Just another more trial with modified Exhibition...

[Inigo]

Yes... I've once tried a piece of small hard thin corrugated cardboard, which when touched with the finger point emitted a promising sound. But it didn't have enough treble nor bass... Of course it compared with the original mica favourably, but the sound seemed quite muffled, not as brilliant as mica or glass.
Your ideas of trial with thinned wood... This likely would have the stiffness to transmit treble, and at the same time the flexibility to transmit bass...
The photo of diaphragms I've made and tried it's in this thread
viewtopic.php?p=349518#p349518
The black diaphragms on the last photo there, are the ones made from that thin cardboard, one for the exhibition and the larger one was tried on the HMV no4. They looked nice, but sounded somewhat muffled... no high treble.

[CarlosV]

Wyatt Markus makes a diaphragm out of modern dollar bills, which are not paper but a kind of a fiber. The one made for Edison diamond discs is excellent, much better than the original, and the one for the Vitor/HMV 4 sounds slightly better than the mica, but it has the drawback of looking ugly, so I decided to keep the original mica. There are some English makers that also made diaphragms out of fiber, Lenthal being one of them, but when I played it I did not notice any improvement over a standard mica soundbox, which may be due to aging: the compound utilized to increase the rigidity of the fiber probably degraded over the years, like the Edison diamond disc. In summary, Iñigo, my suggestion is to direct your creativity to modern fiber materials, it may be a good alternative to metals.

[Inigo]

Ha! Thanks for the tips and suggestions... I'll see what can I use for the next experiments.
By the moment in the 'To Try' list there is,

- Pure aluminium
- Thin wood
- Treated fiber (varnished in shellac?)
- Bank note paper (supposedly in layers glued with shellac?)
There was also another candidate, ironed or pressed Styrofoam, very promising, judging by the good sound of a food tray provided with a needle, attached to the corner (the modern poor man's Gramophone)... Did you ever try that? It sounds amazingly!

An interesting list...

My references for sound are the original mica, or perhaps better the thin glass (which sounds similar but with certain added clarity and crispness), and the Absolute Top Reference is the sound of HMV 5a/b soundbox. This last is a high goal... difficult to achieve.

[Hoodoo]

Greetings,
I mounted my “wood-look” diaphragm in one of my. Columbia reproducers and played a record , once with the non-mica and once with the standard mica diaphragm on a small, tabletop Columbia machine.
Using a free sonic tools app, I positioned my iphone in front of the gramophone to sample the sound produced.
I used the same bamboo needle for both samples, sharpened between plays. See graphs below.
Ignore the red bars, as they are just the sound of the room after the record had finished (higher decibels than expected, given that I was in a quiet room and the furnace was not running!).
The dark blue/green bars show the peak hold, the maximum that the various bars/frequencies went to during the playing of the record (12 per octave).
There is not much difference between the two diaphragms.

[jamiegramo]

How did they sound to your ear?

[Hoodoo]

The mica was a bit brighter, perhaps, and the non-mica a bit mellower, but they were actually quite similar.
I should do a blind listening test, get a friend to swap out the reproducers so I can rate the sound without any preconceived bias. I have made a plastic diaphragm and an aluminum one for Exhibition reproducers (I have half a dozen, or so), so those, plus a stock mica one would make for a good shootout.
Next week, perhaps.