Ron(UK) wrote in message
...
N Cook wrote:

If you took a cone from a 12 inch and a 15 inch and laid them face down on
a
surface. Then a flat plate on the cylinder extension of the 12 inch and
then
some weights on that, but not enough to cause it to collapse.
Then add the same plate and weights to the 15 inch and before the cone
would
collapse by compression or radial buckling, would not the larger one be
more
likely to start to fail by the central section twisting and then
collapse.
Less torsional stiffness is probably the term I'm looking for.

I don't really understand where you're coming from, the only 'weight' on
a speaker cone is the voice coil assembly and dust cover and they weigh
very little, even in a high power speaker. compared to PA speakers,
guitar amp speakers are often deliberately made with reduced cone
stiffness so that they 'trash out' at lower volumes.

In the back of my mind, I do recall seeing a photo of a speaker cone,
face down, with a chap standing on the voice coil former to demonstrate
the strength of the cone assy. I don't remember which company it was.

Most pro speakers have very rigid cone structures, it`s pretty uncommon
to find a professional speaker failure that is attributable to
mechanical damage during use, even over excursion is fairly rare - tho
dj`s do try their hardest.

Almost all pro speaker burnouts are due to being driven with amplifiers
of insufficient headroom,[1] or some external failure i.e. Bad switch
on sequence etc.

There was once a company called Baker who made probably the worse
speakers in the world, the skinny cast alloy baskets would crack,
dumping the puny magnet in the bottom of the cabinet - happily long in
the past.

[1] That statement may lead to flameage

Ron(UK)

This was not in-use damage but from storing in a damp garage for some years.
It went in perfectly ok and came out with amp working but speaker sounding
like the amp was clipping. The amp will drive an external speaker fine and
another amp gives horrible noise through this speaker.
So damage due to transporting from (ot to) the garage face-down or more
likely something to do with damp distorting the cone or maybe distorting it
now its been indoors for a few weeks, drying out.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/