[Peter Larsen[_3_]]

ChrisCoaster wrote:

The two key differences a

1. All drivers(2 in the bookshelf and 3 for the floor-standing) would
be in the same plane. That is, the mid and hf elements would be set
back so as to be "in lne" with the resting position of the woofer.
This is not new, and many mfgs have done it for 20 years or more.

And lo and behold, it actually is a poorer design than having them all
integrated in the same flat surface because of the additional diffraction
edges and the strange multivariable baffle diffraction steps you end up
with.

2.(the big one!) - The woofer - and the midrange in the case of the
floor-standing, would have a range of travel unprecedented for their
size.

Dick said a lot of what can be said. However look at the "known good"
loudspeakers, those are in my experience characterized by minimizing the
excursion via a large effient area. This because it is easier to get a
suspension quasi linear within a small range than within a large range.

I'm proposing a 6" woofer and 1"dome tweeter for the bookshelf, and a
7"woofer, 3"mid, and same 1"dome tweeter for the floor model.

Bass unit size in itself needs to be seen in the context of box size,
intended bandwidth and obtainable efficiency.

I'm talking about both woofers having at least a 1" high-profile
butyl- rubber surround that would allow visible movement even when
driven mildly.

It is all about displacement volume.

The midrange might also be visibly moved, especially
on tracks with strong transient drums(think early-to-mid era Genesis
or just about anything from LZ).

Depends on what you call midrange.

Of course an area in which I have no expertise would have to be
advanced - and that is dampening. For a speaker like this the cones
might end up ringing like a bell!

Your vision of a loudspeaker cone is too simple, rigid cones are generally
more of a problem than of a solution because of exactly that problem. You do
not get a good directional diagram without the cone decoupling its outer
area when reproducing high frequencies, whatever that is in the context of
its working range. If you insist on using loudspeaker units only in their
piston range you end up with a 10 way system, ie. with 9 crossover-points
you need to get "just rightø".

My theory is that small rigid cones with high excursion move as much
air as effectively as a huge cone with less excursion and perhaps not
as structurally stiff.

Yes, that is a good "volume displacement" understanding, but a small cone
with little or hardly any excursion coupled via a horn has both advantages,
and then quite a few other problems.

It is always a matter of multiple tradeoff, and the art of the designer is
where to place them. The perfect loudspeaker has zero area, since area is
problematic, and zero excursion since excursion is problematic, but with
excursion and area both approaching zero the sound output does likewise.

-CC

Kind regards

Peter Larsen