Introduced in 1980, the Phase Linear 7000 Series Two was a microprocessor-controlled three-head cassette deck developed as a companion to the company’s Series Two audio components. Manufactured in Japan (by Pioneer, it was essentially a Pioneer CT-A1 with a stunning face) and finished in champagne gold, the Phase Linear 7000 Series Two combined a quartz-locked dual-capstan transport, separate record and playback heads, automatic MicroScan tape calibration, nine calibration memories and extensive programmable transport functions. Its substantial construction, elaborate electronic displays and concealed control panel made it one of the most technically ambitious cassette decks offered under the Phase Linear name.
The Phase Linear 7000 Series Two was designed to support Type I, ferrichrome, chromium dioxide and metal cassette formulations. Metal-tape compatibility required greater recording and erasing capability than earlier oxide formulations, and the deck incorporated recording, playback and erase heads designed to accommodate the higher magnetic requirements of Type IV tape.
The three-head system used separate record and playback gaps, allowing each to be optimised for its specific function. The arrangement also enabled off-tape monitoring, with the recorded signal reproduced by the playback head immediately after it had been placed on the tape. The operator could therefore compare the source and recorded signals while recording.
The record and playback heads used wear-resistant unicrystal ferrite material. Both heads were arranged within a compact integrated assembly that fitted through the cassette opening normally occupied by a single combined head. This construction maintained the alignment between the record and playback gaps and reduced the need for repeated record-head azimuth adjustment caused by small differences in cassette-shell geometry.
A double-gap ferrite erase head provided the magnetic flux required to erase metal-alloy tape. The separate erase, record and playback functions completed the deck’s three-head arrangement and allowed direct monitoring without compromising the design of either the recording or playback gap.
The transport used a dual-capstan configuration that isolated the section of tape passing across the heads from disturbances generated within the cassette shell and reel system. Maintaining controlled tension across the head assembly reduced modulation noise associated with longitudinal tape vibration and supported stable tape-to-head contact.
A direct-current servo motor drove the capstan system. Its rotational speed was locked to the reference frequency of a quartz-crystal oscillator, providing stable tape speed during recording and normal playback. Wow and flutter was specified at 0.03% weighted RMS.
A separate direct-current motor powered the reel hubs. The separation of capstan and reel functions reduced the mechanical compromises associated with a single-motor transport and allowed the capstan system to concentrate on maintaining accurate tape speed.
Quartz control could be overridden during playback through the front-panel pitch control. This provided approximately ±6% adjustment around normal speed, with a centre detent identifying the quartz-locked position. The pitch control could be used to match a recording to an instrument, correct material recorded at a slightly different speed or alter playback speed for specialised purposes.
All transport modes were controlled electronically through light-touch push-buttons and a solid-state logic system. Dedicated controls were provided for rewind, fast forward, stop, play, record and pause, with an individual LED identifying the selected mode. The logic system enabled smooth transitions between transport functions without requiring the operating controls to move the mechanism directly.
The lower section of the front panel was concealed by a large metal cover. Touching the cover caused it to tilt forward and slide beneath the deck, revealing the cassette-loading area, calibration controls, memory programming functions and secondary recording controls. Closing the panel gave the Phase Linear 7000 Series Two a comparatively uncluttered appearance that matched other Series Two components.
A cassette was inserted vertically with the exposed tape edge facing downwards. The cassette was held between guides, while the transport automatically removed slack from the tape after loading. The open layout also provided access to the heads and tape path for routine cleaning and demagnetisation.
An illuminated panel behind the cassette made the tape reels visible during operation. Markings at each side provided an indication of the quantity of tape remaining and warned when approximately two or three minutes remained on the current side.
The MicroScan automatic calibration system adjusted the Phase Linear 7000 Series Two for the individual cassette loaded into the transport. Although tapes were divided into basic formulation classes, differences in sensitivity, bias requirements and high-frequency response existed between manufacturers and individual product ranges. MicroScan was intended to compensate for these differences automatically.
Pressing the MicroScan control placed the deck into its calibration routine. The microprocessor first tested 64 recording-bias values and selected the setting appropriate to the tape. A dedicated Bias indicator flashed while this process was taking place.
