Released in 1978, the Sony EL-7 was a high-fidelity stereo ELCASET deck designed to combine the operating convenience of a cassette machine with performance closer to an open-reel recorder. ELCASET used a substantially larger cartridge than the compact cassette and contained 6.3mm tape, approximately twice the width of cassette tape. It ran at 9.5cm/s, also twice the compact cassette speed, providing greater recorded tape area, wider frequency response, improved signal stability and reduced susceptibility to mistracking between the recording and playback heads.
The ELCASET cartridge was designed so that the tape itself, rather than the cartridge shell, was guided by the recorder’s transport. When loaded into the Sony EL-7, the tape was drawn from the cartridge and passed across fixed heads, capstans and guides in a manner closer to an open-reel recorder. This reduced the transport’s dependence on the mechanical precision of the cartridge shell and allowed the deck to maintain more consistent tape movement and head contact.
Sony played a major role in the development of the ELCASET format, applying its experience in tape recording and blank-tape manufacture to the system. The Sony EL-7 was the company’s more advanced ELCASET deck and included a three-head configuration, closed-loop dual-capstan transport, three-motor mechanism, logic-controlled solenoid operation, Dolby noise reduction and extensive recording and monitoring facilities.
The Sony EL-7 employed separate recording, playback and erase heads. This true three-head arrangement allowed the recording and playback heads to be independently designed for their respective functions and enabled immediate monitoring of the signal being recorded. By switching between source and tape, the operator could compare the incoming programme with the signal reproduced directly from the tape while recording remained in progress.
Each of the three heads used Sony’s ferrite-and-ferrite construction. Ferrite offered greater magnetic permeability at high frequencies than conventional permalloy and provided a hard, wear-resistant surface that supported longer service life and stable head-gap alignment. Its characteristics also contributed to broad frequency response, close tape contact and accurate stereo imaging.
The playback and recording heads were direct-coupled to their corresponding amplifiers. This arrangement reduced the number of intermediate components in the signal path and formed part of the Sony EL-7’s approach to maintaining stable recording and reproduction characteristics across the audio band. A closed-loop dual-capstan transport was used to maintain controlled tape tension across the head assembly. Two capstans and two pinch rollers were positioned on opposite sides of the heads, creating an isolated section of tape between them. The capstans operated at slightly different effective speeds so that the tape remained under consistent tension as it passed across the recording and playback heads.
This closed-loop arrangement reduced the effect of disturbances originating from the supply and take-up reels. Changes in reel tension were substantially isolated from the tape section passing over the heads, helping to limit tape vibration, modulation noise and irregular movement. Stable tape-to-head contact was therefore maintained during recording and playback. The Sony EL-7 used three separate motors. One motor drove the capstan system, while two additional motors handled reel rotation during normal operation and rapid winding. Dividing these functions between individual motors simplified the mechanical load placed on each drive section and allowed the reel and capstan systems to operate independently.
The capstan was driven by a frequency-generator servo-controlled DC motor. Electronic speed regulation maintained accurate tape movement, while the closed-loop dual-capstan arrangement provided the mechanical stability required for the ELCASET format. The deck achieved a specified wow and flutter figure of 0.04% weighted RMS. Fast winding was also a major part of the transport design. The Sony EL-7 could wind an LC-60 ELCASET tape in approximately 60 seconds. Logic-controlled transport operation allowed direct selection between operating modes without requiring the machine to pass through stop first.
The principal transport functions were controlled through solenoid-operated pushbuttons. These feather-touch controls operated the tape mechanism through logic circuitry rather than direct mechanical linkages. Punch-in recording was also possible through the logic-controlled transport, allowing the deck to enter record mode during operation. A photoelectric all-mode automatic shut-off system monitored the transparent leaders fitted to ELCASET tapes. When the leader reached the sensing point, the deck stopped the transport automatically. The system operated across the principal transport modes and reduced mechanical stress on the tape and recorder.
