modular analog synthesizer for electronic music
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 Q175  MIDI Interface Aid

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The Q175 MIDI Interface Aid module operates in conjunction with the Q174 MIDI Interface module to provide additional MIDI connectivity features, an Arpeggiator and Portamento (glide between notes).

The Q175 can not operate stand-alone, it must be connected to the Q174 MIDI Interface module.
Connectors from the Q175 module plug into the Q174's circuit board.

A MIDI Thru output and an additional MIDI input gives the user many options to connect multiple external devices to the Q174/Q175 module pair. Multiple controllers producing Note On and Note Off messages along with Pitch Bend messages can be combined to control a single channel of Pitch and Gate outputs, two channels using Mode 2, or CC messages using Mode 3.

The Arpeggiator automatically cycles through notes that are held down. The operator has complete control over the cycling rate using the manual speed control, or it can be driven from an external clock to synchronize with sequencers and other devices. The manual Gate Width control determines the length of each note, or it can be controlled by the width of the pulse at the Clock input. Direction of the pattern can be selected Up, Down or Up/Down, and changed in real-time. The pattern can include just the notes being held, or those notes plus the next octave up.

Portamento (Glide) provides a gradual transition between notes as they change. Speed of the glide can be controlled manually as well as the curve type - Linear or Exponential.


Controls and Connectors

    Q175 MIDI Interface Aid usage
    MIDI Merge Input
      MIDI data at this input is merged with MIDI data from the MIDI input on the Q174. Data from both ports is processed as if it is coming from a single port. This provides easy connection for multiple controllers. MIDI data that does not match the jumper-selected channel number is ignored just as with the other MIDI input.

    MIDI Thru

      MIDI Thru output is a buffered copy of the MIDI data that comes into the MIDI input on the Q174. This can be used to daisy-chain MIDI Interfaces or to send data to external MIDI devices.

    Arpeggiator Pattern Switch

      Select either one or two-octave patterns. When "1 Oct" is selected, only the notes being held down are played. When "2 Oct" is selected, the notes being held down and the notes one octave above are played. The "Off" position turns the Arpeggiator system off.

    Arpeggiator Direction Switch

      This switch selectes the direction of the note pattern played. Options are Up, Down, and Up/Down. This selection can be made while a pattern is being played.

    Arpeggiator Speed

      Manual control of the Arpeggiator's speed. When near zero, the Arpeggiator's internal clock is turned off and only external clock pulses will advance the Arpeggiator system.

    Arpeggiator Gate Width

      Manual control of the Gate width (the length of each note) produced by the Arpeggiator's notes. When using the external clock input, the width of that pulse determines the Gate width.

    Arpeggiator External Clock Input

      An external clock input can be used to advance the Arpeggiator system. Typically this is a Pulse waveform from an oscillator. The width of this pulse determines the Gate output width. When the internal oscillator is running along with pulses from an external clock, both contribute to advancing the Arpeggiator system resulting in interesting timing.

    Portamento Speed

      Controls the Portamento (glide) speed between notes from zero to approximately 1 second.

    Portamento Curve

      Selectes the type of curve used to glide between notes. Linear and Exponential provide slightly different responses. Portamento operates with Arpeggiated notes also.


Panel Size:  Single width 2.125"w x 8.75"h.
Arpeggiator Speed Control:   1hz - 100hz
Arpeggiator Maximum External Clock Speed:   1Khz
Arpeggiator Gate Width Control:   5% - 95%
Portamento Speed:   1s - 50ms
Portamento Resolution:   100hz


Data Sheet
Click Here for data sheet in PDF format.


$130.00 US.


Usage and Patch Tips

Two MIDI controllers are used in this example. One could be a keyboard, the other a ribbon controller. Data from the first MIDI input is sent Thru to the next MIDI device if needed. Messages from both MIDI inputs are merged inside of the Q174/Q175 to produce control voltages. MIDI messages not matching the jumper-selectable channel number are ignored.

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In this example, Mode 2 is used to produce control voltages from two separate keyboards driving two separate synthesizer voices.

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Feel free to suggest more examples

End of Product Information