Nagra Model T

If the Nagra IV-S is the king of portable field recorders, the Nagra Model T-Audio (often simply called the "Nagra T") is the emperor of the studio. Introduced in the early 1980s, the T-Audio represented a radical departure from the company's famous portable lineage. It was designed as a transportable, heavy-duty mastering and editing deck, built to compete with the Studer A80 and A820, but with a unique mechanical philosophy that arguably surpasses them both.

The T-Audio is widely considered one of the most mechanically sophisticated tape transports ever built.

The defining feature of the Nagra T is its tape handling. While the IV-S used a closed loop, the T-Audio perfected it for high-speed shuttling and editing. 

The T-Audio employs a dual-capstan system with 4 direct-drive independent motors to ensure stable tension and minimal wow/flutter, handling master tapes delicately for studio-grade performance. It supports trolley mounting for mobility in professional environments and uses NAB hubs with adapters for various reel sizes.​

• Twin-capstan design prevents tape stretch and provides closed-loop tension control.

• Reels up to 10.5 inches (26.7 cm) in diameter.

• Mechanical precision inherited from Nagra's field recorders but scaled for studio reliability.

• The Scanner System: Instead of standard tension arms, the T-Audio uses a unique "Scanner" assembly on the left and right. These are rollers mounted on precision sensors that constantly measure tape tension and speed.

• Tape Handling: This system allows the Nagra T to handle tape more gently than perhaps any other machine.
  Speed: It can shuttle tape at 10 meters per second (very fast) and stop instantly without stretching or snapping the tape.
  Loading: The tape path is completely open. When the machine is stopped, the capstan pinch rollers retract, and the tape guides open up, allowing the tape to be lifted straight off—a dream for editing.

• Interchangeable Head Block: The entire head assembly is modular and can be swapped quickly. This allowed users to switch between stereo (0.75mm track separation) and two-track with center timecode, or even 4-track configurations on some versions.

Speeds and Equalization

Programmable via front-panel keypad and internal dip switches, the T-Audio allows up to four user-selected tape speeds and corresponding EQ curves for compatibility with diverse tape formulations. 

• Customizable speed/EQ combinations for optimal bias, HF response, and noise floor.

• Supports extended play at lower speeds without compromising quality.

• Timecode variants add SMPTE/EBU sync tracks.

The Nagra T was one of the first machines to heavily integrate microprocessor control into the transport logic while keeping the audio path purely analog.

• Speeds: 3.75, 7.5, 15, and 30 ips (inches per second). The 30 ips capability clearly marked this as a mastering-grade studio machine.

• Servo Control: The microprocessor monitors the tension sensors and adjusts the reel motor torque thousands of times per second. This results in:
  Constant Tension: Tape tension remains perfectly constant from the beginning to the end of the reel, regardless of spool size.
  Wow & Flutter: Virtually unmeasurable (typically < 0.03% weighted).

• Variable Speed: The transport features a massive variable speed range, allowing for precise pitch shifting or extreme slowing down for audio analysis.

While the transport is the star, the audio electronics are consistent with Kudelski’s high standards—ultra-clean, neutral, and precise.

• Symmetry: The audio circuits are fully balanced and floating.

• Equalization: Like the IV-S, it supports NAB and CCIR (IEC) standards, switchable from the front panel. It also features the proprietary NagraMaster EQ at 15 ips for optimized dynamic range.

• The "Keyboard": The control panel is distinct, featuring a detachable keypad interface (often connected via a coiled cord) that controls all transport functions, allowing the machine to be rack-mounted while the controls sit on a console.

• Editing Features: It includes a dedicated "splicing block" area and an integrated cutter (on some models). The "search to zero" and locator functions were advanced for an analog machine, utilizing the timecode capabilities.

The "T" in T-Audio implies its deep integration with Timecode. It was the industry standard for post-production transfer (telecine).

• SMPTE/EBU Integration: The machine has a dedicated third track (in the center of the tape, between the stereo audio tracks) specifically for SMPTE/EBU timecode.

• Synchronization: It could lock to external video references (House Sync) with incredible speed and stability. This made it the bridge between film sets (where audio was shot on a Nagra IV-S) and the editing suite.