Reference

The glossary

Every bit of jargon that turns up on a keyboard or controller spec sheet, explained once, properly. 49 terms.

These definitions also appear inline across the site: anywhere a term is highlighted, hover it to read the definition without leaving the page.

Basics

MIDIalso: MIDI controller, MIDI controllers: Musical Instrument Digital Interface, the 1983 standard for sending notes, knob movements and timing between instruments and computers. A MIDI controller makes no sound of its own; it sends MIDI to software or hardware that does.
MIDI 2.0also: Property Exchange: The 2020 update to MIDI: two-way communication, far higher resolution for velocity and controllers, and Property Exchange so a controller can ask a synth or DAW what its parameters are and label its knobs automatically.
DAWalso: DAWs: Digital Audio Workstation, recording and production software such as Ableton Live, Logic Pro, FL Studio or Cubase. Most controllers ship with scripts that map their controls to popular DAWs.
DAW transportalso: transport: Dedicated play, stop, record and loop buttons that drive your DAW, so you can punch in without reaching for the mouse.
HUI: Human User Interface, an old Mackie control-surface protocol that almost every DAW still understands. Controllers fall back to it for DAWs they have no custom script for.
list pricealso: RRP, MSRP: The manufacturer's published recommended price (RRP in the UK, MSRP in the US). Shops usually sell for less, and it excludes any tax or shipping differences between regions.

Keys

keybed: The mechanical keyboard assembly itself, the keys, their pivots and the sensors under them. Two controllers with the same key count can feel completely different because of the keybed.
synth-actionalso: synth action, synth-style: Light, springy keys with no added weight, fast for synth lines and drums, less piano-like. The most common action on controllers under 61 keys.
semi-weightedalso: semi weighted: Synth-style keys with extra weighting or damping so they feel a little more substantial than plain synth-action, without the full mechanics of a piano action.
hammer-actionalso: hammer action, fully weighted, graded hammer: A piano-style mechanism with small hammers that give the keys real inertia. "Graded" means heavier in the bass and lighter in the treble, like an acoustic piano.
full-size keysalso: full size, Full: Keys the same width as a piano's (about 23.5 mm per white key). Most 49-key-and-up controllers use them.
mini keysalso: mini-keys, mini key, Mini: Narrower keys (roughly 80% of piano width) that let a 25- or 37-key controller fit in a laptop bag. Fine for melodies and bass; awkward for two-handed piano playing.
slim keysalso: Slim: In-between keys (full length but slightly narrower than piano keys) used on some compact synths and controllers.
velocityalso: velocity-sensitive, velocity sensitive: How hard you hit a key or pad, measured by how fast it travels. Nearly every controller sends velocity; the quality of the curve is what varies.
aftertouch: Pressure applied to a key after it's already down, sent as a continuous control. Great for adding vibrato or swelling a filter while holding a note.
channel aftertouchalso: Channel: The common kind of aftertouch: one pressure value for the whole keyboard, so pressing harder on any key affects every note that's sounding.
polyphonic aftertouchalso: poly aftertouch, poly-aftertouch, poly AT, Polyphonic: Aftertouch measured separately for each key (or pad), so you can lean into one note of a chord without affecting the others. Still rare on keyboards, common on pad grids.
MPEalso: MPE surface: MIDI Polyphonic Expression, a way of using MIDI so each note gets its own pitch bend, pressure and slide. It's what lets the ROLI Seaboard bend individual notes. Needs an MPE-aware synth.
octave buttonsalso: octave up/down, octave range: Shift the whole keyboard up or down in octaves so a small controller can still reach the full note range.
zones / splitsalso: zones, split, layer, Zones / splits: Dividing the keyboard so different ranges (splits) or the same range (layers) play different sounds or MIDI channels, bass in the left hand, piano in the right.

