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I have a few older Edison Model C reproducers that have mica diaphragms that I would like to rebuild. Questions:

What is the best way to secure the center eyelet to the diaphragm? Not sure if glue is generally used, or something else.

Are replacement Model C mica diaphragms available?

I've noticed that some of the early side-arm reproducers I've seen have copper diaphragms, and assume that this is not correct, and the original mica ones were replaced with copper at some point. Am I right, or did Edison start using copper diaphragms back when side arm reproducers were still being produced? Does anyone know about when Edison changed from mica to the copper ones?

Thanks.

Although many collectors believe that Model C reproducers with adjusting arms are among the earliest variations, it's not necessarily true. Steve Medved wrote an article on the Model C Reproducer, which appeared in the September 2015 issue of the APS magazine, and he noted that these reproducers were assembled as needed into 1907.

Steve also noted that the change from mica to copper diaphragms occurred in Sept. 1906, so the combination of an adjusting arm with a copper diaphragm is not out of the question. The difference between the early copper diaphragm and the later copper diaphragm is also described.

If your Model C reproducer is numbered above 601353, it's quite likely to be all original.

This information was obtained by using the new "Search" feature on the APS website under the "Library" tab.

George P.

Thanks, George. I didn't know that the changeover from mica to copper occurred so late. The majority of the Model C reproducers that I have seen have copper diaphragms. I assume that many of these Model C reproducers have had the diaphragms changed from mica to copper either when they were rebuilt, or around the time when the changeover occurred. The copper ones do sound much better, I think.

You can get some wonderful sound from a mica diaphragm C if it's in good shape. Two years ago or so I had the privilege of rebuilding a like-new 1904 Edison Home Model A for the descendants of its original owners. It had a nicer sound than I've heard out of a copper diaphragm, and I think it's because the machine was in very good condition and had not delaminated. This left the compliance original & everything fully functioning.

As for an adhesive burnt shellac works nicely. Take a drop of undiluted shellac, wave a flame over, burn the alcohol. This is tricky though and you may like super-glue better.

VanEpsFan1914 wrote: Wed Mar 31, 2021 9:51 am You can get some wonderful sound from a mica diaphragm C if it's in good shape. Two years ago or so I had the privilege of rebuilding a like-new 1904 Edison Home Model A for the descendants of its original owners. It had a nicer sound than I've heard out of a copper diaphragm, and I think it's because the machine was in very good condition and had not delaminated. This left the compliance original & everything fully functioning.

As for an adhesive burnt shellac works nicely. Take a drop of undiluted shellac, wave a flame over, burn the alcohol. This is tricky though and you may like super-glue better.

Thank you. Super-glue sounds closer to my meager skill level. I appreciate the help.

I am a retired dentist. One of the first things you learn in dental school is how to handle waxes. Dentist use various waxes for a number of things. The technique is fairly simple to learn. Most of the instructions I find online, however, aren't very good. Here is the way dentists do it:

Purchase a No. 7 wax spatula from a dental supply house or online. They are easy to find. The spatula has a small end and a large end.

You will need some sort of open flame. A bunsen burner works best. I would imagine an alcohol lamp would too. Or maybe even a candle.

1. Take the small end of the spatula and hold it in the flame for a few seconds.
2. Press the spatula into the side of the stick of wax, or shellac or whatever. If the spatula is the correct temperature, it should sink immediately into the wax and pick up some of it.
3. Put the end of the spatula back into the flame for a second or so. This is a very important step. It remelts the wax to the proper temperature so it will flow.
4. Touch the end of the spatula to wherever you wish the wax to go. It should flow right onto the surface. If necessary, reheat the spatula slightly and put it back into the wax you just deposited. You can actually move it around and paint with it.

You can do the same thing with the large end of the spatula if you wish. This technique is really simple to use once you get the hang of it. The key is to get the tip of the spatula to the right temperature to pick up the wax and then the wax to the right temperature when you reheat it. After a few times you will get a feel for it. It works great for repairing reproducers.

Harry

Thanks for the precise instructions!