The Sony EL-7 included an air-damped ELCASET compartment for controlled loading and smooth ejection. The mechanism presented the large cartridge through a front-loading compartment and lowered it into the transport assembly, where the tape could be drawn out and positioned against the heads and guides. Three tape formulations were supported through dedicated bias and equalisation settings. These covered standard ferric tape, ferri-chrome tape and chromium dioxide tape. The operator selected the appropriate bias and equalisation position for the loaded formulation, allowing the recording electronics to be matched to the tape.
The deck was compatible with Sony ELCASET tapes in LC-60 and LC-90 lengths, providing respective nominal playing times of 60 and 90 minutes. The cartridge incorporated coded sensing features, transparent leaders, reversible erase-protection controls and a large tape-viewing window. Dolby noise reduction was fitted to improve signal-to-noise performance during recording and playback. The deck also included a built-in 400Hz test oscillator intended for Dolby calibration when recording material away from broadcast sources. This allowed recording levels to be established consistently before programme material was recorded.
A switchable FM multiplex filter was provided for recording stereo FM broadcasts with Dolby noise reduction. The filter removed the FM pilot and subcarrier components that could interfere with the correct operation of the Dolby circuitry. The Sony EL-7 included separate microphone and line recording controls for each channel, together with a master recording fader. Microphone and line sources could be mixed, giving the deck greater flexibility for live recording and programme assembly. A three-position microphone attenuator provided settings of 0dB, -15dB and -30dB, allowing higher-level microphone signals to be accommodated without overloading the input stage.
A front-panel line input provided quick connection of a temporary source without requiring access to the rear connections. Separate output controls were supplied for the line and headphone circuits, allowing monitoring level and system output level to be adjusted independently. Two large calibrated VU meters displayed either the source signal or the signal reproduced from tape. Combined with the separate source and tape monitor selector, these meters allowed the operator to compare input and recorded levels while a recording was being made.
A three-digit tape counter incorporated memory stop and memory play functions. Memory stop allowed the transport to return to and halt at a predetermined counter position, while memory play could return the tape to the selected point and automatically begin playback. These functions simplified repeated access to specific sections of a recording. The Sony EL-7 also supported timer-controlled recording and playback through its standby facility. When connected to a suitable external timer, the deck could begin operation automatically at a selected time. A full-function remote-control facility was available through the optional Sony RM-30 remote unit.
Two rear-panel AC convenience outlets were included, with one switched and one unswitched. These allowed compatible ancillary equipment to be powered alongside the recorder, subject to the electrical requirements of the system. The Sony EL-7 represented the most fully equipped ELCASET recorder in Sony’s range. Its combination of three separate heads, three motors, a closed-loop dual-capstan transport, logic-controlled operation, direct tape monitoring, comprehensive input mixing and remote-control capability placed it at the upper end of the format’s domestic recording machines.
Although ELCASET did not achieve long-term commercial adoption, the Sony EL-7 remains an important example of the effort to combine open-reel tape performance with cartridge-based convenience. Its transport design, head system and recording controls reflected the level of engineering applied to the format during its brief period of production.
Features
- Three-head ELCASET recording and playback system
- Separate recording, playback and erase heads
- Ferrite-and-ferrite head construction
- Three-motor tape transport
- Closed-loop dual-capstan drive
- Frequency-generator servo-controlled DC capstan motor
- Logic-controlled solenoid transport operation
- Direct switching between transport modes
- Photoelectric all-mode automatic shut-off
- Fast winding of an LC-60 tape in approximately 60 seconds
- Standard, ferri-chrome and chromium dioxide tape settings
- Direct-coupled recording and playback amplifiers
- Dolby noise reduction
- Built-in 400Hz Dolby calibration oscillator
- Switchable FM multiplex filter
- Separate microphone and line recording controls for each channel
- Microphone and line mixing
- Master recording fader
- Three-position microphone attenuator
- Separate headphone and line output-level controls
- Quick-access front-panel line input
- Large calibrated VU meters
- Source and tape monitoring
- Three-digit tape counter
- Memory stop and memory play
- Timer-controlled recording and playback standby
- Logic-controlled punch-in recording
- Air-damped ELCASET loading compartment
- Optional RM-30 full-function remote control
- Two AC convenience outlets