat with its big ribs added. This system, more often used by JVC, helps reduce cone breakup and standing waves / resonances right within the cone's front cavity.
For the same reason, the protection cap is cut in its center and vented with a meshed grille.

Rigidity is also pursued in the way the woofer's frame is fixed to the enclosure : there are no screws or bolts but a sort of baionette, like on a Hasselblad camera lens !
This system must have cost a good deal but it is obvious energy transfer was largely bettered as the driver's frame is held throughout its entire circumferency and not only through four or six points.

The enclosure of the LS-1000, if looking like a strict box, hides at its back a very surprising geometry : the backboard is split into four triangles forming an inverted pyramid !
The center of this pyramid serves as bass-reflex port ; the top and bottom parts of the pyramid are of equal height which explains why the woofer is so "high" in the enclosure. Unusual, isn't it ?

In fact, only the mid and high drivers are really flat.
But the catalogs and ads sadly all remain mute about that tandem except to say that they are made of acrylic resin and carbon fiber...
They are both set within aluminium diecast frames but not like a Sony APM driver and its four pistons - we're probably closer here to flat drivers used by Technics in its SB-M1 series. Alas, no catalog shows any of this in detail.

The rest of the enclosure is almost free of damping materials (speed and thightness, again) and both the MF-0079 and HF-0110 drivers are set in their own sealed sub-enclosures.

The back board also has the filter and its four terminals : two for regular hookup and two smaller ones added for the Sigma Drive circuit.


The LS-1000 was exported outside Japan under the LS-1800 name and in the US under the added Kenwood Audio Purist badge.
Apparently, this was quite a super loudspeaker : tight, accurate, linear at all levels and able to take a lot of power. Why no sales ?



Until I can scan the four dedicated catalogs I found in Japan, you can see more detailed images at Mr Nisi's, or here or here, the latter with many real-life measurements.

Also a real-life pair of LS-1000s at hifi-do's.