|
TACTEX
CONTROLS MTC
EXPRESS
|
 |
 |
 |
|
FIG. 2: The same pressure points on the pad can be interpreted in a variety of ways, depending on the computer algorithm used. |
Fig. 2 shows how the same left-hand position on the pad can be interpreted differently, depending on the computer algorithm. Fig. 3 gives an example of how the pad can be used for tracking a moving point across the pad. Those visual examples show the variety of ways the MTC Express can be used. In the context of musical control, they suggest an array of exciting possibilities.
For example, the control surface can be set up as multiple dynamically interactive control areas. In one mode, the pad’s surface can be used as a collection of virtual volume faders, like on a mixer. In another mode, note density and filter settings for a synthesizer can be controlled by finger position and pressure.
I wanted to use the pad to develop a map of virtual keys across the surface. The layout was based on the tonality diamond of microtonal-music pioneer Harry Partch. When I discerned the scanning pattern of my Tactex object, I was surprised to see a stream of numbers coming from locations I had not been touching. The MTC Express owner’s manual revealed that I needed to normalize the pad before using it so that a baseline surface pressure could be determined.
Normalizing the pad eliminates the individual variability in taxel response. The procedure can be automated in software and made part of the initial startup of software using Smart Fabric. Once normalized, the taxels’ range of pressure response is 0 through 1,023. This degree of accuracy is finer than the 0 to 127 data byte of a standard MIDI controller. After I normalized the pad, I received reliable results.
In my review unit, some taxels were slow to recover after being touched. When an area is depressed, each taxel should return immediately to its normalized state. However, that didn’t always happen. The manufacturer says this problem has been fixed on subsequent pads.
Once properly calibrated, the pad sends out two numbers for each taxel that receives pressure. The first number represents the location, and the second is the degree of pressure. As pressure and location change, the new values transmit with the next scan.
After I finished creating my tonality diamond, I built a mixer control surface. I then realized that those different designs could be separate states within a single instrument design. The possibilities are staggering.
 |
|
FIG. 3: The MTC Express can be programmed to follow the trajectory of as many as five pressure points across the pad’s surface. |
FUTURISTIC SCRATCH PAD
MTC Express’s most intriguing aspect is that it provides continuous control of multiple user-definable parameters simultaneously. Imagine controlling pitch, filter cutoff, and synth amplitude at the same time without adapting traditional keyboard performance techniques. This could lead to specialized instruments based on a synth’s capabilities, rather than outdated acoustic models.
An attractive attribute of the pressure-based approach of the MTC Express is its physicality. The performer deals with the surface in a discreet way, so the music is the direct result of fine muscle control and purpose, which have always been the prerequisites of making music but have been limited by most electronic controllers. The MTC Express is a great tool for realizing the promise of electronic musical-instrument design.
Scot Gresham-Lancaster is an electronic technician, computer-music lecturer, and recording engineer at California State University at Hayward’s music department, as well as the fuzz in the electronic-music trio, Fuzzybunny.
Reprinted with permission from
Magazine, May, 2001© 2000, Intertec Publishing, A Primedia Company All Rights Reserved
[an error occurred while processing this directive]
