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Online PRD calculator:
Calculate a Two-Dimensional Primitive Root Diffuser (Skyline)
A 23x12 grid can be bult using prime 277 and primitive root 5. Here's a suggestion with every parameter quantized to inches (2.54cm=1 inch):
Speed of sound: 343 m/s
Quantize well heights within: 2.54 cm
Lowest frequency: 964.5669291 Hz
Highest frequency: 3375.9842351 Hz
Prime number P: 277
Primitive root of P: 5
# columns: 23
# rows: 12
24*46 inch grid, 2" widths and 1" depth quantization(7 inches total depth).
The depths are listed as:
2.54 cm: 40
5.08 cm: 39
7.62 cm: 40
10.16 cm: 40
12.7 cm: 39
15.24 cm: 40
17.78 cm: 19
Which is 1/2/3/4 etc inches written in centimeters.
Here's a post with more details on the parameters for the calculator.