Inigo wrote:How nice!
I believe your sounds boxes actually give less volume than the hmv no4 because they are too light, while the diaphragm stiffness and the rest of things are similar.
I'd suggest you to try your soundboxes with two improvements. One, to add mass to them; a pin at the top where you could insert washers, nuts, etc could serve the purpose. Two, to install a flexible rubber coupler between the sb and the tonearm, to avoid the sb body vibrations from reflecting back to the needle. Maybe you should test soft rubber connectors, and slightly harder ones, to find which stiffness produces the best sound.
With these tests you could be surprised, maybe the fund gets rounder and fuller...
Thanks Inigo
. I've now fitted this to my DIY soundbox and made a video comparing it against the mica diaphragm - and also just the plain sheet aluminium I had previously used.
https://youtu.be/mK1bGhanqf4
Yes the weight of this soundbox is only a little over half of that of the No.4 - but in a very basic test which I did with the mica diaphragm fitted - the volume was comparable to the No.4 (its about 6m 35s through the video below)
https://youtu.be/GwkSmJzJ_bU
Its also not easy to see - but there is an O ring isolator between the back of the soundbox and the main body of the soundbox. In future designs I may make this a much bigger and thicker isolator - as I doubt it is very effective currently
Thanks