Altec 604 D Enclosures

[charly1944]

Hi everybody,
I received from GPA my pair of 604 D.They remag. them and changed the LF cones.I also bought from them their N1600-16 crossover.After a pretty long breaking in period,i tried them at a friend's place.He has got a pair of 604 E with original cones ,a pair of "interesting" enclosures.So we could compare the two pairs of speakers in the same room and the same enclosures using the GPA crossover.The first conclusion is that the 604 D reconed by GPA sounded much better than the 604E with their original cones.Our best guess is his speakers probably need a remag.and may be a change of surround to perform optimally.The second obvious conclusion is that GPA did a very good job and that people should not hesitate sending their Altec to GPA for reconing.
Now come my questions regarding the enclosures.My friend has a pair of BR enclosures with the following external dimensions in feet :Height 3.05;Width 2.13;Depth 1.48.
Internal volume is about 11,3 cubic ft (from which one has probably to deduct the volume of the driver).The cabinets are bottom vented and the vents are actually two rectangles(1.0x1.5 feet) cut in the bottom of the enclosures and facing the floor.The 4 feet are 2 inches high.The walls are made of pretty thin(O.6 inch) and light plywood(Density about 0.5 when Baltic plywood is 0.7).No braces.The only internal damping consist of thin felt covering the internal walls. Those speakers are driven by high quality SE 300 B amplifiers.I was expecting from those speakers a lot of disturbing vibrations but actually they sounded pretty good and the only limit i could find was that i would have preferred the bass to go lower.So should i simply copy those light,inexpensive ,easy to built enclosures for my 604 D or should i try to improve them and in this case how?Charly 1944