The system then adjusted recording sensitivity so that the level reproduced from the tape corresponded with the required reference. The Level indicator showed this stage of the calibration process.
A further test compared the recorded response at 10kHz with the response at 400Hz. The microprocessor adjusted record equalisation until the required relationship was obtained, with the EQ indicator identifying the process.
Once bias, level and equalisation had been calibrated, the three status indicators remained illuminated. The deck then rewound automatically to the position at which calibration had begun. The complete procedure required approximately 40 to 50 seconds, and the calibration signals were subsequently erased when normal recording commenced.
The calculated bias, sensitivity and equalisation settings could be stored in any of nine tape memories. Each memory could therefore retain the calibration data for a particular brand and formulation. When the same tape was used again, pressing Recall and the appropriate numbered memory button restored the stored parameters without requiring another complete calibration cycle.
Backup batteries retained the stored MicroScan data when the cassette deck was switched off. A dedicated front-panel indicator warned when these batteries required replacement. The battery compartment was positioned on the rear panel.
Manual bias adjustment was also provided. The centre-detented control allowed the automatically selected or standard bias point to be altered when the operator required a different recording characteristic.
Four tape-type settings covered standard ferric, ferrichrome, chromium dioxide and metal formulations. Separate status indicators showed the selected formulation. The tape selector established the basic recording and playback conditions, while MicroScan refined the deck’s settings for the individual cassette.
The Phase Linear 7000 Series Two included Dolby B noise reduction. A dedicated switch and status indicator showed when the system was active. Signal-to-noise ratio was specified at 70dB with Dolby B engaged.
A switchable MPX filter removed the 19kHz pilot tone present in FM stereo broadcasts. This prevented the pilot signal from interfering with the Dolby noise-reduction circuit when recording from an FM tuner. The filter could be switched off when recording other sources.
A tape and source monitor selector worked with the three-head system. Source monitoring allowed the operator to hear the incoming programme, while Tape monitoring reproduced the signal from the playback head immediately after recording.
The line and microphone inputs could be mixed. Separate dual-concentric controls adjusted the left and right microphone and line-input levels, allowing both source types to be combined without an external mixer. The microphone inputs accepted nominal signals of 0.3mV, while the line inputs accepted approximately 63mV.
A separate output-level control adjusted the playback signal, headphone level and fluorescent meter indication. The control included a detent at its standard operating position.
The fluorescent level display covered a range from -30dB to +8dB. Its two-colour presentation made normal and high-level indications readily distinguishable, while dedicated operating modes allowed the display to be matched to different recording requirements.
Peak mode provided a fast indication of transient signal levels. Peak Hold retained the highest detected peak so that short overloads could be identified after they had occurred. Average mode produced behaviour closely corresponding to that of a conventional VU meter.
Bright and Dim controls changed the illumination intensity of the display. This allowed the meter brightness to be adjusted for different room-lighting conditions without affecting the underlying recording-level indication.
The display was calibrated so that +3dB represented Dolby level when the playback output control was at its centre-detented reference position. Measured indication accuracy remained within approximately ±1dB down to -20dB.
A four-digit electronic tape counter replaced the conventional mechanical counter. It worked with the memory and repeat controls to identify stored tape positions and automate return, playback and repetition functions.
Memory Stop could return the tape to the counter position at which the counter had been reset and stop the transport. Memory Play returned to the same position and began playback automatically.
Memory Repeat allowed a selected section to be reproduced repeatedly. The beginning and end of the passage could be established through the counter and memory controls, after which the deck automatically returned and replayed the chosen section.
End Repeat operated in relation to the end of the cassette rather than an intermediate counter location. The memory and repeat status was shown by dedicated indicators in the upper display area.
A timer-control section allowed the Phase Linear 7000 Series Two to be prepared for automatic recording or playback through an external mains timer. Separate controls selected the required timer operating condition.
Record Mute inserted a silent section while the tape continued to move in record mode. Its indicator flashed while muting was active, allowing clean gaps to be created between recorded selections without stopping the transport.
The front panel provided separate left and right microphone sockets together with a headphone output. The headphone amplifier produced sufficient level for both 200Ω and 600Ω headphones during testing.
The rear panel included line inputs and outputs together with a second set of connections intended for direct linking to another recorder. An unswitched AC outlet rated at 300W was also provided.
