"Arny Krueger" wrote in message
...
"Robert Morein" wrote in message

"dave weil" wrote in message
...
On Mon, 13 Oct 2003 01:06:34 -0400, "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 some examples of loudspeaker projects that appear to be
competently
designed:

http://www.geocities.com/john_wr2000/mini2/mini2.htm

http://www.kaiaudio.com/diy2001/kaiopen.html

I think that the interesting thing about this is that he has
measurements showing a change in measured performance after break-in
of drivers. There are some around here who claim that it's only a
case of "user break-in".

As far as I know, it's an accepted requirement that in order to
measure stable T-S parameters for a woofer, the woofer must be broken
in first.

The usual mistatements about other people's position noted.

There's no doubt that drivers change their technical properties in
extended
storage, and that those properties change again when the driver is
re-used.
The controversy is over how long it takes to properly break-in a driver.
The
usual technical answer is "a minute or less of heavy use".

http://www.kaiaudio.com/diy2001/kaiopen.html

fails to address the situation by failing to show results for a brief
break-in. However the stated "several hours" is brief by the standard of
most break-in anecdotes, which generally mention running the equipment for
days.

I concur with a period of several hours. That is sufficient to mechanically
alter the surround material.

As far as breaking in a tweeter, "microfriction" is a concern in the
design of modern mid frequency drivers. It's now believed by many
that the surrounds have friction properties as well as those
characterized by loss. In other words, the driver can stick
microscopically as the cone moves. Proper choice of surround and
suspension materials minimizes microfriction. Here as well, breakin
may be useful.

Interestingly enough searching google for microfriction & speaker as well
as
microfriction & tweeter comes up empty.

Microfriction is usually associated with sliding supports which speakers
generally don't have.

I did the Google search, and obtained the same result.
My information is a stated concern of KEF, who have done proprietary
research.