The Roland MKS-50 was a polyphonic synthesiser module designed to fit into a single rack unit, offering the same sound circuitry and functions as the Alpha-JUNO synthesiser. This compact package allowed musicians to integrate the distinctive sound of the Alpha-JUNO into rack-mounted setups without the footprint of a full-sized keyboard instrument.
The unit operated as a six-voice polyphonic synthesiser, capable of storing up to 128 programmable sounds, known as Tones. The sound generation relied on a Digital Controlled Oscillator (DCO) that incorporated a newly developed LSI to produce fourteen different basic waveforms. This capability enabled the creation of sounds with a variety and quality that extended beyond the scope of ordinary analogue synthesisers.
The envelope generator served as a critical component for sound synthesis in the Roland MKS-50, featuring a seven-parameter design. Unlike conventional ADSR envelope generators, this system could create more complex envelope curves, allowing for more expressive and impressive sonic results. The parameters included four time settings and three level settings, providing detailed control over the evolution of the sound. Additionally, the Roland MKS-50 featured Roland’s unique Chorus circuitry, which was used to broaden and thicken the synthesised sounds. The Chorus function could be switched on or off, and its rate was programmable, adding depth to the output.
Sound editing and parameter confirmation were managed via the controls on the front panel, which included an easy-to-read display. Users could create sounds by adjusting various parameters and then store them in the unit’s internal memory. Each stored Tone could be accompanied by a name of up to ten characters, facilitating easier identification and recall.
For more advanced programming, an optional PG-300 programmer could be connected to the unit to facilitate the powers of sound synthesis. The front panel also included buttons for Tune/MIDI, Name, Data Transfer, Write, Patch, Tone, Number, Parameter, and Value, along with a Power switch and a MIDI LED indicator.
The Roland MKS-50 offered extensive programmability for the DCO, including range settings from 32′ to 4′, LFO modulation depth, and envelope modulation depth with modes for Normal, Inverted, and Dynamics-sensitive operation. Aftertouch sensitivity, bend range, and pulse-width modulation depth and rate were also adjustable.
The oscillator section allowed for the selection of pulse, sawtooth, and sub-oscillator waveforms, with independent level controls for the sub-oscillator and noise. The filter section included a high-pass filter and a Voltage Controlled Filter (VCF) with cutoff frequency, resonance, and modulation depth controls. The VCF also supported envelope and LFO modulation, keyboard follow, and aftertouch sensitivity.
The Voltage Controlled Amplifier (VCA) section provided level control and envelope modes, including ENV, Gate, and variants with Dynamics. Aftertouch sensitivity for the VCA was also programmable. The Low Frequency Oscillator (LFO) had adjustable rate and delay time. These parameters, combined with the seven-parameter envelope generator, allowed for precise sculpting of the sound’s timbre and dynamics. The unit’s internal memory held 128 Tones, each representing a complete set of these synthesis parameters.
Beyond individual Tones, the Roland MKS-50 could store 128 Patches. A Patch included a variety of function settings in addition to tone assignments. These settings included volume, modulation sensitivity, portamento on/off and time, key shift, detune, and key range limits for both low and high notes. MIDI-specific settings such as aftertouch, bender, exclusive, hold, modulation, volume, and portamento reception could also be stored within a Patch. The Assign Mode could be set to Poly, Mono, or Chord Memory, determining how the voices were triggered and controlled.
The Chord Memory function allowed the Roland MKS-50 to store chord patterns that could be played by pressing a single key. Up to sixteen such chord patterns could be stored, with each pattern consisting of up to six notes assigned within the range of two octaves below and above the note C4. These chord patterns could be created using the front panel controls or by using a MIDI keyboard connected to the unit. This feature provided a convenient way to trigger complex harmonic structures with a single key press, useful for accompaniment or specific musical effects.
A built-in tape interface allowed the data for tones, patches, and chord patterns to be stored on cassette tapes, providing a method for backup and transfer of user data. The rear panel included jacks for the Tape Interface (Save/Load), as well as MIDI In, Out, and Thru connections. Audio outputs were available in mono and stereo configurations, and a stereo headphone output was provided for private monitoring. The unit was designed for EIA-1U rack mounting, with dimensions of 44mm in height, 480mm in width, and 290mm in depth.
MIDI functionality was a central aspect of the Roland MKS-50’s operation. The MIDI channel was assignable to any one of sixteen channels. The receive mode could be set to Poly or Mono, with Omni on or off. In Omni off/Mono mode, each of the six voices was controlled by MIDI messages transmitted on six successive MIDI channels, starting with the assigned channel.
This configuration allowed for expressive control using MIDI-compatible guitar controllers, such as a normal electric guitar with Roland’s GK-1 Synthesiser Driver and GM-70 GR-MIDI Converter, or Roland’s G-series guitar controller with the GM-70. Guitar techniques like bending, vibrato, and slurring could be used to control the synthesiser sounds.
The Roland MKS-50 received all MIDI note messages from 0 to 127, producing sounds within the note range corresponding to MIDI note numbers 12 to 108. It also received MIDI velocity messages. The reception of MIDI bender messages was selectable, with bending achieved at a nine-bit resolution and a chromatically adjustable range within one octave.
The unit could receive specific MIDI control change messages, including modulation (number 1), portamento time (number 5), volume (number 7), hold (number 64), and portamento switch (number 65). The reception of these individual control change messages and channel aftertouch messages could be enabled or disabled. The bend range could also be chromatically adjusted using MIDI registered parameter messages, with a range of 0 to 24.
The Roland MKS-50 received MIDI program change messages from 0 to 127, which could be used to recall stored patches. The reception of program change messages could be disabled. System Exclusive messages could be received and transmitted, allowing for data transfer between two Roland MKS-50 units, including all stored tones, patches, and chord patterns.
Tone data could also be transferred when connected to a Roland Alpha-JUNO or Synth Plus 80. When the MIDI Exclusive function in the Patch settings was turned on, the Roland MKS-50 transmitted system exclusive messages for the patch, allowing compatible sequencers, such as Roland’s MC-500, to change the patch functions using stored data. The unit also received All Note Off and Active Sensing messages.
Features
- Six-voice polyphonic synthesis with the same sound circuitry and functions as the Alpha-JUNO synthesiser.
- DCO with fourteen basic waveforms, including pulse, sawtooth and sub-oscillator waveform selections.
- Programmable DCO modulation, aftertouch sensitivity, bend range, sub-oscillator level, noise level and pulse-width modulation.
- High-pass filter and VCF controls for cutoff, resonance, envelope and LFO modulation, keyboard follow and aftertouch sensitivity.
- VCA envelope and gate modes, including dynamics-sensitive operation.
- Seven-parameter envelope generator, with four time and three level parameters.
- Roland Chorus circuitry with programmable on/off and rate settings.
- Front-panel sound editing and optional PG-300 programmer support.
- Tone storage with names of up to ten characters.
- Patch storage for tone assignments, volume, modulation sensitivity, portamento, key shift, detune, key ranges and MIDI receive settings.