Laboratory testing demonstrated that the MicroScan system could obtain consistent results from a broad selection of ferric, chromium dioxide-position and metal tapes. Ferrichrome proved more difficult for the automatic system to resolve, but the deck’s standard and manual facilities remained available for that formulation.
Using ferric, chromium dioxide-position and metal cassettes, measured record and playback response remained within approximately ±1.5dB from 30Hz to 18kHz, extending to 20kHz with metal tape. The published frequency response was specified as 25Hz to 19kHz with metal tape.
Measured record and playback distortion varied according to tape formulation. Figures included 0.55% with 3M Metafine metal tape, 0.85% with Maxell UD XL-II, 0.5% with Maxell UD XL-I and 1.1% with Sony ferrichrome tape. The specified total harmonic distortion was 1%.
The 3% distortion reference level was not reached until inputs of +7dB with 3M Metafine, +4.8dB with Maxell UD XL-II, +7.5dB with Maxell UD XL-I and +6dB with Sony ferrichrome. These results demonstrated substantial recording headroom across the tested formulations.
Unweighted signal-to-noise figures without Dolby measured 56dB with 3M Metafine, 52.6dB with Maxell UD XL-II, 55dB with Maxell UD XL-I and 53.5dB with Sony ferrichrome. With Dolby B and CCIR weighting, the corresponding figures were 69dB, 65dB, 64.5dB and 68dB.
Wow and flutter measured 0.03% weighted RMS after recording and reproducing a 3.15kHz test signal. DIN peak-weighted measurements produced figures between 0.04% and 0.05%.
Fast-forward time for a C-60 cassette measured 77 seconds, while rewind required 75 seconds. Tape movement and mode changes were handled through the solenoid-operated logic transport.
A 68mV signal at the line input produced a 0dB meter indication, with the output measuring 460mV. Microphone-input sensitivity measured 0.27mV, and no overload was detected until the microphone input reached 65mV. Additional microphone-input noise at maximum gain measured only 2.5dB.
The Phase Linear 7000 Series Two was manufactured in Japan from 1980 to 1983. It used 194 transistors, 124 diodes and 42 integrated circuits, reflecting the extensive analogue, display, logic and microprocessor systems contained within the deck.
Its champagne-finished cabinet measured approximately 217mm high, 480mm wide and 425mm deep and weighed 18.2kg. The large enclosure accommodated the concealed control panel, dual-capstan transport, electronic displays, extensive calibration system and associated power supplies.
The Phase Linear 7000 Series Two represented the most elaborate cassette recorder offered under the Phase Linear name. Its MicroScan calibration processor, nine tape memories, three-head monitoring, quartz-locked dual-capstan transport, programmable repeat functions and extensive metering placed it among the most highly automated cassette decks of its period.
Features
- Three-head cassette recording and playback system
- Separate record and playback gaps within an integrated head assembly
- Wear-resistant unicrystal ferrite record and playback heads
- Double-gap ferrite erase head
- Off-tape monitoring during recording
- Dual-capstan tape transport
- Quartz-locked direct-current servo capstan motor
- Separate direct-current reel motor
- Solid-state logic transport control
- Light-touch transport push-buttons
- MicroScan automatic tape calibration
- Automatic recording-bias adjustment through 64 steps
- Automatic recording-level calibration
- Automatic record-equalisation calibration
- Approximately 40 to 50-second calibration cycle
- Nine calibration memories
- Calibration-data recall
- Manual fine-bias adjustment
- Dolby B noise reduction
- Switchable 19kHz MPX filter
- Microphone and line-input mixing
- Separate left and right microphone and line-level adjustment
- Adjustable playback output level
- Playback pitch control with approximately ±6% adjustment
- Four-digit electronic tape counter
- Memory Stop function
- Memory Play function
- Memory Repeat function
- End Repeat function
- Timer-controlled recording and playback
- Record Mute with flashing status indicator
- Two-colour fluorescent level display
- Peak level-display mode
- Peak Hold level-display mode
- Average level-display mode
- Illuminated cassette compartment
- Automatic cassette slack removal
- Remaining-tape indication behind the cassette
- Concealed sliding lower control panel
- Separate left and right microphone inputs