Ampex 402

The Ampex 402 reel-to-reel tape deck is part of the Ampex Series 400 line, introduced in the early 1950s. It is a professional, half-track tape recorder designed for high-fidelity audio recording on ¼-inch wide magnetic tape, following RMA standards to allow two separate audio tracks on a single tape for efficient tape utilization.​

Key Technical Overview:

• Tape Speed: Supports 15 inches per second (ips) and 7½ ips, with motor and equalization speed switches allowing easy speed changes.

• Frequency Response: At 15 ips, approximately 30 Hz to 15 kHz ±2 dB; at 7½ ips, 40 Hz to 10 kHz ±2 dB or 30 Hz to 15 kHz ±4 dB, depending on equalization setting.

• Signal-to-Noise Ratio: Over 65 dB unweighted to maximum recording level, and over 55 dB measured by NARTB standards, including bias and erase noise.

• Wow and Flutter: Well under 0.2% RMS at 7½ ips and under 0.2% RMS at 15 ips, ensuring stable tape speed and minimal distortion.

• Playback Timing Accuracy: 0.2% (approximately 3.6 seconds drift over a 30-minute recording).

• Tape Usage: Due to half-track design, tape length is effectively doubled by recording on both halves, roughly 32 minutes per track at 15 ips on a standard reel.

• Transport Mechanism: Three motor design for capstan, take-up, and rewind with fast tape speed stabilization (less than 0.17 seconds at start) and stopping tape movement under 2 inches.

• Controls: Four pushbutton relay-operated controls for Start/Play, Stop, Fast Forward, and Rewind; separate Record button which energizes the record relay.

• Head Assembly: Single plug-in lug-in housing containing erase, record, and playback heads, facilitating maintenance.

• Remote Control Capability: Relay operation allows controls to be remotely placed.

• Weight and Size: Typical console-style dimensions, robust build for professional operation.​

The Ampex 402 was designed for broadcast and studio environments needing efficient tape usage without compromising sound fidelity, thanks to its half-track system and precise mechanical and electronic design. Its modular head design and relay-operated controls enhanced usability and serviceability.