Sansui 1000
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Allegedly,
it was produced for only a year. The predecessor of the
Sansui 1000 was highly collectible SM-80 model. The
electronic 1000 was a copy of the SM-80, but the tuner in
the 1000 is a product that works only in the MPX stereo
system without the possibility of "stereo multicast" like
the SM-80. "The thousand" set new directions when it comes
to the construction of SANSUI receivers, from this model
the stereo system was only MPX. It shared with the early
500 model and TU-70 tuner a relay used to turn on a 6.3V
bulb as an indicator of a stereo signal. The 6.3V bulb was
complemented by a huge orange plastic disc on the front,
which, after receiving the information about the MPX
signal, glowed not very discreetly, or even
demonstratively. It was the beginning of FM stereo and
this probably explains the "demonstrative" operation of
the stereo indicator. This was probably the intention of
the designers. Electronically the said receiver shared
radio path with 500 model. Both models had FM head based
on one ECC85 duotriode. Cosmetically, the 1000 model was
also very similar to the Sansui 500. A simple, almost
ascetic front panel made of 3 mm thick aluminum sheet, and
a narrow glass scale at the top. However, the switches
were different - the push-button type (with 500 sliding
ones) and in a different place. They were located under
the glass scale and above the potentiometers and switches.
The tuning indicator was also different. In 1000, the
pointer indicator was introduced for the first time in
Sansui. It is small and it gave the impression that it
comes from a completely different device, but it is always
something new. When it comes to the design of the power amplifier, the electronics of the 1000 is also unique. Sansui used the 25E5 / PL36 power pentodes in several of their products for some time. These tubes, designed for the needs of black-and-white TV sets, turned out to be useful for constructing audio amplifiers but only working in Push & Pull circuits (apart from Sansui, only Philips used PL36 and mainly for P&P OTL amplifiers). 25E5 / PL36 were (and still are) widely available, cheap and did not require high supply voltages. They could provide a lot of power in the Push & Pull configuration, which was very important with budget designs, such as Japanese receivers. Sansui 1000 used today is very cheap to operate, because despite the increase in prices, PL 36 lamps are treated as the so-called "junk lamps" and you can buy them cheaply. According to The manufacturer had a power in the sine of 2 x 33 W. This is confirmed by tests. On a load of 8 ohms the amplifier gave power in a sine of 30W with a frequency response of 45Hz-25kHz. At the test the power tubes were NOS RFT made PL36. The driver tubes were the Japanese 6AN8 double tubes, and the preamplifier featured the 12AX7 or ECC83. Like most Sansui products, the correction preamp was designed as a small module based on germanium transistors. Nowadays, it is difficult to find a copy of 1000 in good cosmetic condition. Thanks to the power tubes used, they could work for years without any repairs. And so it was. In the end, however, they became technologically obsolete and were replaced by transistor devices. 
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