Sony TC-366-4

The Sony TC-366-4 (often marketed as the TC-366-4 Quadradial Stereo Tape Recorder) is a historically significant reel-to-reel deck from the early 1970s. It is essentially a specialized version of the popular TC-366, dedicated to the quadraphonic (four-channel) format that Sony actively promoted.

This deck was designed to bring the experience of 4-channel surround sound recording and playback to the consumer market.

Key Specifications

• Tape speeds: 7½ ips (30 Hz–20 kHz ±3 dB), 3¾ ips (30 Hz–17 kHz ±3 dB) and 1⅞ ips

• Track system: 4-track, 4-channel stereo/multichannel

• Heads: 4 (1 erase, 1 record, 1 playback, Q-Erase (Quad Erase)

• Reel size: Up to 7 inches

• Motors: 1

• Wow and flutter: 0.09% (7½ ips), 0.12% (3¾ ips)

• Signal-to-noise ratio: 55 dB (SLH tapes), 52 dB (standard)

• Total harmonic distortion: 1.2%

• Bias frequency: 125 kHz

• Inputs: Mic 0.19 mV (600 Ω), aux/line 60 mV (100 kΩ)

• Outputs: Line 0.775 V (100 kΩ+), headphone 30 mV (8 Ω)

• Semiconductors: 27 transistors, 4 diodes

• Dimensions: 432 x 476 x 241 mm (17 x 18¾ x 9½ inches)

• Weight: 12.8 kg (28.2 lbs)

Quadraphonic Features and Design

• Four-Channel Recording and Monitoring: The dedicated quad heads allow the user to record all four channels simultaneously. Crucially, it supported Off-Tape Monitoring for all four tracks, allowing for real-time verification of the recording quality.

• Four VU Meters: Features four illuminated VU meters to independently monitor the recording and playback levels for all four channels (Front Left, Front Right, Rear Left, Rear Right).

• Built-in Amplification: The "Tapecorder" designation implies that it contains built-in record and playback amplifiers for all four channels. While it would typically be connected to an external Quadraphonic Amplifier/Receiver and four speakers for full sound, it could often function as a basic playback unit itself.

• Mixing Capability: Provided separate input level controls for each of the four channels, allowing complex mixing of multiple sources (e.g., microphones, line inputs) for quad recording.

• Stereo Compatibility: The deck can be switched to operate in standard 2-channel stereo mode, reading or recording only the two stereo tracks on the tape.

• Advanced Transport Features: Like the standard TC-366, it includes the Scrape Filter to reduce tape modulation distortion and help achieve the decent Wow and Flutter specification.

Priced at $480 new, this consumer quad deck included automatic shut-off and tape selector. Its rarity stems from limited quadraphonic market adoption, making it a collector's item for multichannel analog enthusiasts despite moderate fidelity (6/10 rating).

Vintage Maintenance Notes

The TC-366-4 shares the same mechanical platform as the TC-366, meaning it is subject to the same common issues:

1. Sticky Grease: The original white lithium grease in the transport mechanism hardens over time, requiring a full mechanical disassembly, cleaning, and re-lubrication to ensure smooth and accurate tape handling, particularly for the pinch roller and speed change linkage.

2. Belts and Idlers: Replacement of the rubber drive components is a standard requirement for restoring performance.

The TC-366-4 is a prized collector's item today, as it represents Sony's strong push into the immersive but ultimately short-lived quadraphonic format of the 1970s.