Ampex MR 70

The Ampex MR-70 is a professional master reel-to-reel tape recorder introduced around 1965, designed to meet the highest standards of performance, reliability, and operational convenience for recording studios and the music industry.

Key Technical Specifications:

• Track Systems: Available in multiple configurations — 1-track mono, 2-track stereo/monaural, 3-track multi-channel, and 4-track multi-channel versions.

• Tape Width: Supports up to 1-inch tape width depending on model.

• Tape Speeds: Standard speeds include 7½ ips, with optional 15 and 30 ips for higher fidelity.

• Frequency Response: 50 Hz to 15 kHz at 15 ips ±1 dB, and extended up to 20 kHz at 30 ips.

• Wow and Flutter: Exceptionally low at 0.05% (15 ips).

• Signal-to-Noise Ratio: Ranges from 65 dB to 70 dB depending on track configuration.

• Total Harmonic Distortion: Approximately 0.5%.

• Crosstalk: Approximately 50 dB.

• Motor and Transport: Heavy die-cast frame for precise and stable tape motion, constant hold-back tension system for uniform tape speed and alignment.

• Electronics: Nuvistor-based amplifiers for preeminent audio quality with low noise and distortion; master oscillator at 150 kHz for feedback-stabilized bias and erase amplifiers.

• Editing and Transport Features: Includes variable speed winding and rewinding (up to 400 ips) for precise locating and editing, fully automatic tape lifters, illuminated and selectable meter displays (output or erase mode).

• Dimensions: Approximately 19 x 24.5 x 12 inches (WxDxH).

• Weight: Approximately 130 lbs (59 kg).

• Power: Universal voltage transformer with configurable input voltage.

Additional Information:

• The MR-70 series included versions tailored for different numbers of tracks and tape widths, accommodating a wide range of recording applications including stereo, multi-track, and mastering.

• Built with rigorous mechanical and electronic design to ensure repeatable, stable operation and maximum fidelity.

• Offers seamless editing and operating ease for professional users.

• Functions supported include sound-on-sound recording, over-dubbing, and other studio-standard techniques.

The Ampex MR-70 is a landmark professional analog tape recorder known for its stellar audio quality, durable construction, and sophisticated transport and electronics. It is designed for master recording and multi-track mixing processes where precision and reliability are paramount. The MR-70 remains a highly respected and sought-after machine among vintage recording professionals and collectors for its unmatched fidelity, low noise, and operational versatility.

This recorder set new industry standards during its era and is considered a classic example of analog mastery tape technology.