The OPTONICA RT-6905 from 1980 is basically a one box combination of the Optonica RT-9100H cassette deck and AD-200TH programmable quartz timer unit. The cassette deck section features a 2-motor, dual-capstan, closed loop drive system that provides constant back tension on the tape for optimum tape-to-head contact, quartz -locked PLL servo capstan motor that ensures super-accurate tape speed, and Optonica's new microcomputer -controlled tape tension adjustment system that automatically optimizes tape tension before all playback operations. The Optonica RT-6905 uses a 4-head system with Dual Sendust recording, playback and monitoring (APMS sensing) heads. Test tones are provided for adjusting record sensitivity and bias, used in conjunction with the level display and the tape/source monitor switch. Then, to maximize user control, this unit provides Sharp's unique APMS (Auto Programmable Music Selector) to allow complete freedom in programming tape selection playback order, plus APSS (Auto Program Search System) for one-touch skipping and repetition of songs.
In the lower section can be found a programmable quartz timer unit with programming capacity of up to 42 automatic operations per week (absentee recording and musical alarm set-ups). There is a special synchronization of the cassette running time counter with the tape transport mechanism. The time counter can be used to keep track of either the running-time or the remaining-time of a cassette and includes a pause function that stops the counter during breaks. An infrared remote control is also provided for seat-side control of all tape transport functions, including recording and APSS, while additional rack handles were sold separately. Manufacturer's specifications. Frequency response 30 Hz to 20 kHz with Metal tape, Flutter 0.038 percent W rms, Dimensions 430 (W) x 211 (H with adjustable legs) x 371 (D) mm, Weight 15.8 kg. Original sale price 1,600 USD.
