Tea-Chest Bass

Wed, 10/07/2026 - 12:00 — AdrianFreed

Series: alt.ctrl activities; builds on Gametrak and Tea-chest bass; Spatial arrangement

Stopped-string instruments can be simulated by extending a tether, pinning it down, and adding an angled fingerboard. This one simulates a tea-chest or washtub bass. In the paper's photograph of its version, the Gametrak Chordophone, the fingerboard is a long pole whose foot is taped down beside the Gametrak.

A player holds a long blue pole angled up from a table. Its foot is taped down beside a Gametrak, and a red tether runs from the Gametrak up along the pole to the player's upper hand, while the other hand plucks it.
The Gametrak Chordophone, from the SMC 2009 paper.

Materials

ItemAmazoneBay
A Gametrak controller (originally sold with two gloves and a footswitch)search
A long pole, as the fingerboard
Tape, to fix the pole's foot (as in the paper's photograph)
A computer with Max/MSP or Pd

Tools

Skills

  • Stopping and plucking a string, as on a washtub bass
  • Detecting plucks in controller data
  • Mapping position to pitch as MIDI note numbers

Instructions

  1. Set the Gametrak up as in Set Up a Gametrak for Music.
  2. Fix the foot of the pole beside the Gametrak, angled up toward the player.
  3. Pull a tether out along the pole and pin its end at the top, so that it runs taut along the pole like a string.
  4. Play it like a tea-chest bass: stop the string against the pole with one hand, and pluck it with the other.
  5. Detect plucks: each shows as an impulse on the tether's x and y axes, and its size tells how far the string was pulled from its average position.
  6. Map the readings to pitch - linearly as MIDI note numbers, fractional MIDI for continuous pitch and remap nonlinearly to match a familiar string instrument. You can either remember position before the pluck or wait until the position stabilizes after the pluck to define the pitch.

Variations

  • Dismantle each sensor from multiple Gametraks and rearrange them to be closer together for applications with more than 2 strings, as in the Kotrak.

Related resources

Coding Prompt Build Block

A prompt to give a coding assistant, to start the code for this activity. Copy the box, answer its questions about your board and pins, and test what comes back on the bench before you rely on it.

I am building "Tea-Chest Bass", the activity at https://adrianfreed.com/tea-chest-bass.html.

Write a Max or Pd patch, or a program, for a Gametrak tether pulled out along an angled pole and pinned at its top, played like a tea-chest bass: stopped with one hand and plucked with the other.

Detect plucks: each shows as an impulse on the tether's x and y axes, and its size tells how far the string was pulled from its average position, so keep track of that average. Map the readings to pitch linearly, as MIDI note numbers (fractional ones give continuous pitch), then remap them nonlinearly, as a familiar string instrument might. Take the pitch either from the position remembered before the pluck or from the position once it settles after the pluck, and make that choice a setting.

Libraries to explore:

Before writing anything, ask me what I am using: the board and its pins, or the software (such as Max, Pd or Python), and check its documentation for what this needs. Put the pin numbers, ranges and other settings in one block at the top, each with a comment. Say which of the libraries above you use, and why. Start with a test that shows the raw readings, so that I can check the wiring and the ranges before the rest.

This activity by Adrian Freed is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0): you may share and adapt it with attribution, for non-commercial purposes such as personal projects and teaching, and you must share adaptations under the same licence. Product names and links belong to their suppliers.

Design strategies: