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2 items	Korg EXP-2 Current	Korg PU-2 Current
General
Manufacturer	Korg	Korg
Status	Current	Current
Price	£59	£59
Pedal
Pedal type	Expression	Sustain
Style	Rocker	Piano-style
Pedals in unit	1	3
Connection
Connector	1/4" TRS	Proprietary
Polarity switch	No	No
Range / minimum control	Yes	No
Build & features
Housing	Plastic	Plastic
Features	Range control, Rubber base	—
Designed for	Korg keyboards, modules and effects; most expression sockets	Korg B1, SP-280, LP-180
Size & weight
Colours	Black	Black
Dimensions (W × D × H)	87 × 200 × 92 mm	234 × 152 × 73 mm
Weight	0.46 kg	0.72 kg

Glossary

48 terms

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Basics

MIDI: 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 2.0: 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.
DAW: 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 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 price: 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-action: 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-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-action: 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 keys: Keys the same width as a piano's (about 23.5 mm per white key). Most 49-key-and-up controllers use them.
mini keys: 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 keys: In-between keys – full length but slightly narrower than piano keys – used on some compact synths and controllers.
velocity: 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 aftertouch: 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 aftertouch: 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.
MPE: 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 buttons: Shift the whole keyboard up or down in octaves so a small controller can still reach the full note range.
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

pads: 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 launching: Triggering loops and scenes from a grid, Ableton Live Session View style. Grid controllers like the Launchpad and APC exist mainly for this.
faders: Sliders, typically nine (eight tracks plus a master) mapped to mixer levels or drawbars. 60 mm is the usual travel on controllers.
knobs: 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.
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 bend: 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 wheel: A free-moving wheel that sends a continuous control – conventionally vibrato depth, but assignable to anything.
touch strips: Flat capacitive ribbons standing in for pitch and mod wheels on slim controllers. Lighter and cheaper, with less tactile feedback.
joystick: A single stick doing pitch bend on one axis and modulation on the other. Saves space on mini controllers.
arpeggiator: Holds a chord and plays its notes one at a time in a pattern, synced to tempo. Handy for instant rhythmic parts.
sequencer: Records and plays back a pattern of notes from the controller itself – useful for driving hardware synths without a computer.
scale mode: 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 mode: 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 repeat: Holding a pad retriggers it in time with the tempo (8ths, 16ths, triplets…) – the MPC trick for hi-hat rolls and trap hats.
display: 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.

Connectivity

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 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 MIDI: The classic round 5-pin MIDI socket. Lets a controller talk to hardware synths directly, with no computer in the chain.
TRS 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 / Gate: 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 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 pedal: A ¼" jack for a piano-style on/off foot pedal that holds notes after you release the keys.
expression pedal: A ¼" jack for a continuous (rocking) foot pedal – volume swells, wah, or any parameter you assign.
footswitch: A generic on/off pedal input, assignable to things like start/stop or patch change rather than sustain.
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 mode: 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.