Bass reflex standmounts 10.3 / 10P

I have no idea what chrisb and Scottmoose are on about, but anyway - totally unsuitable enclosure damping foam underlay has now been removed. Listening test ongoing now. Early thoughts are that I have a crisper treble and smoother lower-midrange. Might be all psychological of course, but I reckon they sound 'better'.

Won't make the same mistake when building the Pensils...
 
Thanks Dave, I asked because the equivalent br box for the alpair 12p did have this dimension fixed (its not on the drawing but i remember it being stated in a thread) I remembered this because it was the same distance as the driver centre from the top of the cabinet, would this be coincidence, aesthetic or functional?
 
I am building these to try them out before going forward with some Pensils for my A10PeN. A quick question, i have some square terminal cups i plan to install. They are not lined with foam to around the edge. Is it necessary to have this does the approx 1cm wide, flat plastic surface create enough of a seal?