This is my implementation of John 'Zaph' Kutke's W3-871S design with notch filter. I was particularly
captured by John's design when I first came across it, and after reading further positive things about this cheap yet astounding little fullrange
driver, I felt it was time to build some monitors.
The design was adapted slightly to account for 18mm wood vs 3/4" available in the U.S and pieced together slightly differently.
A quick standing waves calculation
shows there are no fundamental problems. The internal net volume is 2.86 litres or 0.101 cuft. and the baffle width is 147mm or ~5.75" as
specified in John's design.
I had some off cuts of standard 7-ply plywood, and decided to use salvaged rear connector plates
to give easy access to the notch filter should it be required.