Controls

padsalso: pad, drum pads, pad grid: Rubber squares for finger drumming or launching clips, usually velocity-sensitive and often pressure-sensitive with RGB backlighting. 8 or 16 pads on keyboards; 64 on grid controllers.
clip launchingalso: clip launch, clip-launch, Session View: Triggering loops and scenes from a grid, Ableton Live Session View style. Grid controllers like the Launchpad and APC exist mainly for this.
fadersalso: fader: Sliders, typically nine (eight tracks plus a master) mapped to mixer levels or drawbars. 60 mm is the usual travel on controllers.
knobsalso: knob, potentiometers, pots: Rotary controls with a fixed start and end (about 270° of travel). Cheap and direct, but the position may not match the software value when you switch presets.
encodersalso: endless encoders, endless rotary encoders, encoder, Knobs / encoders: Knobs that turn forever. Because they send relative "up a bit / down a bit" messages, they never jump the software value. Ideal for DAW and plug-in control.
pitch bendalso: pitch wheel, Pitch / mod, pitch and mod wheels, Wheels: A spring-loaded wheel (or strip, joystick or lever) that bends the pitch of held notes up or down. Usually paired with a modulation wheel.
mod wheelalso: modulation wheel, modulation: A free-moving wheel that sends a continuous control, conventionally vibrato depth, but assignable to anything.
touch stripsalso: touch strip, Touch strips: Flat capacitive ribbons standing in for pitch and mod wheels on slim controllers. Lighter and cheaper, with less tactile feedback.
joystickalso: Joystick, thumb joystick: A single stick doing pitch bend on one axis and modulation on the other. Saves space on mini controllers.
arpeggiatoralso: arpeggio, arp: Holds a chord and plays its notes one at a time in a pattern, synced to tempo. Handy for instant rhythmic parts.
sequenceralso: step sequencer: Records and plays back a pattern of notes from the controller itself, useful for driving hardware synths without a computer.
scale modealso: Scale mode, scale-locked: Restricts the keys or pads to a chosen scale so every note you hit is "in key". A safety net, or a way to play melodically on a pad grid.
chord modealso: Chord mode, fixed chord, chord map: Plays a full chord from a single key or pad, either a fixed voicing you set, or chords chosen to fit the selected scale.
note repeatalso: Note repeat: Holding a pad retriggers it in time with the tempo (8ths, 16ths, triplets…). The MPC trick for hi-hat rolls and trap hats.
displayalso: OLED, LCD, screen, Colour LCD: Screen for parameter names and values. OLED is the small monochrome panel on most mid-range controllers; a colour LCD shows more but costs more.
Hall-effectalso: Hall effect, Hall-effect switches, Hall-effect keys, Hall-effect buttons: A contactless way of sensing movement: a magnet sits on the moving part and a sensor reads the strength of its field, so nothing rubs and nothing wears out. Because the sensor reports how far something has travelled rather than just whether it has been pressed, a Hall-effect button or key can send continuous pressure or position as well as a note, and it will not develop the crackle or dead spots that eventually affect mechanical contacts and carbon-track faders.

Connectivity

USBalso: USB-C, USB-B, Micro-USB: The cable to your computer, carrying MIDI and usually power. USB-C is current; USB-B (the square printer plug) and Micro-USB are older but work identically with the right cable.
bus poweredalso: USB bus powered, bus-powered, USB-powered: Runs entirely from the USB cable, no power supply needed. Big 88-key boards or anything with a bright screen may need a wall adapter.
DIN MIDIalso: 5-pin MIDI, 5-pin DIN, DIN out, DIN in, MIDI ports, MIDI out, MIDI in: The classic round 5-pin MIDI socket. Lets a controller talk to hardware synths directly, with no computer in the chain.
TRS MIDIalso: TRS out, TRS in, 3.5mm MIDI, minijack MIDI: MIDI over a 3.5 mm headphone-style jack, used where a 5-pin socket won't fit. Needs a TRS-to-DIN adapter (Type A is the standard) to reach older gear.
CV / Gatealso: CV/Gate, CV/gate, CV / Gate out: Analogue control voltages for modular and vintage synths: CV sets pitch, Gate says when a note is on. A controller with CV/Gate outs can play a Eurorack system directly.
Bluetooth MIDIalso: Bluetooth, wireless MIDI: Wireless MIDI to an iPad, Mac or PC. Latency is a few milliseconds higher than USB, fine for most playing, and it frees you from the cable.
sustain pedalalso: Sustain, sustain input: A ¼" jack for a piano-style on/off foot pedal that holds notes after you release the keys.
expression pedalalso: Expression: A ¼" jack for a continuous (rocking) foot pedal, volume swells, wah, or any parameter you assign.
footswitchalso: Footswitch: A generic on/off pedal input, assignable to things like start/stop or patch change rather than sustain.
audio interfacealso: Audio interface, built-in audio interface: Audio in/out built into the controller, so it can also be your soundcard. Record a mic or synth and monitor through it.
standalone modealso: Standalone mode, standalone: The controller does something useful with no computer attached, sequencing hardware, or in Push 3 Standalone's case running Ableton Live itself.
NKS: Native Kontrol Standard. Native Instruments' format that lets a controller browse plug-in presets and pre-map their knobs. Supported by most major plug-in makers.
Light Guide: The strip of LEDs above the keys on NI Kontrol keyboards showing scales, drum-kit zones and key splits in colour.