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Old 11th September 2013 | Show parent
  #113
Gear Maniac
 
robertopisa's Avatar
 

Surprisingly, they are also effective as absorbers in the range 100-200Hz, maybe because they vibrate.

Here are the files with the AutoCAD coordinates in case you want to use a CNC machine.

https://mega.co.nz/#!No9yDSyR!VncMVF...GmvKzEyF7q1YgE

Please note that, although RPG BAD are patented, the binary hole pattern is free since it already appeared in Number Theory in Science and Communication: With Applications in Cryptography, Physics, Digital Information, Computing... by Manfred Schroeder (first edition is 1984).

I am using these, built using 2mm PVC on a wood frame: