Speaker Construction

Hi Tlidd,

References: <49ivfl$
TT TT TT TT TT TT TT
if we are talking standard jensen-type dynamic drivers, then the 30"
size is already in the vicinity of the size of driver where the gain in
sensitivity by increasing the size is lost by the increase of cone
weight needed to make the cone behave in a reasonably rigid manner, and
it may even be above the optimum size, also because you have the problem
of getting enough magnetic field strength into the airgap.

This is why all replies seem to have focused on either multiple drivers
or horns or 'all of the above'. For a practical design, say 4 30"
drivers on a front horn with a 2:1 to 3:1 compression ratio might be a
workable solution. Efficiency would be some 5 to 10 percent (just a
guess), and powerhandling in burst and/or 'integrated programme' could
run as high as 2 kW. Radiated acoustic power would then be some 100 to
200 watts (peak), and you probably could build the thingy to fit
reasonably on a flatbed truck. The most difficult part of it would be to
get the cabinet rigid enough, carbon fiber might be an attractive
solution, just build the horn in that material and encase it in sand.

You would of course need custom designed speaker units, I don't think
the 30" units on the market are designed for front horn use, simply
because such designs as the one outlined about falls in the category of
near technical folly, and also they do in fact remind about weapons.

Construction of a 4' loudspeaker cone would be fairly close to the
impossible, simply because its inevitable breakup modes would be at
unpleasantly low frequencies, and even bass linearity would be very very
poor.

Kind regards

Peter Larsen


* Internet: , Copenhagen, Denmark *
* Fidonet: Peter Larsen@2:235/334.4 *
* Relaynet(tm): Address to Peter Larsen, route - * Conference Host for the Relaynet Amiga Conference *


---
?? RM 1.3 03104 ?? Internet: , Fidonet: Peter Larsen@2:235/334.4

Sounds a lot like a more modern implementation of an old French
pre-electronic design that used steam pressure for acoustic
output down in the sub 10 Hz area.

When was this beast at White Sands? I saw some of the electronic
transducers used to test missile components...these were multi KW
amplifiers and some huge voice coils. The coils didn't have
cones, they were bolted directly to whatever was to be vibrated.
[And on at least one occasion, a sheet of plywood for playing
XMAS carols but thats another story.]