The 3M Digital Audio Mastering System, introduced in the late 1970s, was the first fully integrated professional digital recording system, consisting of the DMS-32 Digital Multitrack Recorder and the DMS-2 Digital Mastering Recorder. Designed to replace analogue tape machines in studio environments, it was promoted as a true “next generation” technology, offering exceptional signal-to-noise performance, extended frequency response, and with wow and flutter described as simply “not measurable.”
The 3M Digital Audio Mastering System-32 allowed 32-track digital recording on 1-inch (25.4 mm) tape at 16-bit word length and a 50 kHz sampling rate. As 16-bit converters did not yet exist, 3M engineers cascaded a 12-bit and an 8-bit converter to produce effective 16-bit resolution. The input signal was encoded into data frames containing 16-bit words, parity bits, a cyclic redundancy check (CRC) word, and synchronisation. These frames were then recorded to tape using a delay modulation scheme optimised for data integrity. The tape transport itself was engineered with a highly precise path to ensure constant head contact, critical to preventing data loss, while each of the 32 channels had its own dedicated electronics card for calibration and stability.
On playback, the system used a dedicated decoder board that generated a tape clock and frame sync to read the data back. A crystal-controlled clock pulse corrected timing errors, while CRC checks determined if data frames were valid. If errors were detected, parity information was used to reconstruct the missing data before conversion. The corrected digital signal was then passed to the D/A converters, with transformer-coupled analogue outputs ensuring clean integration into studio consoles.
The 3M Digital Audio Mastering System-2 mastering deck, using half-inch tape, offered 2- or 4-track digital recording at the same 16-bit / 50 kHz resolution, allowing projects recorded on the DMS-32 to remain in the digital domain all the way through mixdown. Together, the two machines made it possible for the first time to track, mix, and master without any return to analogue tape.
Control was provided by a removable control unit that could be operated up to 30 feet from the transport. This unit handled all essential machine functions and indicators, with 3M emphasising that the control logic was simple and intuitive for engineers accustomed to analogue tape operation.
First tested at Sound 80 Studios in Minneapolis in 1978, the system entered limited commercial release in 1979, with installations at facilities such as Warner Bros, A&M, The Record Plant, and Sound 80. It was used on historic recordings including Ry Cooder’s Bop Till You Drop.
At a cost of over US$115,000 for the 3M Digital Audio Mastering System-32 alone, and closer to US$150,000 when paired with the 3M Digital Audio Mastering System-2, the system was prohibitively expensive and only a handful were ever built. Today, working examples are exceptionally rare. Iron Mountain maintains two operational systems and remains one of the few facilities worldwide capable of accurately transferring 3M digital tapes. Despite its short production run, the 3M Digital Audio Mastering System was a landmark in recording history, paving the way for the digital formats that followed.
Features
- 32-track digital recording on 1-inch tape
- Hybrid 12-bit + 8-bit converter system producing 16-bit resolution
- Sampling rate of 50 kHz (predating later 44.1 and 48 kHz standards)
- Highly precise tape path ensuring constant head contact
- One electronics card per track for calibration and reliability
- Data encoded with parity bits, CRC error checking, and sync for robustness
- Playback included crystal-controlled clock correction and error reconstruction
- Transformer-coupled analogue outputs for clean integration into consoles
- Removable remote control unit, operable up to 30 feet from the transport