Sony CS-300

The Sony CS-300 Sterecorder (often simply referred to as the Sony 300) is a significant historical model. It was a high-end consumer machine from the early 1960s (circa 1961–1964) and was one of the last major reel-to-reel decks Sony produced using tube (valve) electronics before the industry transition to solid-state (transistorized) circuits.

It was marketed under the "Sterecorder" name, signifying its full stereo capability.

System Architecture: A Tube-Era Hi-Fi Deck

The CS-300 was designed as a complete hi-fi solution, featuring built-in stereo amplifiers and speakers, allowing it to function as a standalone music system.

• Electronics: Tube (Valve) Amplification. This is its defining technical characteristic. It used a complement of tubes (e.g., 12AD7, 6AU6, 6AQ5) for pre-amplification and power output.
  Audio Output: Approximately 3 watts per channel (WPC) to the internal speakers.

• Track System: Quarter-Track Stereo. This was the standard format for home hi-fi recordings, allowing four passes on a single reel of tape (Stereo Left/Right in one direction, then the tape is flipped for Stereo Left/Right in the other direction).

• Transport: Single Hysteresis-Synchronous Motor. The single motor handles the capstan drive (usually via a belt) and the winding/rewinding functions.

Tape Speeds 7 ½ ips (19 cm/s) and 3 ¾ ips (9.5 cm/s)

Reel Size Typically 7-inch maximum

Heads 2 Heads: Erase Head and a combined Record/Playback Head (Quarter-Track Stereo)

Frequency Response 50 Hz – 15,000 Hz (at 7 ½ ips)

Signal-to-Noise > 50 dB

Wow & Flutter < 0.15% (at 7 ½ ips)

Level Indication Two large VU MetersDimensions

A large tabletop unit (Approx. 16"W x 12"D x 7"H), weighing around 35 lbs.

Key Technical Features

Dual Controls and Professional Mixing

The CS-300 offered features typically found on semi-professional equipment of the era:

• Individual Channel Controls: Separate level controls were provided for the microphone, auxiliary, and playback inputs for both the left and right channels.

• Sound-on-Sound (SOS): By feeding the output of one channel back into the input of the other, a user could manually perform basic overdubbing or mixing.

Hysteresis-Synchronous Motor

The use of a Hysteresis-Synchronous motor was a hallmark of quality in this period. This type of motor runs at a constant speed determined by the AC line frequency, providing a more stable and accurate tape speed than the induction motors used in cheaper models.

Contour Switch

The deck included a "Contour" switch (often called a "Loudness" switch today) that provided an 8 dB bass boost to compensate for the ear's loss of bass perception at low listening levels. This was applied to the sound played back through the built-in monitor speakers.

Comparison and Context

The CS-300 represents the transition point from tube-powered hi-fi (like the earlier Ampex or Viking decks) to the transistor era. It offered better frequency response and dynamic range than smaller, mono decks (like the earlier CP-12), but its two-head design meant it lacked the "off-tape monitoring" capability of later Sony three-head decks (like the TC-377).

• Legacy: Its mechanical design paved the way for Sony's highly successful line of single-motor, quarter-track, solid-state decks in the late 1960s and early 1970s.