rob wrote:Here's one for the PA guys out there!
Well, since we live in the age of cheap amp power and high power/high efficiency drivers, PA bass horns aren't that popular any more. Since PA horns should be transportable, their dimensions and therefore their performance gains are rather limited. It is easily possible to achieve similar or better results with an array of small boxes ("small" compared to a horn, of course). And since we live in the age of cheap digital controllers, use of an array also allows for beam shaping.
The problem with high power high efficiency drivers in horns is the excursion limit. When operated at "nominal power", modern drivers will quickly rip their diaphragms apart.
Notable exceptions may be the EV MTL4 and the Intersonic BT-7, but both systems aren't really popular either. Both systems are rather compact....and expensive. However, they can't really be compared to the usual bass horns. The BT-7 uses a special driver (the servodrive, or "motor bass"). And the MTL4 isn't really a horn - the idea behind the design is to cram more drivers into the same space without getting array effects.
rob wrote:If its the individual dimensions, is there a way of,say, adding some length to the horn(s) to combine the individual horn mouths into a single large mouth.
As far as I understand, you wish to design something like the JBL 1530 (
http://members.aol.com/xxbase80a/rutsche.1.15/box.html), operated sidewards? In that case, it is possible to simply eliminate the divinding walls between the indivdual boxes, like in the JBL 1520 (
http://members.aol.com/xxbase80a/doppelrutsche.2.15/box.html).
However, even with the dividing wall removed, the box will still be quite heavy. Even in the case of the 1530, simple "lightweigt constructions" often rattle or resonate in an unwanted way. Making the construction wider and leaving out the walls between the individual sections makes the whole thing more floppy, requiring additional efforts to maintain it's stiffness. In other words, it's still quite an amount of wood and woodwork! You might end up finding out that it's cheaper to ditch/sell the Fostex drivers and invest into a more suitable driver for your needs, which will work in a "normal", much cheaper enclosure.
BTW,
Judd wrote:Look up McBean's horn calculator, i'm not sure if it will do back loaded horns though.
that would be
http://mywebsite.bigpond.com/dmcbean/.
Best regards, Klaus