Sansui TC-505 (1968)

The Sansui TC-505 came out in July 1968 at ¥37,500. It is a stereo preamplifier with a built-in AM/FM tuner, called a "tuner/control amplifier" in the terminology of the day. It appears to have been sold only in Japan, and there is little documentation beyond the original spec sheet. What the record does show is a well-engineered unit that bridged Sansui's tube heritage and its solid-state future.

The FM section uses an FET in the RF stage with a 3-row varicon front end, a 4-stage IF amplifier, and a 3-stage limiter. Sansui left out the AFC circuit entirely. Instead it temperature-compensated the oscillator and stabilized the power supply with Zener diodes, which was a confident choice for 1968. The noise canceller avoids the usual high-cut approach and removes FM noise without chopping the audible highs. A 35 dB separation multiplex circuit and pure electronic stereo/mono switching finish off the tuner.

The preamp side is all-silicon, with low-noise transistors throughout and NF-type circuitry from the phono equalizer (RIAA) through the tone control stage. The headphone jack has its own independent booster, so it could double as a monitor output. The front panel carries bass (±12 dB at 50 Hz), treble (±10 dB at 10 kHz), loudness, low and high filters, and a four-position selector (Phono, FM AUTO, AM, AUX). Total semiconductor count is 28 transistors, 20 diodes, 1 FET.

One dealer description of a surviving unit praised it for retaining "tube-like qualities" with a warm, natural soundstage. That is a subjective note, but it fits how early solid-state Sansui designs are often remembered. A schematic and Japanese service manual circulate among collectors. The dedicated wood case (C-9) was sold separately.

Known specifications: