pioneer sx-110

Pioneer SX-110 was to be the receiver with the highest power, very good parameters of the tuner and generally compete with the Sansui 1000A in terms of parameters. Perhaps it was successful, but the SX-110 models were sold many times less than 1000A. The power amplifier worked on 7868 tubes in a Push & Pull arrangement with adjustable bias, delivering according to producer's total of 110 W of musical power. The bias voltage was fixed, but there was a regulation of the balance of this voltage. This was facilitated by the fact that a 20 ohm resistor was placed in the cathode circuits, which made it possible to measure the lamp current. The tubes 7868 were were in a matter of fact 7591 tunes with a different base - novar - similar to noval but slightly larger diameter. The usual driver tubes are 6AN8. The FM head operating in the 88-108 MHz range contained three tubes - one 6CW4 nuvistor and two 6AQ8 / ECC85, of which one ECC85 section worked in the AFC (Automatic Frequency Control). There was, after the head, a three-stage intermediate frequency amplifier (the Sansui 1000A and 500A had four stages). The next element of the tuner was a stereo decoder on three tubes 6CG7, 6AQ8 / ECC85 and 6AV6 / EBC91. The tuning indicator was a common for Pioneer "magic eye"  6R-E13, and the MPX signal was declared by a neon lamp. The receiver also had an AM section for medium waves. The preamplifier was a standard Pioneer design found in earlier models. One 12AX7 / ECC83 per channel was used to amplify the signals from the turntables and the tape head. There was a balance and volume control as well as a low-cut filter, high- cut filter and loudness between the power amplifier and another 12AX7. The bass and treble band adjustments as well as the high-cut and low-cut filter preceded the aforementioned ECC83. The voice and balance controls were placed in one three-elements potentiometer, with one inner axis controlling the volume and the other the balance. Bass and treble adjustments were also made on double coaxial potentiometers. This made it possible to independently adjust each channel. 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 front panel was aluminum with a metal frame around it. Prints of functions, switch and adjustment in black paint on the front. Visually, the receiver looked very nice and gave the impression of being quite low. But it was an impression. Thanks to the use of 7868 tubes, the height of the structure was lowered, but the SX-110 stood on very high feet, because the heat emitted from the 110 W of power had to be dissipated. The price for the lower height was the extension of the equipment depth by nearly 5 cm compared to 1000A.

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