Aftertouch, Channel Pressure, and Key Pressure

  • All,

    I know there is a lot of misunderstanding about Key Pressure and Aftertouch (for the search engine here: After Touch too).
    And you will find a lot of information mixing things together - not only here but everywhere in the Web.

    Here is what the Virus (at least Ti and Ti2) is doing what:

    - Key Pressure (CC129) is doing the modulation as expected: Pressing a key or multi keys will do the modulation as programmed in the Virus Matrix

    - Aftertouch (CC131) manipulates the OSC3 setting of the Virus

    Very often, if people talk about Aftertouch, when they mean Key Pressure - or Channel Pressure as it is usually called (see Matrix programming on the Virus)

    So do not get frustrated (as somebody who asked me) if the result is not what is expected.

  • So key pressure here is the term for velocity?

    Velocity is the speed or softness how you press a key - just before the Key Pressure start.

    - Example Piano: soft touched key plays subtle soft note - fast and less subtle will play a full accented note (all depending on what is assigned to Velocity in the Virus)

  • Never heard the term Key Pressure with regards to Control Change messages before and don’t know what OP is talking about either.

    Aftertouch comes in two flavours: Channel Pressure and Polyphonic Key Pressure, which both are a separate class of events unrelated to Control Change messages.

    Refer to the MIDI implementation chart from the MIDI Association.

    Bass Player and Synthesist.
    Virus TI2 Darkstar | Virus TI2 Desktop | Sub 37 | Voyager RME | Machinedrum | Analog Four | Digitone | MPC Live | NI Maschine+
    Mac OS 13.5.1 (Ventura) | Cubase Pro 11.0 | Ableton Live 9.6 | Logic 10.4 | MainStage 3.4 | NI Komplete Ultimate 13 | RME Fireface UFX+

  • OK, you are right, let's call it the correct name: Polyphonic Key Pressure

    The 16 pads of MPCX can trigger exact these midi signals for Polyphonic Key Pressure - individually for every voice poly phonically - CC131. This causes the parameter change of OSC3 of the Virus Ti - not sure whether this was an accident of the Access programmers?

    This is what CC131 is for.

    My PolyBrute react exactly as it should - 6 voices individually ploy phonically triggered.