old country chemist wrote:
Hello Paolo, What a pity that your diaphragm is damaged-probably due to someone poking their finger in through the hole at the back perhaps. I should think that if the diaphragm was removed, it could, with care, be restored to it's proper shape. You would find it difficult to get a spare diaphragm for your soundbox as it is such an unusual design, BUT another aluminium diaphragm of the same diameter could be used in it's place. A pity you are not closer. If you were, I am sure some of us would be delighted to repair the diaphragm for you. If you gave me the diameter in millimetres, I would have a look to see if I could find one to fit. I noticed that there was no sealing wax on the stylus bar screw that is attached to the diaphragm.
Alastair.
Hello Alastair,
sorry for being so slow in answering. Your kind words and help are much appreciated, but may be I partly addressed the issue. Yesterday evening I locked myself in my attic cave and in a surge of incredible courage I disassembled the soundbox! Despite what I though at first, the only raised part of the diaphragm is the central area around the needle bar hole: all the rest is supposed to lay flat (or so it should). So I took a small hammer and gently tap around the outer ring insisting on the warped area: somehow I managed to get it flat again. I then proceeded to put in place the diaphragm on the bottom gasket and carefully inserted again the upper one (which had snapped in one point during the previous removal operation).
By the way you were right concerning the needle bar screw: I did not see any wax when unscrewing it, but there was a small remnant of a sticky substance, which I think was put there to prevent the screw from getting loose.
Now the soundbox is assembled again and, while far from perfect, sounds way better than before without that annoying buzz that had alarmed me. The gaskets are not rock hard, but of course have become brittle and lost elasticity, so I expect that a careful replacement of them will lead to further improvement in sound quality. All in all I'm satisfied: may be it's not a top quality soundbox, but at least it's an all original item . By the way: after the "repair" I measured the outer diameter of the diaphragm and found it to be approximately 50 mm.
Thanks again to all for your interest and have a wonderful start into the incoming new year!
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File comment: Diaphragm O.D.
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