[esprits4s]

Hi,
  The brochure linked in the forum as well as the Stereophile review indicated that the IIA/R's had 1 front mounted 15" active driver and one top mount, slot loaded, 15" passive radiator. 
  However, my set has a 15" driver mount in the bottom of the speakers as well.  The parts list shows two active 15" drivers and the schematic shows two 15" drivers wired in parallel.
  So, was the design changed at some point to remove one of the 15" drivers or am I missing something?

-Gary

[esprits4s]

Here are pictures of the driver and documentation that I referenced above (sorry, the pics aren't the best, but this is showing the bottom of the speaker after the base was removed):













-Gary

[Stimpy]

Thanks for posting the pictures, schematic, and parts list!  That's awesome; I wish we had more of these, for posterity. 

Also, I just looked up the ST IIa/R brochure, and that may be the cause of some of the confusion.  The brochure specs state,   "Subwoofers: 2 x 15", slot-loaded, one active, one mass-loaded PR".  But, no mention of another 15" woofer.  However, a "HiFi Buyer's Review" in the same brochure, lists the ST IIa/R as having "two 15" subwoofers, one 15" and one 12" bass driver".  So, I guess the slot-loaded bottom and top 15" drivers are the subwoofer section.  The front facing 15 and 12 inch drivers are bass woofers and mid-bass drivers.  As such, I guess your speakers are normal, special, but normal!

https://www.dropbox.com/sh/ixvf72l261w5wwd/AADQPYPg5Eg5UwH7XX2K6DvWa/VMPS_Super_Tower_IIa_R_Brochure_B%26W.pdf?dl=0

[esprits4s]

Yes, good catch.  The Audio review from 1980 also mentions both 15" drivers and the 15" passive radiator. 

I'll scan the rest of the docs I received and post them when I have a chance.

[ST86]

Regarding the schematic I don't see a coil for the low pass crossover for the woofers.  Is there one in the cabinet?

Ed