"Goofball_star_dot_etal" wrote in message
...
On Tue, 30 Sep 2003 18:47:46 -0400, "Bob Morein"
wrote:


"Goofball_star_dot_etal" wrote in message
...
On Mon, 29 Sep 2003 16:23:45 -0400, "Bob Morein"
wrote:

1. The woofer weighs more than the tweeter. Hence it responds slower
to
the
driving electrical signal.

One might take some notice if one wanted to throw them. This must be
one of the worst cases of a feral physicist technobabble.

You are loosing(tm) it Bob, IMO.

The wording is an attempt to avoid confusing the reader with moving mass,
resonant frequency, and Q.
Why don't you give it a shot? It could be better.


It is not just a case of dumbing down the wording for the confused
reader. I fail to see a simple relationship between mass and time
delay. If you were to increase just the mass of the moving parts of
an ideal driver, for a frequency well above resonance, the amplitude
of acceleration, velocity and displacement would all be reduced in
proportion to mass but the phase/time relationship between air
pressure and applied voltage would be the same. If you scale down a
driver in proportion to wavelength, a lot more than just the mass is
changed including the applied force, but again, well above resonance,
the applied force and therefore acceleration, is proportional to the
applied current ( or voltage for constant impedance) and the velocity
and displacement just follow along in proportion, ninety degrees
apart. (assuming a ideal rigid structure). I can see no increased
delay due to increased moving mass of drivers. Scaling can be a tricky
thing, you will note but the motion of "ideal" drivers is not. Maybe
you are thinking of something tricky but it came out dumb - "heavy
equals slow/late"

All correct, above. I was trying to give Sam, who was not aware that the
speed of sound in free space is independent of frequency, something to grab
on to. Doing that, while exhibiting the level of erudition we expect, is
for me an unsolved problem. So I decided to focus on the relationship
between resonant frequency and group delay, and resonant frequency, I
decided, was best represented by one constant in the equation, mass.

If you can think of a way to present more information to Sam, who has just
learned that c is a constant, it would be useful to all of us.
Give it another shot. I'd certainly add it to my repertoire of answers, as
the question will inevitably occur again.


There is also something dumb here too, we noted. . .

"Auditory research suggests that complex noises are not localized by
time delay. However, the ear can distinguish intra-aural time delays
as small as 6 microseconds. This suggests that while a time aligned
speaker may not help one better distinguish the position of a
violinist, it may help the listener distinguish the positions of
percussive noises or other transients."

How can you change "intra-aural time delays" by any identical change
to two identical speakers?

That's a good question. It's intuitively appealing to me that the ear would
better be able to localize an impulse if it actually looks like an impulse,
as opposed to what you and I both know comes out of a non time-aligned
system. And that's all there is. I have no testing, blind or otherwise, to
back it up. I do know I enjoy the hell out of a set of Spicas when they're
set up right.