Otari MTR-90III Multichannel Tape Recorder

Message Board - Otari Otari MTR-90III General Discussion

The Otari MTR-90III Multichannel Tape Recorder records and reproduces 2" master tapes in a 24-track format. Tension is distributed uniformly across the tape surface by a pair of wide diameter pinchrollerless spindles, the capstan and the tachometer. This design eliminates contact between the tape drive and the oxide, allowing safe handling of valuable master tapes.

Mechanical integrity and long-term stability are ensured by a massive, precision top plate and a unitized, welded steel chassis. The newly designed High Speed Motor Drive Amplifier features self protection and reel-end deceleration for better tape manipulation and more efficient editing. High torque DC servo reel motors provide fast winding even with 14" reels, and ensure rapid start-ups to full stable record/play speed. The entire machine is modular in construction, including the computerized transport control logic, for high reliability and serviceability.

The MTR-90III is loaded with convenient features such as selection of external speed reference, vari-speed, or 2 crystal-locked speeds - 15/30 ips (38/76 cm/s) or 7.5/15 ips (19/38 cm/s). The reels can be gently rocked back and forth for editing with the easy-to-use Cue Wheel or by hand by turning the capstan. Push buttons also provide for tension release and retraction of the motor-driven head shields to expedite editing. A practical splicing block and a spot erase function for erasure of unwanted tracks are also provided in front of the head assembly.

The electronics are highly refined. A single PCB assembly approach has been used for the record/play audio and bias PCB assemblies for each channel simplifying setup and service. Active mixing of audio and bias in the record circuitry, proper utilization of high slew rate IC op-amps, and discrete components at critical stages ensure the cleanest and quietest recordings. There are, of course, individual channel calibrations for bias, low and high speed EQ and gain, and a low and high speed record PHASE COMP trimmer for improving complex waveform characteristics. In addition, a 3-position Master BIAS SELECT switch (with 3 corresponding trimmers) enables the entire machine, once aligned, to be rapidly switched to accommodate the bias requirements of different tapes. For further convenience, a single test input jack applies test/alignment signal to all inputs. There is automatic switching between sync reproduce and input monitor when the machine is switched between play and stop, fast winding modes, and of course Rec/Ready to record enable. DIP switches on the transport control PCB assembly permit these logic functions to be changed to suit the preference of the user.

Stable ACTIVE BALANCE circuitry has been used in the input circuit. In the output circuit, balanced or unbalanced operation can be selected. (Transformer output or input may be ordered separately.) In addition, a SERIAL I/O CONNECTOR, conforming to the RS232 standard for direct communication with a computer, and an Otari standard parallel I/O interface are provided for extended external control.

The model CB-147 Remote Control Unit is included as standard equipment. It features the same transport control buttons as the MTR-90III and provides individual function selections for each channel (Repro/Sel-Rep/Input), master function selections for all channels at once (All Inputs/All Sel-Rep/All Repro), and a master "All Safe" function. Also located on the Remote Control Unit are a Speed Reference Selector switch (VARI, FIX, EXT), a Pitch Control knob, and a Digital Readout indicating speed in percentage or inches per second (ips).

The optional CB-148 Auto Locator with a built-in stop watch attaches to the same stand as the CB-147 and provides independent readouts and controls for the elapsed tape time and locate time. The locator also features zero cue, 10 keyboard assignable memories (keyboard or direct tape time memories) with direct recall, a shuttle function for repeating any desired segment of the tape, and other time saving functions.

The optional EC-101 Plug-in Chase Synchronizer allows the MTR-90III to be controlled via SMPTE/EBU timecode for slave operation. With the optional CB-121 Synchronizer Remote Control Unit, the EC-101 can input TC offset as well as monitor master TC, slave TC and difference of timecodes.