Saturday, October 26, 2013

The Terpstra Keyboard

Just noticed today that Synthtopia has a feature about the Terpstra Keyboard:

Which prompted me to visit their Indiegogo project page here:

The most interesting models to me are:

Get the full 5 "octaves" version of the Terpstra Keyboard.

Get the full 5 "octaves" version of the Terpstra Keyboard,
that can be upgraded with the color changing keycaps.

Uncovering the other Terpstra Keyboard Prototype

"Video showing more of the keyboard's expressive possibilities shot by Garnet Willis at Noisetree Studios in Toronto. This is the first video showing the Terpstra in a professional production studio, where Garnet uses it for composition and performance for film, TV, and dance. You'll notice that velocity sensitivity is clear in the composition."

Another performance demonstration:

Discovering the Terpstra Keyboard prototype

Seems to play very fluidly in 19 and 31 equal, although with some accompanying audible level of key clicking noise with this particular prototype version.

Update 1:
The below image from the Cortex Design site shows the back panel of the instrument, which reveals that it has 1/4" jacks for an expression controller and a pedal switch, as well as MIDI I/O.

For what it may be worth, I use the Pianoteq plugin, which works with both a continuous controller sustain pedal, as well as a switch style sustain pedal as featured on the Terpstra Keyboard; the former being preferable for really finessing the pedaling technique, although the latter is also serviceable and perhaps more common.

Update 2:

What's up with those clacky keys?

"I have fielded a few questions from people concerned about the noise of the keys in the videos posted online. Rest assured we will address the issues, but in the interest of disclosure and putting potential backer's minds at ease, here is a brief of what causes the noise and what we plan to do about it.

1) When releasing a keystroke by gliding your finger off its edge, the key releases quickly and the colored keycap rattles. The keycaps shown in the video are powder-coated steel caps, held in place with weak ceramic magnets. The weakness was intentional, as I did not want to interfere with the stronger neodymium magnets directly below them that interact with the Hall effect sensors that sense key position.
In the new design, we plan to retain the keycaps entirely differently, using a plastic snap fastener molded into the keycap itself. That should take care of that (and the keycap that falls out of its place in the video, as one observant musician noted).

2) The keyboard in the video needs recalibration of the keys. Over time, some sensor drift is anticipated, and as such the keyboards were programmed with a calibration procedure to sense the top and bottom of their full range of travel. Mike reported having to push the individual keys fairly deep into their keystroke to send a note-on event. As a result, he was playing the keyboard hard and bottoming out the keys. Recalibrating should fix this issue and the keyboard becomes more responsive. I expect in the next rev of keyboard firmware, we will be able to implement an auto-calibration so this step can be skipped."

But I wonder if visitors would agree - or not - that it is unfortunate that this controller seems primarily focused on piano-and-organ-style gesture, and doesn't include a pitch-wheel, mod-wheel or joy-stick controller? 

As one can see, some models bundle in the Einklang virtual instrument. I wonder how other musicians would add in real-time expressive musical gestures - such as via a pitch-wheel, mod-wheel / joy-stick controller - of the type found almost universally on keyboard controllers these days. Suppose they could be added in and merged as external MIDI devices, but this could potentially add an extra layer of hassle for musicians and composers used to having them available built right into most keyboards.

This is the only little thing that would make me reluctant to buy one, since using a pitch or mod-wheel as an expressive aspect of keyboard performance is something that I would generally consider an essential feature. And for what it may be worth, I prefer wheels to joy-sticks.

The price for either of the above two is comparable to what I gave for my AXiS-64 from C-Thru Music, however, the AXiS-64 does actually include two assignable controller wheels: one spring-centered wheel for pitch-bend, and the other a mod-wheel.

The AXiS-64 from C-Thru Music is a 192 key hexagonal array generalized 
keyboard featuring pitch-bend and mod-wheels, and two rotary controls.

There's little doubt though that the Terpstra will have far superior key action and velocity response than the AXiS, although the original inventor, Peter Davies of The Shape of Music, seems to have made significant key-action improvements to this type of hexagonal array generalized keyboard with his Opal model, which also happens to feature MIDI assignable wheels.

Both the Opal Chameleon and Opal Gecko have a 192 key hexagonal array generalized
keyboard, feature pitch-bend and mod-wheels, and (what appears to be) five rotary controls.


  1. Each key on the Terpstra is a highly expressive continuous controller. Pressure sensitivity is a good way to fake velocity sensitivity; the Terpstra keys are actually position sensitive, meaning that the controller "knows" the exact position at any point along the keystroke.

    With other words, each and every key acts just like a pitch-wheel, mod-wheel or joy-stick controller. You can assign pitch and modulation to any 2 keys and use them for that, or you can assign this to every key, to perform music in completely novel ways.

    For example, you could make it act like blown instruments, where the harder you blow another overtone is emphasized. By setting trigger points along the keystroke, every key could act just like that, playing different harmonics depending on depth. The possibilities and applications are limited just by imagination.

  2. Welcome Bogdan and thanks for dropping by to share these insights. It is no doubt going to be a highly expressive instrument and I look forward very much to all of the good music that will be created with the ones that will be built.

    Having played some different wind instruments down through the years, I'm keenly interested in being able to play harmonics according to breath pressure, and have actually built this into the Xen-Arts Ivor and XenFont VSTi, but in these cases it is velocity that is able to break out the harmonics, although it has occurred to me that future evolution of this feature should allow the user to freely route whatever controllers are desired. Surprisingly, not many virtual instruments I'm aware of (in fact none I've seen so far) have this kind of ability to play harmonics of the fundamental pitch.

    Please feel free to keep in touch.

  3. I heard Terpstra is going to have its own Janko WYSIWYG notation. This combination will ring in the dawn of a new era in musical creativity!
    Most innovative keyboards, such as Japanese Chromatone lack appropriate notation and buyers don't know how to learn to play them. Not good, is it?

  4. Welcome Johannes,

    This does sound like a thrilling development. Were can one read more about this notation system as will be implemented for the Terpstra keyboards?

    BTW - Very impressive whistling skills! :)