pioneer sx-800

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The SX-800 was top-notch equipment. Visually similar to the ER-420, but structurally more advanced and with more power output. Modern design, extensive tuner automation and high output power were to place the 800 parallel to the 110 model in the segment of high-power receivers. The SX-800 was to compete with the Sansui 500A. The modular FM head with the symbol AM-0120 operating in the range of 88-108 MHz contained two tubes - the 6CW4 nuvistor in the input circuit and one 6AQ8 / ECC85. After the head there was a four-stage intermediate frequency amplifier. The next element of the tuner was a modular stereo decoder with the symbol AM-0109 built on three tubes - one 6AN8A and two 6AQ8 / ECC85. The module was complemented by a 2SB54 transistor used to control the relay that turns on the 6.3V light bulb - MPX stereo indicator. It was placed in the lower part of the scale on the front of the receiver. Symmetrically there was a mechanical tuning indicator. The receiver also had an AM section for medium waves. The equalizing preamplifier was a standard Pioneer design found in other models to amplify signals from turntables and the tape head. One 12AX7 / ECC83 per channel was used for this. Between the power amplifier and another 12AX7 there was a bass and treble band control as well as low-cut and high-cut filters. The SX-800 model, however, had a different "philosophy" of adjusting in the front panel. The volume and balance knobs were separate, and band controls were grouped into "treble-bass" sets for each channel separately. Standard monophonic potentiometers were used. On the front, apart from the input switch, there was also a rotary switch for changing channels, monophonization or selecting monophonic L or R channels. The power amplifier is based on 7189A / E84L tubes. 6AN8A was used as drivers. The amplifier worked in a Push & Pull configuration with adjustable bias. According to the manufacturer, it provided 2 x 25 W of musical power per channel. The power supply was based on a voltage doubler on silicon diodes. The front panel was aluminum with an additional black-colored aluminum plate. Of course, the metal frame completed the whole. Pioneer also released the SX-800A model, sometimes referred to as the SX-2000. It was an almost identical design to the 800, except that the 7189A tubes were replaced by the 7868 and a modified version of the MPX decoder module with the symbol AM-0129 was used. The power of the amplifier has increased.

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