The Talking Machine Forum — For All Antique Phonographs & Recordings

Finally located and purchased an Edison automatic
recorder. It was made up from various parts
starting with a standard speaker body that someone filed the top flat on. As such, it was
"pre-butchered" and will work fine on my later
carriage that has the pin.

It is now equipped with a mica diaphragm.
Later on sometime I would like to try using a
glass diaphragm. The only glass diaphragms
currently available that I know of are Norman's
and those are .2 mm thick. That comes to a hefty
.008 inch thickness, which I personally think is
way too thick to do much good.

In the old book "The Phonograph and how to use it", they mention several thicknesses of glass
diaphragms going clear down to about .002 inch
thick as I recall.

All of my recording experiments to date have been done using .002 inch thick mica on the
later Edison "home" recorders.

My question is this: Where are the thin glass
diaphragms? Are there any around?
Or is .008 inch thick basically the only game in town as far as glass diaphragms to use
in an automatic recorder?

Thanks, Chuck

It has been several years, however, I seem to recall that I purchased one from our own Wyatt aka MicaMonster and I purchased the linkage attachment element (not sure what it is called) from George Voelema (sp? ). I could be totally wrong on both accounts, but that is my story, and for now, I am stickin' with it!

Here is a link to buy a glass diaphragm made by Norman.

http://www.phono-phixer.com/glassd.html

Thanks for those references.
No mention is made about the thickness.
The last I heard was that Norman's glass
diaphragms are 0.2 millimeters thick.

That converts to a hefty .007874 inches thick!

From my way of looking at things, this is way
too thick to be very sensitive when used in a
recorder. Sure, it will record some sound.

But it certainly will not be as sensitive as
a thinner one would be. I am not sure what the
thinnest ones ever made were, but I seem to
recall the book "The phonograph and how to use it" mentions a whole series of available
"glasses" to use in different recording situations. I seem to recall seeing mention of
much thinner ones than .0078 inches.

More like .005, and on down to .002

Not sure if they ever got clear down that far
to .002, but even .004 would be half-again
as thin as these hefty modern .008 thick ones.

Does anybody have any glass diaphragms around
at all that they could measure the thickness
of so we could get the ball rolling on this
discussion?

As far as the recording experiments that I have
done, I have a very strong hunch that it's
certainly no accident that the .002 inch thick
mica gives such good results.

How could one possibly expect decent results from such a thick glass as .0078 inches?

Chuck

Edison used microscope glass. Today, minimum thickness is about 0.003 inches. I am sure it cracks much to easy.