need quick help with A10.3 info !

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Hi, I'm about to cut into the front baffle but the drawings on the downloadable pdf for the Alpair 10.3 are nearly useless - they are so small and fuzzy I can't read the data from them. Anybody have proper and reliable dimensions for the cut outs needed for this driver (with bezel) into 17.5mm birch plywood ?
 
As Jeff says, you could just zoom in on the PDF drawing, but short answer is with bezel:
OD = 165mm
ID = 139mm

rebate depth ( Z)= 11.8 ( test to allow for minor compression of molded gasket)

without bezel:

OD = 160mm
ID = 139mm

rebate depth = 10.5mm


If you're planning on CNC routing of the rebates, I'd suggest allowing at least and extra .5mm dia on both through hole and recess for ease of installation / removal of drivers - if they're too tight and you need to force them to fit, you're asking for trouble - and of course if you ever need to remove the driver :(
 
I had a bash at some routing. It's been a year since I built the Big'un speaker and as a result it took hours to locate the relevant tools :redhot:

Still, I managed to find it all. First image you see the set-up, with a drill bit sticking out as the centre-pin which pokes through a strategically placed hole in the scrap wood screwed to the base of my router to ensure the right diameter circle. I erred on the generous size for the outer circle to get a diameter of order 168mm and a rebate depth of a hair over 12mm. The inner circle, the cut-out, is something of worry because if you make this generous there's a risk of not leaving enough land for the mounting screws. The Alpair drivers have very little tolerance in this regard. I opted to under-size slightly at around 134mm diameter. I'll then manually enlarge the cut-out to suit the plastic frame supports. My router doesn't go through the total baffle thickness so I had to turn the pieces over and route from the back to complete the cut-out. To get the front and back cut-outs to line up you need to drill a perpendicular hole in the centre for the centre-pin. I managed to do a good job of this on one baffle, but the other was out (I really do need a drill press).

And the chamfers at the backside are done too.
 

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Some progress has been made on the porta-bench in my driveway :cool:

A couple of holey braces were positioned starting just below the driver cut-out where I want to stiffen things the most. Both braces are vertical, one front-to-back and the other side-to-side.

I then installed a number of other criss-cross braces from left over 2" wide 'sticks'. In particular I wanted to brace the port opening against the back of the box since the open edge is not supported otherwise.

I installed some thick felt lining around the inside of the top part of the box to tame high frequency reflections.

The driver has been dry-fitted to test the opening dimensions.

I'm probably about half way through the work effort now. It needs A LOT of tidying up before it looks presentable.
 

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