TACTEX CONTROLS

MTC EXPRESS

A new generation of controllers through the magic of Smart Fabric.

By Scot Gresham-Lancaster

FIG 1: The Tactex MTC Express comes with a cross-platform application program interface for creating instruments and controllers
(click image for larger view).

There have been a number of developments in controllers that work beyond the MIDI specification’s confines. An important new entry in this field is Tactex Controls’ MTC Express (see Fig. 1). The MTC Express features a pad made from Smart Fabric, a soft material that gives users a multipoint, three-dimensional control surface. The result is a programmable controller that is highly responsive and lets musicians realize the potential of electronic instruments.

INSIDE THE PAD
The MTC Express’s Smart Fabric is based on a patented pressure-sensing technology developed by the Canadian Space Agency. Smart Fabric consists of thin cellular elastomers, typically made of urethane or silicon, with an outer skin that protects the fabric and serves as a wear surface. Intended for space-based robotics, the fabric provides touch-based feedback to remote telerobotic operators.

Within the Smart Fabric are overlapping pressure sensors, called taxels, connected to fiber-optic cables. An LED generates a measured amount of light, which is sent to the taxels through the fiber-optic cables. Pressure on the taxels restricts the flow of light. Each affected taxel returns a reduced amount of light to a light sensor, which tells the unit’s CPU the amount of pressure exerted in a specific location.

Product Summary

Tactex Controls

MTC Express

control surface

$495

Features	4.5
Documentation	4.0
Ease of Use	3.0
Value	4.5

Rating products from 1 to 5

PROS: Good for designing customized controllers. Senses and tracks five contact points simultaneously. Includes application program interface.

CONS: Taxels sometimes slow to recover from pressure. Not for novices. Requires knowledge of the C-programming language or the Max/MSP programming environments.

Manufacturer

Tactex Controls

tel. (250) 480-1132

e-mail sales@tactex.com

Web www.tactex.com

The MTC Express’s active area contains a grid of 72 taxels, with taxels spaced about one centimeter apart. Although future Smart Fabric products can be almost any size and configuration, the MTC Express has a 5 3/4-by-3 3/4-inch control surface, which is roughly the size of a mouse pad or a small Wacom art tablet.

GENEROUS CODING
The MTC Express includes the necessary hardware and cross-platform application program interface (API) for developing custom instruments and controllers. The API consists of a set of C-language libraries to which developers can link their custom code.

Cycling 74’s Max and MSP are the best environments for developing your ideas for the MTC Express. Researcher Matt Wright and others at the Center for New Music and Audio Technology at the University of California at Berkeley have created external drivers for the Max graphical programming environment.

Most of the development work in Max has been to create external objects that include the MTC Express Pad as an input. Of course, a resourceful programmer can make application-specific input drivers for any Mac or PC program by using the API libraries.

After I unpacked the controller and installed the Tactex object, it only took me five minutes to get things working enough to receive coordinates and pressure readings when I touched or tapped the pad. I am an experienced Max programmer, but a novice user could use the Tactex pad to create custom controllers within a day.

MTC Express Specifications
Pressure Resolution	8 bits
Transmission Rate	115 kbps
Minimum Activation Pressure	0.4 psi
Connector	DB9 or Mac serial adapter
Dimensions	0.8” (H) 5 7.5” (W) 5 6.69” (D)
Weight	17 oz.

Reprinted with permission from

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