Post by Greg CameronPost by Peter LarsenThe 4520 is only economical if used up to 800 Hz so that you
can skip also getting low midrange boxes, not all 15" units
may qualify for that task and not all currently available
midrange horns and drivers qualify.
Not a particularly good sounding box,
Depends on build quality, on proper placement of damping and on array
construction, a pair should be on their side so that the 15" units form
a vertical column, put them side by side and midrange will suffer from
combfiltering due to interference patterns.
Post by Greg Cameronespecially if you cross it up that high,
Depends on the unit you put in it, it had better not have a midrange
problem, it is however quite correct that it is better to cross it over
at 250 Hz. In the context I think it will do just fine.
Post by Greg Cameronthough it may be loud.
Yerp, and the requirement was to fill a standard school gymnasium with
sound, 4 of those, 2 each side, and suitable tops will do that
reasonably.
Post by Greg CameronI for one am glad it's dead and buried ;-)
There are smaller boxes around, they just need more amplifier power.
Some of the time that will be a better choice.
Post by Greg CameronAlso a beast to drag around.
Technique, technique, but it requires two persons to lift them, yes.
Post by Greg CameronI hear they're still popular in the reggae circles.
So it appears from the carneval pictures from London.
Post by Greg CameronWhat year did JBL stop making those anyway?
Mid to late 1970's, JBL's own version was btw. not a good build and did
not sound as good as they could, wood is expensive to haul around also
for the box builder. The horn design is however in my opinion good, it
just need to be built well. A sandwich board with MDF center and plywood
outer layers could be a good idea. Of course, it did take an array of 4
of them to compete with a large Duelund horn in terms of downwards
range, but that was because of horn length issues.
What did them in was mostly SPL demands, the Martin 215 bin put twice as
many 2205s in the same array area with slightly higher efficiency and
was safer to stack, but did not have the same downwards range.
Kind regards
Peter Larsen
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