Woodworking and DIY build planners
Planners for workshop builds: enter your sizes and stock, and get the counts, a cut list, a printable build sheet and, where it helps, files for a CNC router or laser.
Acoustic diffusers: skyline or QRD?
| Skyline (2D blocks) | QRD (1D wells) | |
|---|---|---|
| Looks like | A grid of square blocks of different heights | A row of slots of different depths between fins |
| Scatters sound | In two directions (up/down and left/right) | In one direction, across the wells |
| Built from | Square sticks (such as 2x2) cut to length, or an egg-crate of slotted strips | Fins and well bottoms from sheet material |
| Main work | Many short cuts and a lot of gluing | Fewer, longer parts; accurate well depths |
| Guide | Skyline diffuser plans | QRD diffuser design |
The acoustic diffuser calculator plans both from your panel size and stock: heights, counts, a cut list with kerf, a glue map and DXF files for the strips and fins.
Problems this solves
- "How many 2x2s do I need for a skyline diffuser?"
- Enter the panel size and stock; the cut list packs the pieces onto your stick length allowing for the saw kerf and spare.
- "What depth should the wells or blocks be?"
- It follows from the design frequency and the prime N; the QRD guide shows the formula and two examples.
- "Calculators give different frequencies for the same panel."
- There are two conventions in use. The calculator shows both, and the QRD guide explains the difference with numbers.
Real sizes, not nominal ones
Lumber is sold by nominal size: a "2x2" is about 1.5 in square. The planners here ask for the actual width you measured, allow for the saw kerf between cuts, and say how many sticks to buy, so the plan matches the wood on your bench.
Guides
- QRD diffuser design: well depths, width and frequency rangeThe quadratic residue sequence, well depth formula and frequency limits, worked through for N = 7 and N = 13.
- Skyline diffuser plans: from panel size to a cut listA worked 24 × 24 in skyline build: heights, counts, sticks to buy, glue map and build order.
Related categories
For metal work and full-size cutting templates, see sheet metal and fabrication; for printable templates and laser rotary work, see crafts and printables.