The Alpine AL-85 was the companion model to the flagship Alpine AL-90. It shared much of the AL-90’s transport, head system and operating architecture, but replaced the fully automated B.L.E.S. recording calibration computer with comprehensive manual calibration controls intended for users who preferred direct adjustment of bias, recording level and equalisation.
The Alpine AL-85 used the same direct-drive closed-loop dual-capstan transport as the AL-90. Its three-motor arrangement combined a servo-controlled direct-drive capstan motor, a separate reel-drive motor for winding functions and another motor for the electronically controlled transport mechanism. Feather-touch controls operated the transport functions.
The closed-loop dual-capstan mechanism maintained tape tension and stable contact between the tape and heads. The Alpine AL-85 achieved a specified wow and flutter figure of 0.022% WRMS, matching the Alpine AL-90.
The three-head system used separate recording and playback heads within a single assembly, permitting direct tape/source monitoring. Alpine used a Sendust recording head with a 3μm gap and a ferrite playback head with a 0.8μm gap. The narrow playback gap was selected for high-frequency reproduction, while the Sendust recording head provided the magnetic properties required for recording over a wide dynamic range.
The erase system used a dual-gap Sendust and ferrite junction head. The head assembly was developed to maintain accurate azimuth alignment, tracking and tape contact.
The principal distinction between the Alpine AL-85 and AL-90 was the recording calibration system. The Alpine AL-85 used Alpine’s M.O.R.C., or Professional Manual Optimum Recording Calibration, arrangement. Rather than allowing a computer to perform the adjustments automatically, the AL-85 provided separate manual controls for bias, recording level and equalisation.
An internal test oscillator generated 1kHz and 12.5kHz signals. These could be recorded and monitored through the deck’s three-head system while the operator adjusted the calibration controls. Separate controls were provided for the left and right channels, allowing differences between channels and cassette characteristics to be corrected individually.
The three-way calibration arrangement allowed bias, level and equalisation to be optimised together. Adjusting bias and recording level alone could leave equalisation fixed, preventing the three parameters from being aligned simultaneously. By making equalisation adjustable as well, the AL-85 allowed the frequency response and distortion characteristics of different cassette formulations to be balanced more precisely.
The wider available bias adjustment range also allowed deliberate underbiasing or overbiasing. Overbiasing could reduce harmonic distortion at the expense of high-frequency response, while underbiasing could extend high-frequency headroom with some increase in distortion.
The Alpine AL-85 used FET-equipped amplifier circuitry with direct coupling between the tape head and amplifier. Low-noise FETs were used within the equaliser amplifier and mixer stages, while electronic DC switching reduced the need for additional wiring and mechanical contacts in the signal path. The circuit arrangement was intended to reduce noise and improve frequency linearity.
Separate level controls were provided for microphone inputs and line inputs, with a master control governing the overall recording level and fade-in or fade-out operation. This arrangement also allowed microphone and line sources to be mixed. Separate output-level adjustment was provided for playback.
The recording-level meters could be switched between Peak and VU operation. The calibrated scales allowed precise recording-level adjustment for different programme material and tape formulations.
The Alpine AL-85 incorporated Dolby B and Dolby C noise reduction, together with a defeatable MPX filter. A four-digit multi-memory tape and time counter supported auto-play and auto-rewind. Pitch control allowed tape speed to be varied by up to ±6%, corresponding to approximately one semitone.
Auto Space could insert a three-second blank interval during recording by pressing the pause and record-mute controls together. Cue and review allowed recorded passages to be monitored while the tape moved in rewind or fast-forward by operating play together with the appropriate winding control.
Additional functions included timer-assisted recording and playback, microphone mono operation, a headphone output and compatibility with an optional remote-control unit. A microphone connected to the left-channel input could be recorded on both stereo channels. The AL-85 could also be fitted with an optional rack-mounting kit for installation in a standard 19-inch EIA rack.
Features
- Three-head Sendust and ferrite head system
- Separate recording, playback and erase heads
- Professional tape and source monitoring
- Three-motor transport
- Direct-drive closed-loop dual-capstan mechanism
- Computer-controlled tape transport functions
- Feather-touch transport controls
- Professional Manual Optimum Recording Calibration
- Separate left and right bias calibration
- Separate left and right recording-level calibration
- Separate left and right equalisation calibration
- Built-in 1kHz and 12.5kHz test oscillator
- Dolby B noise reduction
- Dolby C noise reduction
- Switchable Peak/VU meters
- Separate master, line and microphone recording-level controls
- Microphone and line-source mixing
- Direct-coupled FET amplifier circuitry
- Electronic DC switching
- Defeatable MPX filter
- Four-digit multi-memory tape and time counter
- Auto-play and auto-rewind
- Pitch control with a ±6% adjustment range
- Auto Space function
- Cue and review functions
- Timer-assisted recording and playback
- Microphone mono recording facility
- Variable output level
- Optional remote-control unit
- Optional rack-mounting kit