pioneer sm-83

According to the manufacturer, the SM-83 amplifier (also known as SM-500) offered 28 W of music power per channel when loaded with loudspeakers with a resistance of 8 or 16 ohms. The power amplifier worked in a Push & Pull configuration with adjustable bias. Adjusting this parameter was common to all power lamps. Power tubes, in turn, were 7189A, a higher rated 7189. The European counterpart of these lamps were practically unavailable to ordinary users E84L lamps. Another replacement was the Soviet 6P14P with the letter "E" and another additional one. However, the use of substitutes required changing of a pinout in the tube socket. The driver tubes are the standard 6AN8 used in Japanese constructions (sometimes with the letter "A"). The preamplifiers were operated with the use of 12AX7 / ECC83 tubes. The SM-83 had bass and treble control - CH A / CHA B on separate single potentiometers (which made servicing this amplifier cheap, light and pleasant :)). The power supply was carried out on the voltage doublefier system on silicon diodes, while the voltage to the bias system was provided by a Graetz selenium bridge. This bridge also powered the series-connected incandescence of 12AX7 / ECC83 tubes in the corrective preamplifier. This system was intended for signals from a turntable with a magnetoelectric cartridge or a mechanism with tape heads. The amplifier had a light bulb with a red "window" in the central place on the front plate, informing the device was "On". The Pioneer SM-83 was and is a sought-after amplifier due to its good parameters in terms of frequency response and power. It is also fairly easy to service. The biggest problem when restoring this device is the cosmetic condition and sometimes the lack of knobs. The SM-83 model was also offered under the ITT brand as the SA-720 model.

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