Pioneer sm-g205
The SMG-204 model took its place right after the SM-B2xx models on the 6BM8 / ECL82 tubes, and before the SM-Q2xx models on the 6BQ5 / EL84 tubes. It had a very specific design dating back to the 50's. The front is a thin metal sheet varnished in a dark color, plastic knobs with metal finishes. Two separate scales - because the receiver worked in the multicast system. One scale / tuner for the AM band (medium or short wave selectable), the other for the FM / AM band (FM and medium wave). Each tuner had a separate 6E5 "magic eye" lamp. Such a lamp also worked in European products, and it was produced, among others, under the symbol 6E5S in the Soviets. The receiver was also adapted to work with an external MPX stereo decoder. On the back there was an integrated MPX signal output and inputs for two signals from the decoder - MXA-1A or MXA-3A. Despite the fact that the FM head had only two tuned circuits, it worked on two 6AQ8 / ECC85 tubes, one section of which was, interestingly, untuned (aperiodic) preamplifiers. AM tuners did not have ferrite antennas and required an external antenna, e.g. a parometer cable. The SM-G204 has an input for a magnetoelectric turntable on two 12AX7 / ECC83 tubes. The power amplifier is driven by double 6GW8 / ECL86 tubes working in the Push & Pull system with automatic bias. The 6GQ8 / ECL86 tubes were then almost a novelty and only Pioneer produced devices based on them from Japanese manufacturers. The others were satisfied with the 6BM8 / ECL82 and they did not use the 6GW8 / ECL86 designs. The 6GW8 / ECL86 amplifier allowed to obtain powers similar to the 6BQ5 EL84 amplifiers with a significant reduction in production costs. The first Pioneer SM-B2xx and SM-G2xx receivers, apart from 6GW8 / 6BM8 /ECL* double tubes, were also equipped with a half-wave rectifier based on a 5AR4 / GZ34 duodiode tube. The power supply in such a system was much more efficient than the commonly used voltage doublers, but it required a more expensive transformer (with a higher output voltage). Pioneer products were also characterized by the integrated coaxial potentiometers. Most often, voice control was combined with balance, and it was mechanically like that on the inner axis was controlled with a double voice potentiometer, and the outer axis was controlled with a single balance potentiometer. The knob was two-piece, wide, closer to the front it was a balance, and the narrower one above it regulated the volume. The integrated bass / treble potentiometer is similarly constructed. There are four potentiometers connected by two on one axis. The outer knob is used to regulate the bass, and the inner, narrower knob is used to regulate the treble. The preamplifier also offered a high-cut filter - "scratch", and a low-cut filter - "rumble". An additional switch physiologically raised the sound - "loudness" .
The SMG-204 was a device with a very nice "appearance" supported by simple and well-functioning electronics. Despite the seemingly low power - about 2 x 10 W - it was able to amaze the audience with the right loudspeakers. Nowadays, the SMG-204 has one more advantage. It is difficult to find a second such device within a radius of several hundred kilometers. 





     

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