The Marantz SD6000 was a two-speed stereo cassette deck introduced around 1980 as part of Marantz’s late-1970s SD series. Combining a two-head recording system, dual DC servo motors, support for four principal tape formulations and operation at both standard and double cassette speeds, the Marantz SD6000 was designed to provide greater flexibility than a conventional domestic cassette recorder.
The most distinctive feature of the Marantz SD6000 was its ability to operate at tape speeds of 4.76cm/s and 9.5cm/s. The standard 4.76cm/s setting maintained compatibility with ordinary compact cassette recordings, while the 9.5cm/s setting moved the tape at twice the normal speed. This higher-speed mode used twice as much tape for a given recording time but allowed the cassette format to operate with an extended frequency response and reduced susceptibility to speed-related performance limitations.
A large front-panel speed selector allowed the operator to choose between the two operating speeds. Recordings made at 9.5cm/s required playback on a deck equipped with the same double-speed facility, while recordings made at 4.76cm/s remained compatible with conventional cassette equipment.
The Marantz SD6000 used a two-head configuration consisting of a combined record and playback head together with a separate erase head. Unlike a three-head deck, it could not reproduce the recorded tape immediately after the record head during recording. Monitoring was therefore based on the incoming source signal rather than direct off-tape reproduction.
Tape movement was handled by two DC servo motors. Separating the principal transport duties between two motors reduced dependence on a single motor and allowed more controlled handling of the capstan and reel functions. The transport provided the conventional recording, playback, fast-forward, rewind, pause and stop operations expected of a full-sized cassette deck.
The Marantz SD6000 could record and reproduce Type I ferric, FeCr, CrO₂ and Metal tapes. Front-panel tape selectors configured the recording and playback circuits for the selected formulation. Metal tape compatibility was particularly significant when the SD6000 appeared, as Metal formulations had only recently entered the domestic cassette market.
A manually adjustable bias control allowed the recording bias to be refined for the cassette being used. This provided a degree of optimisation beyond the main tape-type selector, accommodating variations between tape brands and formulations within the same nominal category.
Dolby B noise reduction was included for recording and playback. When used with suitably encoded recordings, Dolby B reduced the prominence of tape hiss, particularly at higher frequencies. The deck’s published signal-to-noise ratio was 71dB with Dolby B engaged.
Recording levels were monitored through two large illuminated analogue meters, one for each stereo channel. The meters allowed the left and right recording levels to be observed independently, helping the operator avoid excessive levels that could overload the tape while still recording strongly enough to minimise audible background noise.
Separate left and right recording-level controls were provided, allowing the stereo balance to be adjusted before or during recording. A master recording-level control enabled both channels to be altered together after their relative balance had been established.
The Marantz SD6000 included front-mounted microphone connections for direct recording, together with line-level inputs for connection to an amplifier, receiver or other audio source. Its specified input sensitivity was 70mV for the line input and 0.25mV for the microphone input. The specified line output level was 0.65V.
A front-panel headphone connection allowed recordings and playback to be monitored without using an external loudspeaker system. The output-level control provided adjustment of the monitoring level without altering the recorded signal.
The transport section incorporated a mechanical three-digit tape counter. A memory-stop function could be used with the counter to help return the tape to a selected position, providing a practical method of locating the beginning of a recording or another marked point on the cassette.
The Marantz SD6000’s electronic design used nine integrated circuits, 93 transistors, 61 diodes and seven light-emitting diodes. These devices supported the audio, motor-control, metering, switching and indication circuits within the machine.
The front panel followed the visual style of Marantz components from the period, with a brushed-metal finish, dark cassette compartment, illuminated analogue meters and substantial rotary controls. The operating sections were arranged across the full width of the deck, separating the tape transport, metering, recording adjustments and output controls into clearly defined areas.
Published specifications gave the Marantz SD6000 a frequency response of 30Hz to 22kHz with Metal tape, a signal-to-noise ratio of 71dB with Dolby B and wow and flutter of 0.03 per cent. These figures reflected the performance available from its dual-speed transport, although the applicable tape speed and measurement conditions should be considered when comparing the deck with conventional single-speed models.
The Marantz SD6000 occupied an unusual position in the cassette market. It retained the familiar compact cassette format while offering a second operating speed more commonly associated with specialised or semi-professional cassette machines. Its combination of double-speed recording, Metal tape compatibility, two-motor transport and extensive manual recording controls distinguished it from more conventional Marantz cassette decks of the period.
Features
- Two-speed operation at 4.76cm/s and 9.5cm/s
- Two-head recording and playback system
- Separate erase head
- Two DC servo motors
- Support for Type I, FeCr, CrO₂ and Metal tapes
- Dolby B noise reduction
- Manual tape-type selection
- Adjustable recording bias
- Separate left and right recording-level controls
- Master recording-level adjustment
- Illuminated analogue recording-level meters
- Mechanical three-digit tape counter
- Memory-stop function
- Front-panel microphone inputs
- Front-panel headphone connection
- Adjustable output level