Music Keyboards Guide

There are many electronic music keyboards that feature what are often called “weighted keys” which are supposed to imitate the key action (how the key behaves when pressed) of an acoustic piano. Because there are a variety of tastes and playing styles, a few different technologies have been developed to simulate the feel and response of acoustic piano keys. Here is a more in-depth look at the various weighted keyboard action technologies available.

It will help to first briefly look at how acoustic pianos create sound. The mechanical means by which pianos make sound have been developed over several centuries. A rather complex combination of many components bring a damper to lift off of the strings to allow them to vibrate freely and bring a hammer to strike the piano strings when a key is pressed. The mechanism allows the hammer to strike the string at various levels of intensity to create differences in dynamics (this is known as velocity – or touch – sensitivity) as well as the ability to repeat notes quickly (through the use of double escapement action). These mechanisms allow the piano player to produce a variety of tonal characteristics and expressive nuances.

The challenge for today’s electronic keyboard manufacturers has been to recreate the key action of acoustic pianos in a portable instrument while keeping the size and weight of the instrument down. The advantage of electronic keyboards is that the key mechanism only has to make an electrical contact when the key is pressed as opposed to tapping on strings. This, together with the technological advances of electronic sound amplification and digital signal processing to create sound instead of piano strings and a sound board, allow for a more simplified keyboard mechanism that takes up less space and allows for a lighter, more portable instrument.

Graded-Hammer Action

On an electronic weighted keyboard featuring the most realistic key action you will find what is typically known as graded-hammer action, a term used by manufacturers such as Yamaha, Kurzweil, M-Audio, Kawai, and Korg. Roland uses the term progressive hammer action and Casio uses the term scaled hammer action which are all the same thing. This technology delivers the experience that the keyboard of an acoustic grand piano gives where the keys at the lower registers feel heavier than those in the upper registers; in other words, the keys have a progressively lighter touch (or provide less resistance) as you play from the left side to the right side of the keyboard. The hammers that hit the bass strings are bigger and create more resistance when played than those of the treble strings. Also, the keys in the lower register have a delayed response.

The term hammer action refers to the way the hammer mechanism on an acoustic piano strikes the piano strings in a hammer-like fashion to create sound. Although not constructed the same as that of an acoustic piano, the keys on hammer action electronic keyboards also employ a hammer-like mechanism that emulates the resistance and response of acoustic piano keys. The hammer action mechanism is designed to not only mimic the resistance and feel of playing an acoustic piano but also to recreate certain action characteristics such as how the key returns to its rest position when released, velocity sensitivity, and double escapement action which allows for the rapid repetition of notes. Classically trained pianists prefer the graded-hammer action technology in electronic keyboards because this is what they are used to. Graded-hammer action also allows for the widest variety of expressive techniques and nuances, many of which can truly only be created and heard on an acoustic piano.

Wooden-Key Action

The most expensive electronic music keyboards, particularly those that are designed with “mini-grand” or “baby-grand” piano cabinetry, will often feature what is known as wooden-key action. The keyboard features graded-hammer action but the keys are made of wood. Most graded-hammer action keyboards have keys made out of plastic with a combination of weights, the hammer mechanism, and other design components that together create the resistance of acoustic piano keys. The wooden keys, together with the other components, create a more authentic touch than non-wooden keys largely because of the added density and shape of the wood. Yamaha, Kawai, and Roland are three manufacturers that offer wooden-key action on their higher-end digital keyboard instruments.

Weighted Balanced Hammer Action

Some musical keyboards have equally weighted keys throughout the entire range. These keyboards are typically designated as weighed-hammer action, balanced hammer action, or a combination of the two names. They feature the hammer mechanism as well as other components to simulate the resistance of acoustic piano keys, but each key is equally weighted. This kind of key action appeals to those who like the weight of acoustic piano keys and prefer a balanced, even touch response throughout the entire keyboard range. For many keyboard players the graded-hammer action is physically too demanding, and a balanced hammer action is more comfortable.

Semi-Weighted Action

Semi-weighted action keyboards not only have keys with lower resistance than a fully weighted keyboard, but the way the key behaves is different too. Semi-weighted keys use a spring instead of a hammer mechanism to create resistance. This causes the key to quickly spring back to its resting position when released. Semi-weighted keys are essentially a hybrid of weighted action and synth action (see below). They also have equal resistance throughout the keyboard’s entire range. Semi weighted keyboards appeal to those who prefer the “springiness” of synth keys with some of the weight of weighted keyboards.

Many keyboards also have velocity curves which allow one to adjust the sensitivity of the keys in terms of how the dynamics (levels of volume) respond to the force with which the key is pressed. For example, to comfortably play the same pianissimo dynamic, someone who is used to playing the keys lightly will require a different velocity setting than a player with a heavier touch (who, perhaps, has heavier, stronger hands or is used to playing acoustic pianos and hitting the keyboard harder). If you’re used to playing an acoustic piano and you start playing a semi-weighted keyboard, the same force you used to play soft dynamics on an acoustic piano will create louder dynamics on the semi weighted keyboard, and vice versa. You’ll typically find velocity curves on balanced hammer action and semi-weighted keyboards.

Synth Action

Music keyboards with synth action have the least amount of resistance of all the weighted keyboard types. They exclusively use a spring mechanism to allow the key to spring back quickly when released. There is no added resistance, per se, other than that which is built-in to the key mechanism by default. In other words, there is no resistance added intentionally with weights or specific mechanisms who’s purpose is to add resistance to the keys. You will find synth action on many electric organs such as Hammond organs, Farfisas and other combo organs, most synthesizers and MIDI controllers (although some manufacturers such as M-Audio do offer semi weighted MIDI keyboard controllers). A lot of the more inexpensive arrangers and workstations feature synth action as well. Keyboard players who are used to synth action and/or like to play very fast riffs and solos prefer this type of keyboard action or also the semi-weighted option.

Which type of weighted keyboard technology one chooses will depend on mainly two things. The first consideration is the individual player’s preferences on factors such as key resistance, release response, touch sensitivity, and weight gradation across the keyboard range. The second consideration is the style of music. Classical piano and jazz repertoire is better suited for graded-hammer action keyboards whereas classical organ music will be easier to play on balanced semi-weighted keyboards. Ultimately, the functionality and purpose of the music keyboard is what determines which weighted keyboard technology it uses: digital pianos make use of graded-hammer action whereas MIDI keyboard controllers use synth action. In many cases, some musicians will require more than one keyboard instrument in order to fully realize all of their performance styles on a gig or in the studio.