Re: Homemade diaphragms
Posted: Wed Dec 21, 2022 1:34 pm
Brilliant work! The diaphragm looks perfect, as do the annular rings. And the EMG/Meltrope style back looks great. I am always in awe of those who understand and use new technology.
https://forum.talkingmachine.info/
Looks great!! I hope you can sell the two pieces of those stamps to make the diaphragms on ebay. I will buy them. Thanks.anchorman wrote: Mon Dec 12, 2022 12:28 am I have been working on a meltrope style back and aluminum diaphragms for a Victor exhibition soundbox given to me by a fellow collector a little while back.
The back was 3D printed, and I 3D printed some molds to make the rubber bushing in various sizes. I also 3D printed a form on which to emboss the diaphragm from aluminum. The aluminum used was from the top of a large tray that food came in at work. No annealing necessary, as it was already very soft and easy to form. A simple wooden tool was enough to make the ring shaped ridges, and stiffened the center of the diaphragm marvelously, while allowing it to flex around the edge.
It does not have as flat a response as the Columbia number 9, or the HMV 5b, and is not so loud. I think some of this is due to inferior springs used in the exhibition, and these will hopefully be replaced with point contact springs similar to EMG/expert soundboxes.
Attached here are some videos comparing the sound of this soundbox playing on an HMV 102, along with the 5b, and a Columbia No 9.
https://www.youtube.com/watch?v=KcSO93o-jdI
https://www.youtube.com/watch?v=06tB3-0b-_Y
https://www.youtube.com/watch?v=2md-DzMQ8Gg
It’s hard to get a real feel for the tonal changes with these recordings, as the levels are automatically adjusted when recording on my phone. Hopefully I’ll get a better recording setup at some point with manual control of the sound level. Regardless, there is some difference to be heard between them.