Dear HDbrbuilder,
thank you for your fast response to my question. To avoid misunderstandings on my side I will tell you in my words what I will do next to follow your advice and come close to the original.
All mesurements are in cm. Material will be multplex birke.
I will take a panel 1.9 cm strong; 25cm x79.5cm where I will saw the holes for the horns. Then I nail or mount thick panel approx. 4cm strong 25cm x 10 cm. Doing so I can fix this whole contruction to your mentioned vertically mounted inside glue blocks(these are still in the cabinet).
Later I can cover the construction with in grille cloth.
Could you please tell me if this is the right understanding of your advice. If I do so the complet cabint is closed and the front panel will be approx. 2,5 cm behind the beginning of bottom panel of the cabinet an 1 cm behind the top panel repectivly.
Due to my listenig experinece with the actual construction and on traces or shadows on the top and bottom panels of the cabinet I assume this could be right.
You mentiod in your last sentence the diferences in "B" and "C" style cabinets. Do you have any experience to add these riser to my construction?
Thank anyone for help in advance. If a photo is someware availble could be in addition a good help for me.
Jörg from Germany