Diaphragm experiments?

[OrthoFan]

The post string about playing modern audio equipment through Victrola horns made me wonder if anyone has tried using modern speaker materials, such as titanium, in place of the mica or aluminum diaphragms originally supplied?

For instance, I'm wondering how something like this would sound in place of the mica diaphragm originally fitted into the Victor Exhibition sound box (with proper gasketing, modifications to the needle-bar, etc.):


From: http://www.simplyspeakers.com/12diaphragms.htm

The price of these components would stop me dead, but I'm wondering about parts culled from junker/damaged speakers....

[JohnM]

I've been wondering what graphite fiber diaphragms would sound like in DD reproducers. All the characteristics of shellacked rice paper and none of the drawbacks (porosity, dimensional fluctuations due to humidity, etc.) Totally airtight. Also, paper soaked in polyethylene glycol (PEG) to polymerize it.

John M

[larryh]

John,

Where do you get this graphite paper? What is it used for?

Larry

[WDC]

Taking speaker diaphragm is a very neat idea. I had thought of that possibility too but never came by a speaker of the right size to tinker with.
I think these speaker with a large full metal diaphragm, surrounded by rubber could reproduce wonderful results. They are mostly used in small devices and provide an amazingly huge sound.



Now I am thinking of how to make a working air-tight rubber bearing by myself. Maybe that's easier than ripping one from a speaker.

Norman

[Brad]

I would wonder if the speaker material might be too compliant with the result being lower sound levels. The speaker is designed to move more air so it has to move back and forth further than the reproducer diaphragm would.

Just a thought.

[JohnM]

Unless you are talking Orthophonic and similar where the diaphragm is designed to move like a piston, most diaphragms are designed to be held rigidly and flex across the entire surface. Flexible surrounds would defeat this.

Here is a link to just one of a number of sources for carbon fiber I found on the internet: http://www.graphitestore.com/cat.asp/spcat_id/2

I still think polymerized paper is a viable alternative for DD and cylinder reproducers. What does a diaphragm need to be?
a) strong
b) dimensionally stable in varying conditions of temp and humidity
c) airtight
d) proper thickness/flexibility/'crispness'

By soaking paper in PEG (which is used by wood workers to stabilize green wood before working it so it will not split after drying) the paper remains paper, but takes on the added desirable characteristics of plastic (see a, b, c & d above). Polymerizing paper is the equivalent of Edison's original method of shellacking rice paper, but likely much superior due to the nature of modern materials.

John M

[OrthoFan]

Taking speaker diaphragm is a very neat idea. I had thought of that possibility too but never came by a speaker of the right size to tinker with.
I think these speaker with a large full metal diaphragm, surrounded by rubber could reproduce wonderful results. They are mostly used in small devices and provide an amazingly huge sound.



Now I am thinking of how to make a working air-tight rubber bearing by myself. Maybe that's easier than ripping one from a speaker.

Norman

The diaphragm in your photo does a better job of illustrating what I had in mind. I believe that these discs are made from Titanium. I have a small tube type speaker designed to be used with PCs and other audio devices which has identical diaphragms suspended in ultra-soft rubber tube gaskets on either side of the air chamber.



Though tiny, the speaker unit literally fills an average size room with stereo sound. The diaphragm, itself, is an extremely light weight rigid disk. When the volume is cranked up, you can see the entire disc plunge back and forth.

[larryh]

Any body recall off hand the thickness of the original diaphragm from edison? I had it somewhere but not sure where.