Introduced in 1998, the Marantz PMD520 was a professional three-head dual-well cassette deck developed for recording, duplication, continuous programme capture and multi-machine installations. Unlike conventional domestic double cassette decks, the Marantz PMD520 contained two fully independent recording and playback systems, each with its own stationary three-head mechanism, controls, metering, tape counter, calibration system and audio connections. The two wells could operate separately, work together within a single machine or be connected with additional PMD520 units for extended recording and cassette duplication systems.
Each cassette well could record or reproduce a different source independently. Two separate programmes could be recorded simultaneously, two different tapes could be played at the same time, or one well could reproduce a cassette while the other recorded an unrelated source. Separate line inputs and outputs were provided for Deck A and Deck B, while a rear-panel input selector allowed both wells to receive the signal connected to Deck A when parallel recording or duplication was required.
The Marantz PMD520 used stationary three-head mechanisms comprising separate record, playback and erase heads. The hard Permalloy record and playback heads allowed the recorded signal to be monitored directly from the tape during recording, while dual-gap ferrite erase heads removed the previous recording. The approximate head life was specified at 1,000 hours.
Direct cassette insertion replaced the conventional hinged doors fitted to many cassette decks. Each cassette was inserted directly into its exposed holder with the tape opening facing downwards. Removable dust covers were supplied to protect the mechanisms when the deck was not in use.
The cassette mechanisms were designed as individually removable assemblies. One complete transport could be removed for servicing while the second mechanism remained installed and available for operation. This modular arrangement reduced the disruption caused by maintenance in professional environments where continued access to at least one cassette well could be important.
Each mechanism used a DC servo-controlled capstan motor and a separate DC reel motor. The transport controls included stop, play, fast forward, rewind, record and record mute. Large buttons with inset indicators showed the selected operating condition, and the transport could enter cue or review operation from playback before changing to full fast-wind speed.
The Marantz PMD520 supported normal, high-bias and metal cassette formulations. An automatic tape selector detected the identification holes in the cassette shell and selected the corresponding bias and equalisation settings. Normal tape used 120µs equalisation with low bias, while high and metal tapes used 70µs equalisation with the appropriate high or metal bias setting.
A microprocessor-controlled Auto Bias and EQ system adjusted the recording characteristics for the tape loaded into each mechanism. The system calibrated bias, recording gain, medium-frequency gain, high-frequency gain and high-frequency peak response. Adjustment values were selected from 64 steps through a six-bit digital-to-analogue converter, with each step applied at intervals of 100 milliseconds.
Bias calibration used a 6.3kHz test signal. The system located the tape’s peak output point and then selected a bias level 5dB below the peak for normal and high-bias tape, or 2.5dB below the peak for metal tape. This allowed the calibration to account for the maximum output level and third-order distortion characteristics of the tape and recording head.
Recording gain was adjusted with an internally generated 400Hz signal, while a 3kHz signal established the medium-frequency gain and a 12.5kHz signal set the high-frequency gain. The calibration data was stored separately for normal, high-bias and metal tape and retained in EEPROM after the Marantz PMD520 was switched off. A Bias Reset control allowed the user to alternate between the calibrated values and the standard factory settings.
The automatic calibration routine required a recordable cassette with intact protection tabs, the mechanism in stop and the tape speed set to normal. The display showed the calibration process and counted down until completion. The tape was then rewound automatically to the point at which calibration began. Error messages identified tape-end, oscillator, bias-setting, recording equalisation or total-adjustment failures.
Each cassette well included independent fluorescent bar-graph level meters with peak indication. These displayed stereo recording and playback levels from minus infinity to +6dB. Separate linear tape counters showed the approximate tape position in minutes and seconds, with selectable reference settings for tapes ranging from C-10 to C-120. Removing a cassette and inserting another automatically reset the corresponding counter to 00:00.
The record controls included individual recording-level and recessed balance adjustments for each well. Record mute inserted three seconds of silence during recording, while separate monitor buttons selected either the input source or the signal reproduced directly from tape. The monitor indicator illuminated when tape monitoring was active.
Dolby B and Dolby C noise reduction were independently selectable for each cassette well. Dolby B provided a specified signal-to-noise improvement of 8dB under CCIR/ARM weighting, while Dolby C provided an improvement of 17dB. Dolby HX Pro headroom extension operated during recording by monitoring the effective bias and reducing the deck’s bias level when necessary. Because Dolby HX Pro required no playback decoding, recordings made with it retained their benefits when reproduced on another cassette deck.
The Marantz PMD520 could record and play at the normal cassette speed of 4.75cm/s or operate at 9.5cm/s for high-speed duplication. Dolby noise reduction was disabled automatically during high-speed operation because its dynamic processing characteristics were intended for real-time recording and playback. A recessed fine-speed adjustment provided a range of ±3% for each cassette well.
Parallel recording allowed the same programme connected to Deck A to be recorded simultaneously by both cassette wells. Pressing the A+B Record control placed both mechanisms into record-pause, allowing their levels to be adjusted before recording commenced. Both transports could then be started, paused or stopped together.
Continuous recording transferred operation automatically from one cassette well to the other. Using two C-90 cassettes, the Marantz PMD520 could provide approximately 90 minutes of uninterrupted recording or playback before further intervention. The completed cassette could also be rewound automatically when the Auto Rewind function was enabled.
Overlap series recording was provided for applications in which no part of a programme could be lost during a cassette change. Rather than waiting for the first tape to finish, the second well began recording approximately three minutes before the current tape reached its end. This created an overlapping section on both cassettes and ensured continuous coverage of conferences, meetings, broadcasts and other extended events.
