"Joseph Oberlander" wrote in message
ink.net
Robert Morein wrote:
"Arny Krueger" wrote in message
...
There's been so much discussion of a technically-incompetent small
loudspeaker design on RAO lately, I thought it might be helpful to
post
http://users.ece.gatech.edu/~mleach/labsp/
If the economics weren't so bad, some of these designs would be an
important addition to the existing choices.
This one design I left in above looks promising, though I like sealed
box designs better myself.
I was reading articles on other pages and ran across an article
stating that it was possible to design a speaker with no crossover
required.
I always thought you had to use a crossover to get the best results?
As a rule you do, but there are a number of end-runs.
(1) Use a lot of really tiny speakers that can act as tweeters, but when
massed, have possibly useful low frequency response. Ironically done right,
you end up with frequency-sensitive networks in the system design, but they
aren't exactly crossovers.
(2) Use speaker driver(s) that are effectively dual mode. Mode one is
piston mode. Small drivers can work this way up to a couple of KHz. Mode two
is "break up" mode. In break-up mode only small portions of the diaphragm
radiate the highs. Think of the time-dishonored "whizzer cone" as an
example of cone break-up implemented with a big figurative hammer. One tough
trick is getting full-range response because even in break-up mode, most
drivers want to roll-off above 10-12 KHz. Another tough trick is getting
smooth response through the transition region. For these reasons, you again
often end up with frequency-sensitive networks in the system design, but
they aren't exactly crossovers.
(3) Use drivers whose acoustical response just naturally rolls-off to
perform the function of crossovers. Easier to do with woofers than tweeters.
(4) Use a driver that can actually naturally seem to be able to cover the
full audio range. Ironically, the best examples of these often end up having
woofers or tweeters added to them at a future point in their development.
They again often end up with frequency-sensitive networks in their system
design, but again these networks aren't exactly crossovers.