I went back and forth with Brian a bit on the cutout for the SP1-4K since I was cutting without the amp in hand.
Here's a quote from him about the HT line:
The plate is 3mm thick and the knobs protrude another 15mm.
So 3mm + gasket tape should make the flange flush. I went with .25" to sink it a little more. I figure the 15mm knobs could be replaced with something shorter, while still leaving 1/2" for screws so I can lay the cabinet on the amp side without bumping anything.
The plate amp has a 1/2 radius on the corners of the flange, so be sure to consider the radius of the bit overall if you want a tight fit. The radius of a rabbet bit that cuts 7/16ths may be larger than 1/2 with a common sized bearing.
When I get my amps Tuesday I'll share some pictures of the fit and the dimensions of my cutouts. I added a little breathing room to the dimensions from the SP drawings.
It would be easy to make a template on the CNC for guided cuts.
Fortunately the screw holes on the SP amp are near the edge, so there's some wiggle room
Originally Posted by dsl1
I believe used a 1/4" depth on the rabbet. He can confirm.
Yes, that would work or you could do your cutout and use a 7/16" rabbet bit.