[Patrick Turner]

Phil Allison wrote:


** See:

http://www.usenet-replayer.com/group...lectronic.html

My pic is in the second row down, on the far right.

It is an extreme close up.

Shows only 1 sq cm of the panel and reveals what is down the holes.

OK, I now see YOUR close up this when I go to replayer.

Before, only ONE photo appeared at
ABSE which I could see via my ISP, and it was the same pic
as at a source I quoted, and as I thought only 1 pic was posted as a
mystery pic,
I was not looking for a second one.

Your photo DOES show the fine mesh behind the 1.7mm stator holes,
and looks like a fine square weave material, maybe 0.1mm between
threads,
and traces of glue spread, thus the air flow is restricted through the
rear stator holes,
which will occur at LF resonances when the membrane becomes very
sensitive
with regard to movement vs input voltage.
I guess they cover the stator with glue, but the holes are free of glue,
then they
lay the fine nylon gauze material down over the lot, probably with a jig
to prevent the
gauze moving much and dragging glue to obstruct stator holes.
HF would pass through with very little attenuation if the holes have
open gauze.

I though about doing something very similar with material to the
speakers I am building,
and may proceed, but I have to coat the whole of the rear of the stator
panel with a suitable adhesive then
evenly press it down without smearing or spreading out the glue...some
expertise with each technique is needed.

The QuadESL63 acoustic damping methode reminds me of the "aperiodic"
loading used in dynamic
speakers where a number of cloth layers are stretched across a port in a
bass speaker
to damp resonant behaviour, so the box is acts somewhat between a ported
and closed condition.

I have a shirtload of other work before i can return to the building of
my own versions of home made ESL, using just a few parts which were
supplied by ER Audio.
I have a new membrane material and I have a new coating material which
gives gigaohms,
not just megohms of resistance,
so the membranes should not arc to stators, and will more likely act
with constant charge, not
constant voltage, which can give drift in charge density under dynamic
conditions.
I measured the resistance of the ER Audio coating and found it MUCH
lower than the coating
provided to me for my panels. Its a secret, so don't ask me what's in
it.
In the damp rainly Sydney weather the ER Audio coating could easily be
wiped off the membrane.
Maybe its detergent based; I have no idea exactly what's in it, but it
ain't like original Quad
coating which was/is/remains good.

I also want to make the midrange units a smaller length than 1.2M, maybe
only 450 long,
with closer stator spacing than the ERA panels, and also have a small
tweeter
of only a maybe 100mm long. I don't see much need to have such a long
line of tweeter,
and I think a more nearly point source ESL tweeter will give a better
treble response.

From what I heard at my Sydney friend's house, there is NO need to have
the mid/treble panels
located in the centre of a bass panel like ESL57. Its fine to have
a pass panel 1.2M high x 0.6M wide, divided into 5 strips of around
100mm wide each.
The mid and treble units can be on the inside edge of the bass panels,
and mirror pattern for L and R.

If one sits at 3.5M away from a treble strip that is 1.2M long, then
there are considerable
differences in the arrival times for different F, depending on
wavelengths,
very much like what you'd get if you have a line array of dynamics where
supposedly a single vertical wave front arrives.

My own tests of the ER Audio panel revealed a considerable beaminess
with treble,
and mid/treble varied a lot between say 1.5M above FL and 0.8M which is
about the
seated-in-lounge height.

Patrick Turner.












....... Phil