Didgeridoo Design Cheat Sheet

This document gives a compact overview about didgeridoo design.

1. Bore Geometry (The Shape)

The internal shape is the “engine” of the instrument.

• Cylindrical (Straight Pipe):
  • Sound: “Clean,” “Pure,” or “Electronic.” It has very few overtones.
  • Characteristics: The drone is stable but can sound “thin.” Toots (overtones) are very high and difficult to reach.
• Conical (Tapered/Expanding):
  • Sound: “Rich,” “Warm,” and “Complex.”
  • Characteristics: The expanding shape creates many harmonic overtones. The toots are lower in pitch, making them easier to play and integrate into rhythms.

2. Backpressure Logic

Backpressure is the resistance that allows for circular breathing and lip control. Didgeridoos with high backpressure are easier to play than didgeridoos with low backpressure.

• The Mouthpiece: Should be 2.8 cm to 3.2 cm in diameter. Anything larger than 3.5 cm makes the drone difficult to hold.
• The “Neck” (The First 30 cm): This is the most critical area. Keep this section narrow (approx. 3 cm to 4 cm). If the bore expands too quickly here, you lose all backpressure.
• The Taper Rule: A gradual expansion (conical) provides a better balance of backpressure and volume than a sudden “step” in diameter.
• Shape: Conical didgeridoos have a higher back pressure than cylindrical didgeridoos
• Volume: The larger the volume of the didgeridoo, the lower the back pressure. Shorter didgeridoos will have a higher back pressure than longer didgeridoos,.

3. Wall Density & Thickness

The walls must be rigid enough to reflect energy back into the air column.

• Thin Walls: Tend to vibrate with the air, absorbing energy. This makes the sound “dampened,” “flimsy,” or “muffled” because it takes away energy especially at high frequencies.
• Thick Walls (> 1.0 cm): Provide a “sturdy,” crisp, and bright projection. Hardwoods (Eucalyptus, Oak, Ash) are superior to softwoods (Pine).
• Weight: The thicker the wall, the heavier the didgeridoo.

4. Internal Texture & Finish

The “roughness” of the inside affects the “color” of the sound.

• Smooth/Glassy Finish: (Varnish or Epoxy). Creates a fast, bright, and loud sound. Preferred for modern, percussive playing.
• Rough/Natural Finish: (Termite tracks or raw wood). Creates micro-turbulence. This results in a haunting, raspy, and traditional “earthy” tone.

5. Bell Flare

• The Bell: A flare at the end (expanding to 8 cm – 15 cm) increases volume and bass response without sacrificing the backpressure managed at the top.

6. Length

• Standard Rule: If you want a lower key (like a deep B or A), you need more length. If you want a higher, faster key (like F or G), you need a shorter tube.
• Straight, conical pipes: In a straight pipe, the relationship between length and pitch is linear. Cones need to be longer than cylinders to hit the same deep notes.
• The “Shortening” Effect of Conical Didgeridoos: A strongly conical didgeridoo can actually play a deeper note than a cylinder of the exact same length.