GMS-790 Quad Quantizer

Multi-function MIDI Tool does CV Quantization, CV to MIDI Conversion and CV Recording

The GMS-790 Quad Quantizer module offers the ability to quantize continuous analog voltage values into discrete note voltage values either chromatically into 12 discrete voltages or based on a scale such as C# minor emitting discrete voltages and gates for the notes in that scale. Up to four quantizers are available that can all be set to one scale or used independently. Preprogrammed scales are available as well as 8 user definable scales. The module can also be used as a CV to MIDI converter with note commands output as 5 pin DIN MIDI or USB MIDI. Analog and MIDI transpose inputs are provided to offset the converted note values by the input value. Through the panel USB 2.0 connector, the module can support USB Device connections to a remote computer or the module can provide USB Host support for other USB Devices such as keyboard controllers or sequencers. 


Each quantizer channel can be set to an available quantization scale or a previously stored user scale can be loaded. The default scales include:

  • Major
  • Minor
  • Minor Pentatonic
  • Dorian
  • Major Third
  • Minor Third
  • Whole Tone
  • Chromatic

Nonvolatile storage for eight user defined scales is also included.

The key in which quantization occurs can be preselected for each channel. This limits the quantized notes to only the notes in the scale of the selected key.

Multiple quantizers can be configured simultaneously by selecting “Quant” from the four function keys above the scale keys area, enabling the desired quantizers by selecting their numbers from the scale keys (indicated by a flashing gate lamp), and selecting the desired settings from the OLED display. The settings can be saved as a user default that will be loaded the next time the quantizer is powered on or as a set of user settings saved in nonvolatile memory.

A note input can be quantized and used to select up to four notes of a chord value if a key is set. The voltage value for each note of the chord will be output on a separate output channel along with a gate signal on each channel for the duration of the note. The generated note values can also be routed to either the DIN MIDI or USB MIDI output.


The quantizer module can output results of quantized input values as MIDI note commands. These quantized values can be sent to specific MIDI channels depending on routing configurations. A single quantized input voltage can be converted to a MIDI note command and sent to a preselected MIDI channel or multiple quantized voltages from several input channels can be combined and sent on one MIDI output channel to be used to play a chord on a polyphonic synthesizer.

The module will output the MIDI note information on either the 5 pin DIN MIDI output connector or output as USB MIDI on the USB connector.

The USB connector supports USB 2.0 and can be configured as a USB Device or a USB Host. In the Host mode, the module can be connected directly to external modules, synthesizers, or sound generators without the need for an intervening computer to host the external device. In USB Host mode, USB hub support is provided and connected devices will be enumerated automatically and presented in the USB routing menu. Device targets can be routed with USB streams coming from specific sources so multiple output devices do not have to receive the same input stream.


Each quantizer channel can be configured as a triggerable sample and hold. When a trigger input pulse occurs, the current value of the analog input on the channel will be transferred to the analog output and held at that value until a new trigger input is received.

Analog and DIN MIDI transpose inputs are provided to allow the current analog output values to be transposed to a new basis depending on the value of the analog input voltage or MIDI note received. If the analog voltage input is used, it can be quantized to a scale value before it is added to the output voltage values.


Technical Specifications

Mixer Section

Clock 0-5V
Reset 0-5V

Typical Input Impedance
100K Ohms

CV 0-2.5V; 0-5V; 0-10V
Internal jumper selection
Gate 0-5V

Typical Output Impedance
1K Ohms (short circuit protection)

Module Power
+15 Volts 25 mA.
-15 Volts 25 mA.

Module Size
Panel height - 8.75 inches (222 mm)
Panel width - 2.125 inches (54 mm)
Depth (behind panel) 2.1 inches (53 mm)



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