[Patrick Turner]

Chris Hornbeck wrote:

On Thu, 31 May 2007 01:38:36 GMT, Patrick Turner
wrote:

I am investigating alternative coatings and techniques for the membrane
and stators.

I am back at square one with these speakers.

My, but you're game. For a geezer even older than me,
that's really inspiring. Maybe I'll get more energetic
in a few years... or not.

I have done little that earns me mountains of dollars,
and a done a lot just for the experience.

I must have entered a hundred races, and won only one or two,
but cherished being there even when i lost.

So there is nothing much more to lose if I see my customer right by
getting
him the speakers he ordered.



You'll doubtless be investigating spacing and tensioning,
but I urge you be open-minded about diaphragm specific
resistance.

I have a weak premonition that, after tensioning issues
are resolved, over-large time constants across the
diaphragm will be more obvious. The factory values
are orders of magnitude larger than some successful
designs.

Well indeed. The best coatings appear to take longer to charge up,
and don't arc when a membrane slaps against a stator....


The line of thinking goes more or less: small variations
in localized diaphragm movement both cause dissipative
losses and provide local hot spots for stator contact.

I have tried to avoid the membrane getting too close to a stator.
Quad ESL57 did this with their 2mm thick PVC stators with highly
conductive electrode
painted on the outside only of the PVC stator plate.

You've dismissed this before, but maybe it'll be more
interesting at the current state of the project. Perhaps
a way to observe results (diaphragm homogeneity) using a
strobe light can be found. This is workable for sufficiently
"open" or porous stators, but not for every design.

It will be a fortnight before I proceed to re-do this first panel yet
again,
or begin with all new materials throughout.

The customer sees my difficulties, and understands what is on offer,
and I have my standards which are as high as his expectations.

We really only wanted performance equal to the Quad ESL57 in good
condition;
its a 50 year old design, and you'd think ERA could easily duplicate
that.

Patrick Turner.

All good fortune, and much thanks, as always,

Chris Hornbeck