QRD diffuser designer
Well depths for a quadratic residue (Schroeder) diffuser.
Hz
cm
Sets the upper frequency limit.
Deepest well
19.61cm
Upper frequency limit
3432Hz
Period width
35cm
| Well | n² mod N | Depth |
|---|---|---|
| 1 | 0 | 0 cm |
| 2 | 1 | 4.903 cm |
| 3 | 4 | 19.61 cm |
| 4 | 2 | 9.806 cm |
| 5 | 2 | 9.806 cm |
| 6 | 4 | 19.61 cm |
| 7 | 1 | 4.903 cm |
Depths are measured from the top of the diffuser to the bottom of each well. Dividers between wells should be thin and rigid. This is the classic Schroeder design; verify with a simulation for critical installations.
How it works
A QRD scatters sound in many directions using wells whose depths follow a number sequence. The design frequency sets the deepest well; the well width limits the highest frequency that is diffused. N must be prime.
Formulas
- d_n = ( n² mod N ) · λ₀ / (2N)
- f_max ≈ c / (2 · w)
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