The Sm 1000 is the very last unit fully designed in the USA, by Michael Custer, who previously also designed the Sc-7 and Sm-7.
The Sm 1000 was, however, built in Japan and the last of the "A-Line", when Philips was just about to buy 43% of Marantz from Superscope.
The Sm 1000 therefore represents the real ending of (what was left of-) the USA Marantz.
The first and second stages of the Sm 1000 are push-pull differential amps with dual transistors ; both stages are coupled with an emitter-follower buffer amp.
The final stage ouputs 2x 400W (8 Ohm) with 36 bipolar output devices (NEC 2SD555 / 2SB600, 200W each) driven by 12 drivers parallel-connected and "organized in Super Linear 3-stage Darlington construction".
There's a dual supply rail to cater for momentary high-output needs where "a voltage which is higher than that fed to the final stage is fed to the main voltage amplification stage.".
Also inside this 43kg monster are glass-epoxy PCBs, oversized logarithmic compression meters, two "cut-core" 800VA transformers, four 20.500µF / 125V caps and the Tunnel Heat Dissipator and its low-noise fan. The main capacitor array is hooked to a big, thick and fat copper plate.
The rest of the circuit are all low-TIM and all-DC - we're in 1979/80 :)
This cooling system was developped by NASA - or so the liiterature says : Sony said the same thing for the Heat-Pipe cooling system since 1977... which Marantz used for some of the smaller ESOTECs like the Sm-6.
Anyway - this tunnel / fins /fan system allows for a maximum of 8° temperature variation and was inaugurated (at Marantz) with the Model 500 and its many siblings like the Model 510M bestseller.
Beginning to appear, then, are XLR balanced inputs... which aren't balanced : pins 1 and 2 are (-) and pin 3 is (+). No grounding here.
The unbalanced inputs (those which do not pretend to be balanced that is) are doubled : one DC set and one which ads a cap for AC coupling.
Protection is limited on the Sm 1000 : either when a loud input noise, when DC...2,5Hz is received by the input stages or when ± 3V [?] lands at the speaker terminals. DC drift isn't dealt with because "little DC drift can be measured".
- read the TECH section of this page for the rest of the circuit description.
The Sm 1000 (and perhaps the entire ESOTEC lineup ?) was designed by Michael D. Custer, as signed with grandeur on a few early japanese Esotec ads.
Like its later Sc 1000 preamplifier companion or the Citation XX for harman/kardon, the Sm 1000 is, however, part of those components which had the misfortune of arriving in the midst of corporate changes and eras abruptly ending.
This may explain the somewhat erratic distribution and poor sales of the entire super-top end of what was still, then, known as the ESOTEC Series : Tt 1000, Sm 1000 and, later on, Sc 1000 and Mc 1000.
Although clearly Marantz Japan designs, the same happened to the Sc-11, Sm-11 and the two Sm 1000 variants : Sm 700 and Sm 800.
The transition between Superscope ownership and SRC production to the Philips ownership and Marantz Japan (aka SRC) gradually gaining in design independence must have made for quite few headaches in marketing, manufacturing and distribution !
The Sm 1000 was phased out in favor of the Sm 700, the new(er) companion of the (newer) Sc 1000, during the spring of 1982.
The latter two made it as Stereo Sound Best Product while the Sm 1000 never did - troubled times for Marantz.
I have more about the Sm 1000 waiting in Japan and in Paris waiting to be scanned : ads, nudies, response graphs and beautiful Marantz SG beauty shots - stay tuned !