Introduced in 1977, the TEAC AL-700 was a three-head, three-motor stereo recorder designed for the ELCASET format. TEAC applied technology associated with its professional and instrumentation recorders to create a substantial domestic machine combining the handling convenience of a cartridge with 6.35mm tape running at 9.5cm/s. The TEAC AL-700 used separate erase, record and playback heads, a closed-loop dual-capstan transport, independent reel motors and Dolby noise reduction, placing it among the most extensively engineered Elcaset recorders produced during the format’s brief commercial life.
The Elcaset system used tape of the same 6.35mm width employed by open-reel recorders, enclosed within a large cartridge intended to simplify loading and protect the tape during handling. Its 9.5cm/s operating speed was twice that of the compact cassette, while the larger tape area provided greater recorded track width. The TEAC AL-700 supported LC-60 and LC-90 Elcaset cartridges and accommodated Type I, Type II and Type III tape formulations.
The TEAC AL-700 employed a four-track, two-channel stereophonic recording format. Separate erase, record and playback heads provided genuine off-tape monitoring, allowing the recorded signal to be checked immediately through the playback head while recording. This arrangement also allowed the record and playback sections to be optimised independently rather than requiring a combined record and playback head.
Its transport used three motors. A frequency-generator servo-controlled DC motor drove the capstan system, while two coreless DC motors independently powered the left and right reel tables. This configuration reduced the mechanical complexity and loading associated with a single-motor transport, allowing the capstan and reel functions to be controlled separately.
The closed-loop dual-capstan system held the tape between two capstan and pinch-roller assemblies. A controlled difference between the capstan speeds maintained tension across the head area, helping isolate the tape from vibration and disturbances generated by the cartridge and reel system. The mechanism used two capstan belts and incorporated an air-damped flywheel arrangement to support stable tape travel.
TEAC also used self-aligning pinch rollers and a semi-fixed head mounting system within the transport. The pinch-roller assemblies were designed to align with the capstan shafts, while the head assembly incorporated dedicated tape guides and adjustment points. These mechanical provisions were intended to maintain consistent tape positioning across the erase, record and playback heads. The transport was controlled through large front-panel keys for record, record mute, pause, rewind, fast forward, play and stop. Electromagnetic solenoids operated the transport functions, while indicator lamps showed the selected recording modes. A separate eject control released the Elcaset cartridge from the front-loading holder.
A photoelectric end-sensing system detected the transparent leader incorporated into the Elcaset cartridge. When the clear section reached the sensor, the transport automatically stopped. The service system allowed the end-stop timing to be adjusted independently for normal play and fast-wind operation. The TEAC AL-700 included a memory control with stop, off and play positions. Used with the mechanical tape counter, this allowed the deck to stop or enter playback when returning to a selected position. A timer selector provided record, off and play settings for use with an external mains timer, permitting unattended recording or automatic playback.
Three tape-selection positions corresponded with the Type I, Type II and Type III Elcaset formulations. The selected tape type determined the appropriate recording bias and equalisation requirements, with front-panel indicators showing the active setting. Internal adjustments were provided for bias, recording level, recording equalisation and playback equalisation. Twin illuminated VU meters displayed the left and right recording or playback levels. The meters were supported by adjustable internal calibration circuits, allowing their indications to be aligned with the deck’s specified output level. Separate microphone and line controls provided recording-level adjustment, while the output control governed playback level.
The microphone section included separate left and right inputs, with the left socket also serving as a mono input. A separate line-level control handled signals received through the rear line inputs. The front-panel headphone socket allowed direct monitoring, while the monitor selector provided switching between the incoming source and the signal reproduced from tape. The input and MPX filter selector allowed the appropriate recording input and filter condition to be chosen. The multiplex filter was intended for recording FM stereo broadcasts by reducing interference from the transmitted pilot signal. Record muting allowed silent intervals to be inserted while making a recording without stopping the transport.
Dolby noise reduction was built into the TEAC AL-700. The specified signal-to-noise ratio in playback was 50dB with Dolby switched out and 53dB with Dolby engaged. Overall record and playback signal-to-noise figures were 47dB without Dolby and 52dB with Dolby when measured using the specified Type II test tape. The TEAC AL-700 was specified for a playback wow and flutter figure of 0.04% weighted RMS and an overall record and playback figure of 0.06% weighted RMS. Fast winding an LC-60 cartridge required approximately 80 seconds. The end-stop mechanism operated approximately eight seconds after the transparent leader was detected during play and approximately 1.5 seconds after detection during fast winding.
Erase efficiency was rated at 65dB or greater at 1kHz, while record-mute erase efficiency was specified at 60dB or greater at 1kHz. Crosstalk was rated at 40dB or greater at 125Hz, and stereo channel separation was 46dB or greater at 1kHz. Overall total harmonic distortion was specified at 1.5%. The deck provided microphone and line inputs together with line and headphone outputs. The specified microphone input level was 0.775mV into 10kΩ, with a minimum sensitivity of 0.244mV. The line input was specified at 194mV into 50kΩ, with a minimum sensitivity of 61.5mV. The line output was rated at 435mV into 50kΩ, reaching a maximum of 869mV, while the headphone output was rated at 92mV into 8Ω.
Different mains-voltage versions of the TEAC AL-700 were produced for international markets. The United States and Canadian model operated from 117V AC at 60Hz, while export versions supported 100V, 117V, 220V or 240V supplies at 50Hz or 60Hz. European models operated from 220V at 50Hz, and models for the United Kingdom and Australia used 240V at 50Hz. Power consumption was 55W.
The internal construction was arranged around separate printed circuit boards for the control, oscillator, recording amplifier, output amplifier, Dolby encoder and decoder, playback amplifier, microphone amplifier, power supply and transport-control sections. The use of modular circuit boards and clearly identified adjustment points supported servicing and calibration, although the mechanical and electronic complexity required specialist maintenance. With its wood side panels, brushed-metal front panel, large VU meters and extensive control layout, the TEAC AL-700 reflected TEAC’s recorder design language of the late 1970s. Its 20kg construction housed a substantial three-motor transport, separate recording heads, independent electronics and a rigid chassis designed around the larger Elcaset cartridge.
The TEAC AL-700 represented TEAC’s most ambitious production recorder for the Elcaset format. Its combination of a three-head signal path, three-motor closed-loop dual-capstan transport, off-tape monitoring, Dolby noise reduction and comprehensive recording controls placed it between high-grade cassette decks and domestic open-reel recorders. Although Elcaset achieved only limited commercial adoption, the TEAC AL-700 remains a technically significant example of the effort to combine open-reel recording principles with cartridge-based operation.
Features
- Four-track, two-channel stereo Elcaset recording system
- Separate erase, record and playback heads
- Three-motor transport
- Frequency-generator servo-controlled DC capstan motor
- Two independent coreless DC reel motors
- Closed-loop dual-capstan tape transport
- Twin-belt capstan drive
- Air-damped flywheel mechanism
- Self-aligning pinch rollers
- Semi-fixed head mounting system
- Off-tape monitoring during recording
- Compatibility with LC-60 and LC-90 Elcaset cartridges
- Support for Type I, Type II and Type III Elcaset tape
- Dolby noise reduction
- Twin illuminated VU meters
- Record-mute function
- Photoelectric tape-end detection
- Automatic end-stop operation
- Memory stop and play functions
- Timer-controlled recording and playback
- Switchable MPX filter
- Separate microphone, line and output level controls
- Separate left and right microphone inputs
- Front-panel headphone output
- Source and tape monitoring
- Large logic-controlled transport keys
- Wooden side panels