MIDI Controllers: The Key, The Secret
How your keymech is crucial to your creative process
Words: Chris Mayes-Wright & Paul Whittington
Keyboard controllers sit at the center of most studio setups as the de facto device used to play MIDI parts and enter parameter information into a DAW. Some have lots of MIDI-assignable controls, others have drum pads, many have both and much more aside. What they all share is a keymech, the component that holds the keys, actuators and sensors that convert a player’s physical input into data that your DAW can work with. (The keymech is also sometimes known as a ‘keybed’ or, confusingly, the ‘keyboard’.)
Not all keymechs are made equal. Of course, there are full- size and mini-key variants, but beneath the standardised piano-key facade, there are many factors at play that govern how a keymech feels and how it responds to being played. In this article, we aim to lift the lid on keymechs, cover the terminology used to describe them, and explain some of the processes in action.
Terminology
When it comes to describing keymechs, there are a number of commonly used (and mis-used) terms for differentiating them. In fact, while reading this guide, you may come across something that goes against other information on this topic. The fact is that there is a huge amount of mis-information in the public domain, especially when it comes to the terminology about key styles, actions and weighting. This guide comes to you from the mouth of Novation’s product development team, from conversations with Paul Whittington, an engineer who’s been designing keyboard controllers for two decades. We’ve done our best to avoid marketing jargon here, to give you the real scoop on what makes up your keymech.
Key Style
This refers to the literal shape of the key. (Nothing else.)
Piano Style — A piano-style key has a flat front profile and an overhang/lip, just like on a traditional piano.
Synth Style—Synth-style keys have a tapered or cut-away underside, which typically makes them lighter and faster to respond.
Organ Style/Waterfall—Keys with a rounded-off corner lip, just like the ones you find on a Hammond organ or similar. Like piano-style keys, they also have a flat front profile.
Action
This term describes how the key is anchored and hinged to the body of the keymech. It’s one of the most important things to get right in keymech design, as it has a substantial affect on how the keys will feel when played. However, it’s just one of a number of factors that complete the keymech experience.
Single-hinge action—Single-hinge designs are just that: each key hinges at the base of the keymech and returns back to its resting position with no assistance. Due to the simplicity of this design, single-hinge keys can help controller manufacturers to keep costs down. But single-hinge designs don’t always feel cheap: a well-engineered keybed of this variety can be a synth player’s dream, due to its quick response.
Sprung action—In this design, each key is a lever that pivots on a hinge and is returned to its resting position by a spring, which contracts to pull the lever back to the default state.
These components cost more, and are often found in premium controllers, but do not guarantee a superior feel. The way a controller ultimately feels is down to a number of other factors (read on for more information about these).
Hammer-action — Hammer-action keys mimic the mechanism and performance of a piano key, and have numerous moving parts. In a piano, the hammer is the felt-covered actuator that strikes the piano string(s).
In a MIDI-enabled hammer action key, the hammer — or another part of the mechanism — strikes a set of switches, the output of which gets translated to MIDI information.
Weighting
There are lots of misconceptions and misleading terminology used around the weighting of keys. A key that is hard to press is not (necessarily) a weighted key. In fact, the opposite is often true. A weighted key will usually feel lighter to the touch, but recoil slower, due to the increased resistance on the spring or hinge. We know, it’s complicated. All these factors affect the way the keymech feels to the player, and will change how quickly they can do things like play glissandos (glides up and down keys), for example.
Unweighted—An unweighted key relies purely on the mechanical attributes of its action (whether single-hinge or individually sprung) for the way it feels.
Single-weighted—Adding a small weight to a key (usually by gluing it to the key’s underside) decreases the amount of effort needed to press it, and therefore determines the extent to which it resists when pressed and how quickly it returns to a resting position. The term ‘semi-weighted’ refers to any keymech design that uses weights in this manner.
Hammer-action—Piano-style, hammer-action keys are normally not artificially weighted; it’s the mechanical process that gives a piano-action keyboard its ‘heavy’ feel.
Velocity Curve
The Velocity Curve is arguably the most important factor in making a keymech ‘playable’. It is actually a programmed behavior that is coded in the firmware of a keyboard controller, which determines how the physical input of the human player is converted into fairly crude digital MIDI information. Often, there are a number of Velocity Curves available on a keyboard controller (there are four selectable behaviors in every Novation Impulse, for example). These alter the keyboard’s response, and help to pair the player’s style with the sound module or plug-in being used. If using a controller to play a grand piano, for example, the player may want a velocity curve that requires a lot of effort to hit the highest velocities, just like with a real piano. A soft synth — which might not have a lot of dynamic range and which sounds best with a more uniform velocity — may work best with a more linear velocity curve.
Scan rate
This is another non-mechanical attribute of the keymech design, which describes the speed at which the controller’s processor senses signals from the switches on each key. A fast scan rate will allow the processor to create a more dynamic Velocity Curve, because it can detect smaller differences in actuator timing. This results in more accuracy in the higher end of the Velocity Curve. As an example, the Novation Impulse has an unusually high scan rate of 10kHz (10,000 times per second), giving it the ability to discern the minute temporal differences when the keys are pressed with great force.
Hopefully this short primer helps you to understand the ins and outs of keymechs. We hope this gives you more knowledge so you can make the right decision when choosing a keyboard controller for you. You can find out more about Launchkey here.