The overlap system could alternate repeatedly between the two mechanisms when the continuous loop mode and automatic rewind were used. The operator could remove or reverse the completed cassette and prepare it before the second cassette approached its end. The three-minute common section provided time for the transition without creating a gap in the recorded programme.
Continuous and overlap recording could be extended across multiple Marantz PMD520 units through the rear-panel extension connections. When the second well of the first machine reached the end of its tape, it could trigger the first well of the next connected Marantz PMD520. Additional units could be linked in sequence for logging and other long-duration recording applications.
The Marantz PMD520 also supported duplication across large installations. Its Deck A loop-through output passed the input signal to another machine without requiring an external distribution amplifier for each connection. The WRC220 wired remote could control up to 100 interconnected Marantz PMD520 units for normal-speed or high-speed duplication.
During normal-speed duplication, Dolby noise reduction could be selected as required. When the Marantz PMD520 was used as the master and slave recording levels were set to their centre positions, the deck was designed to maintain the copied level within 1dB of the source tape. High-speed duplication operated at twice normal speed and automatically disabled Dolby processing during the transfer.
The rear panel included independent line inputs and outputs for both cassette wells. Deck A also provided a loop-through output for feeding further recorders. An input selector allowed the wells to receive separate sources or share the signal connected to Deck A. Shorting plugs were fitted to the Deck B input sockets when no direct source was connected, reducing the possibility of crosstalk when one mechanism was recording while the other was reproducing a tape.
An MPX filter could be switched into the recording path when capturing FM stereo broadcasts. The filter reduced interference from the transmitted pilot signal, which could otherwise affect recording or noise-reduction operation.
Remote facilities included Marantz RC-5 input and output connections, extension connectors for cascade operation and a 25-pin Control I/O port. The RC-5 output allowed commands to be passed to additional compatible equipment, while the extension connection coordinated continuous recording and playback between multiple PMD520 decks.
The 25-pin Control I/O connector provided contact-closure inputs for rewind, fast forward, play, stop, record and record mute on both mechanisms. It also accepted commands for parallel recording, normal and high tape speed, automatic rewind, tape-time selection, counter reset and automatic bias adjustment. Outputs indicated high-speed operation and A+B recording status, allowing the PMD520 to be integrated with custom control systems.
Optional remote controllers included the Superscope WRC220 wired remote and RC5PMD infrared remote. The Marantz PMD520 was also compatible with control systems using its RC-5 command structure, including installations based around AMX or Crestron equipment. Quick Music Search was available through remote control and could locate up to 15 programme divisions by detecting blank spaces between recorded selections.
Timer recording and playback were supported independently for both wells. With the timer selector set to record or play, the chosen mechanism began operating automatically when power was applied by an external timer. The function could be used for unattended recording or scheduled programme playback.
A tape-stop alarm generated an audible warning when either well reached the end of a cassette. Automatic rewind could be enabled for both transports, causing each mechanism to rewind when the end of its tape was detected. These functions reduced the need for constant observation during extended recording or playback.
The headphone section included an adjustable level control and a selector for monitoring Deck A, Deck B or a mix of both. This allowed the operator to check either mechanism independently or monitor both cassette wells from a single headphone output.
An optional XLR520PMD balanced connection kit allowed the Marantz PMD520 to be integrated with professional audio systems using balanced XLR wiring. In its standard form, the deck used unbalanced line connections. The detachable grounded mains lead simplified installation and replacement within permanent rack systems.
The Marantz PMD520 was built into a one-piece 3U rackmount chassis measuring 132mm high, 483mm wide and 340mm deep. At 7kg, it provided two fully independent cassette recorders, their associated control systems and the interfaces required for duplication, cascade recording and remote operation within a single rack-mounted unit.
The Marantz PMD520 represented one of the most comprehensive professional double cassette decks produced near the end of the cassette era. Rather than treating its second transport primarily as a dubbing convenience, it provided two independent three-head recorders capable of separate, parallel, continuous and overlapping operation. Its modular transports, automatic tape calibration, extensive remote interfaces and multi-machine expansion facilities made it suitable for duplication, logging, conference recording, institutional audio systems and other applications requiring reliable cassette-based recording.
Features
- Two fully independent cassette recording and playback systems
- Two stationary three-head mechanisms
- Separate hard Permalloy record and playback heads
- Dual-gap ferrite erase heads
- Direct cassette insertion and removal
- Removable cassette mechanisms for servicing
- Independent recording and playback from both wells
- Off-tape monitoring during recording
- Normal, high-bias and metal tape compatibility
- Automatic tape-type detection
- Microprocessor-controlled automatic bias and equalisation
- Automatic adjustment of bias, recording gain and frequency response
- Calibration memory retained in EEPROM
- Independent fluorescent stereo bar-graph meters
- Independent linear tape-time counters
- Selectable tape-length reference settings
- Automatic counter reset when changing cassettes
- Dolby B and Dolby C noise reduction
- Dolby HX Pro headroom extension
- Normal-speed recording and playback
- Double-speed duplication
- Independent ±3% fine-speed controls
- Simultaneous parallel recording
- Continuous recording and playback
- Three-minute overlap series recording
- Multi-machine cascade recording and playback
- Loop-through output for duplication systems
- Automatic rewind
- Record-mute function
- Tape-stop alarm
- Timer-controlled recording and playback
- Switchable MPX filter
- Independent recording-level and balance controls
- Selectable headphone monitoring of Deck A, Deck B or both
- RC-5 remote input and output
- Extension connections for cascade operation
- 25-pin contact-closure Control I/O port
- Remote Quick Music Search for up to 15 selections
- Optional Superscope WRC220 wired remote controller
- Optional RC5PMD infrared remote controller
- Optional XLR520PMD balanced XLR connection kit
- Removable mechanism dust covers
- Detachable grounded mains lead
- One-piece 3U rackmount chassis