Little Thorens Gramophone

Discussions on Talking Machines of British or European Manufacture
jboger
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Re: Little Thorens Gramophone

Post by jboger »

mrrgstuff:

Interesting to watch you dismantle your reproducer. May I add my two-cents worth? I would re-use the mica; it's totally salvageable not to mention original to the soundbox. You surmised that the inner brown paper is original. I believe it is. I have another Continental reproducer (Swiss?) that had such a textured piece of brown paper inserted inside. It serves no purpose other than to be decorative, so one doesn't see the bare metal behind the mica. My paper had become so deteriorated and brittle that it simply disintegrated.

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mrrgstuff
Victor O
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Re: Little Thorens Gramophone

Post by mrrgstuff »

jboger wrote: Mon Mar 29, 2021 9:06 am mrrgstuff:

Interesting to watch you dismantle your reproducer. May I add my two-cents worth? I would re-use the mica; it's totally salvageable not to mention original to the soundbox. You surmised that the inner brown paper is original. I believe it is. I have another Continental reproducer (Swiss?) that had such a textured piece of brown paper inserted inside. It serves no purpose other than to be decorative, so one doesn't see the bare metal behind the mica. My paper had become so deteriorated and brittle that it simply disintegrated.
Thanks for watching the video :D

The mica is indeed in better condition than expected, although has a bit of a split at one point and a portion of delamination. I have already made a replacement plastic one (next video) and cleaned up the mica one too. I certainly plan to try the plastic one, but may also put the mica one back in for comparison.
The wax on the outside and the modifications to the back may have fooled me into thinking this was less original than it actually appears to be.
I think I have ruined the backing paper :( but should be able to replace, its nothing very special.
Just deciding now what to do with the main body. The dull grey effect I think is oxidisation. The metal I think is spelter or pewter or some other pot metal like alloy. The clean metal is a sort of straw colour, not brass.
Thanks
mrrgstuff

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mrrgstuff
Victor O
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Re: Little Thorens Gramophone

Post by mrrgstuff »

I've now made a replacement diaphragm, but not yet fitted it. It seems to have more of a 'ring' than the mica one, but its also thicker which might compress the gaskets too much :!:

https://youtu.be/BSfWrBLuN_M

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Inigo
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Re: Little Thorens Gramophone

Post by Inigo »

Your experiments are very interesting. I've also made some copies of the Meltrope diaphragm with thin aluminium sheets from food trays, and they sounded as good as the original. I keep a box full of bits of things I collect that seem suitable for diaphragms, as thin stiff plastic sheets, thin porex sheets, metals, etc. for experimenting. I've read that the better phonograph diaphragms made by a fellow colleague are the truetone ones, which I read somewhere were made from pressed porex material. I want to try it myself.
I keep in that box any bit of modern materials that I feel sounds 'gramophonic' when scratched with a fingertip.
Inigo

jboger
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Re: Little Thorens Gramophone

Post by jboger »

mrrgstuff:

I have watched your videos with interest and like what you are doing. I do have a couple of comments (don't we all?). For this type of reproducer, one in which the diaphragm is inserted through the front, I have found the original mica to be a bit oversized compared to the opening. The thinness and flexibility of the mica provides some "give" so one insert the mica. You of course can not do that with the cd case. Now I would like to make a prediction. I believe your new diaphragm is too thick and rigid to set up a good sound wave with sufficient amplitude; it may vibrate with the needle but not really flex. But we are all good experimentalists and the proof's in the pudding. So I wait to be shown wrong.

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