sansui
electric co.
SM-320M |
250 |
500 |
500A |
1000 |
1000A |
Initially, SANSUI receivers worked in the multicast system, for which you could buy an external MPX decoder. An interesting design was the SM-30 with 6BQ5 / EL84 end tubes - the last SANSUI model, the so-called full lamp. It was equipped with a power supply with two rectifying tubes 5AR4 / GZ34 and 6CA4 / EZ81 and a correction preamplifier based on tubes. At the same time, SANSUI was producing the SM-80 receiver. This model was also unique, the manufacturer used unique "TV" 25E5 / PL36 power tubes working in the Push & Pull configuration. The declared maximum musical power was 2 x 40 W, and with a distortion of less than 1%, 33 W per channel. The rest of the solutions set the design standards for SANSUI tubes for the next decade - a transistor preamplifier and a power supply based on silicon diodes. In the low power segment, ECL82 lamps were used to produce the SM-32xx series models, which could be received in the "multicast" system and at the same time the MPX stereo was equipped with a stereo decoder. The successor to the SM-80 was the model 1000, which set a new design for SANSUI receivers in the 1960s. A simple aluminum front panel with symmetrically arranged knobs and switches. The SANSUI 1000 was electronically a copy of the SM-80, but the separate AM channel was replaced by a very good MPX decoder, used in later products. A characteristic element of this decoder was a relay that turns on a 6.3V bulb as an indicator of a stereo signal. Large shields of output transformers have also been replaced. Compared to the SM-80, the chassis uses thinner plate. The segment of small receivers was filled with the 500 models with the possibility of "multicast" operation, because they left the separate AM channel in them, while using a decoder such as in the 1000 model. The manufacturer stated that the SM-32xx (and 500) models had a maximum power of 2 x 13 W. After these models, the next generation arrived. The previous models on 6BM8 / ECL82 tubes were replaced by the model 250 (with MPX decoder) and 220 (without MPX decoder) with lower power. An interesting fact is that it has a double "magic eye" used in "simulcast" receivers, but one of the sections is an indicator of the MPX stereo signal. This model shared a corrective preamplifier with the AU-111 amplifier. It consisted of a silicon npn type transistor at the input and one ECC83 section in the other. A unique and rarely used hybrid solution. The 500A model, in turn, filled the medium-power equipment segment. It had a very modern and interesting "design" (other SANSUI product, the SAX-200 model with 6BM8 / ECL82 tubes, probably produced only for the internal market, had a similar appearance). In the power stage of 500A tubes 7189A / E84L were working. The receiver shared the radio part to a large extent with the SANSUI 1000A and the TU-70 tuner. Characteristic for the 500A was a different approach to handling. The large combination of signal switching such as "left channel to mono", "stereo reverse" etc. has been abandoned and practically its source and signal switching system is the one used for the next several dozen years. Besides, the band adjustment potentiometers were coaxial integrated. The ability to adjust the bandwidth on each channel separately was a thing of the past. SANSUI also used here for the first time a corrective preamplifier entirely based on NPN silicon transistors. Almost all other models had a PNP "germanium" corrective preamplifier. The 500A model was not a successor to the 500. It is a completely different design. But the most famous SANSUI tube product is the 1000A receiver. Just like the 500A model, it was not a successor to the previous model (1000), but a completely different product. It inherited only an aluminum front from its predecessor. And that's it. The 1000A model was the largest and heaviest receiver on the US market in the years 1965-1971 and at the same time had the highest power. It easily competed with similar parameters with "made and USA" products, being at the same time a much cheaper alternative.
The SANSUI company disappeared from the market at the beginning of the 90's of the last century. Before the fall, it released a "remake" of the AU-111 amplifier with the additional name "vintage". The amplifier underwent minor modifications (CD input and tube phono stage). It was a phenomenon on a global scale for the company after 30 years returned to tube products. But it was already swan song. It collapsed shortly after that. The SANSUI tube technology left behind the transformers offered today by the Hashimoto brand.
And finally, a curiosity. Each Sansui tube product had a diagram glued to the bottom of the cage.