[ChrisCoaster]

Just thought I'd throw this out there - partially to punctuate the
endless Google Groups posts hocking knock-off handbags and Nike
merchandise - and to see if this idea might actually go somewhere(!)

I'm thinking about a speaker line, both a bookshelf and a
floorstanding model. Standard 8-16ohm impedance, current state of art
materials, with as low-resonance a cabinet as humanly possible.
Speaker would be a sealed unit, capable of handling anywhere from
50-200W.

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.

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.

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.

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. 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).

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!

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.

-CC

[UnsteadyKen]

ChrisCoaster said...

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.

It might work at very low frequencies less than 10 hz perhaps.

In the normal frequency range, 500hz for example if the cones were to
use the full 1 inch travel yet still produce an accurate representation
of the waveform presented to them they would have to accelerate and
decelerate at values approaching infinity or thereabouts thus implying
a cone with no mass would be required.


--
Ken O'Meara
http://www.btinternet.com/~unsteadyken/

[ChrisCoaster]

On Oct 30, 9:39*am, UnsteadyKen wrote:
ChrisCoaster said...

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.

It might work at very low frequencies less than 10 hz perhaps.

In the normal frequency range, 500hz for example if the cones were to
use the full 1 inch travel yet still produce an accurate representation
of the waveform presented to them they would have to accelerate and
decelerate at values approaching infinity or thereabouts thus implying
a cone with no mass would be required.

--
Ken O'Mearahttp://www.btinternet.com/~unsteadyken/
_____________

Of course, I didn't specify that the full 1 inch(or more!) of travel
might not be reached until you are achieving at least 70dB spls. I've
always believed, growing up, that the speaker that moves more air
yields more lifelike results.

-CC

[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

[David Nebenzahl]

On 10/30/2010 6:20 AM ChrisCoaster spake thus:

Just thought I'd throw this out there - partially to punctuate the
endless Google Groups posts hocking knock-off handbags and Nike
merchandise - and to see if this idea might actually go somewhere(!)

I'm thinking about a speaker line, both a bookshelf and a
floorstanding model. Standard 8-16ohm impedance, current state of art
materials, with as low-resonance a cabinet as humanly possible.
Speaker would be a sealed unit, capable of handling anywhere from
50-200W.

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.

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.

Heh; this reminds me of my own thinking as a kid fooling around with
building speakers[1] and thinking of how to make the "ultimate woofer".

So as absurd as this proposal seems to have been, it raises some
interesting questions (non-absurd, I trust). In particular, if one were
to try to design such an "ultimate woofer", what would be the main
limiting factors to powerful low-frequency response?

1. Cone size (area)
2. Cone compliance (maximum excursion)
3. Motor strength (voice coil size, power capacity, magnet size)
4. Cabinet size & shape
5. Other

(Hopefully Dick Pierce might be interested enough to answer this.)


[1] My first was an acoustic-suspension bookshelf system, built to plans
in Popular Electronics. I remember getting the 6" woofers, really cheap,
from McGee Radio in Kansas City. They're long gone, of course; anyone
else remember this company? They had an amazing selection of raw
speakers and all kinds of other electronic stuff.


--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)

[Arny Krueger]

"ChrisCoaster" wrote in message


I'm thinking about a speaker line, both a bookshelf and a
floorstanding model. Standard 8-16ohm impedance, current
state of art materials, with as low-resonance a cabinet
as humanly possible. Speaker would be a sealed unit,
capable of handling anywhere from 50-200W.

Check the Paradigm catalog for suitable alternatives.

The two key differences a

1. All drivers(2 in the bookshelf and 3 for the
floor-standing) would be in the same plane.

Which same plane?

Are you talking about the plane that the speaker driver chassis are mounted
on or the plane of the acoustic centers?



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.

If their travel is unprecidented, then it never ever existed. At this point
drivers are available with excursions that exceed any possible practical
need at home. IOW you are asking for something that not only has never been
done, but also serves no practical purpose.



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.

Why does the floor-stander need to be 3-way?

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.

If there is visible movement when the speaker is driven mildly, it would
appear to me that there is likely some design fault. Well designed speakers
move their cones as little as possible consistent with undistored output.

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).

This is a rediculous cosmetic-only requirement.

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!

The operative phrase would appear to be "no expertise". A knowlegable person
would simply not ask for what you are demanding.

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.

Structural stiffness as perceived by you would appear to be yet another
ill-advised cosmetic requirement.