Need help restoring a Meltrope III soundbox
Posted: Tue Jul 03, 2018 11:21 am
I've recently acquired a Meltrope III from a friend in the UK. One day I decided to overhaul it, as I compared it with my restored HMV 5a/5b soundboxes and found the sound of the Meltrope rather dull in comparison. This was never touched before (original) and when disassembling it I noticed a hardened front gasket. So I decided to renew the gaskets. I took everything apart and put new soft rubber gaskets behind the diaphragm and in front of it. I noticed a better sound, but still boxy, not the open sound I expected. Usually the Meltrope III is compared with the EMGs, etc. as a very good soundbox.
The first odd thing I noticed was in the front gasket, the one just behind the cover. I noticed when reassembling that this gasket is pressed against the needlebar oval plate, the one which acts as a fulcrum. So it prevents the needlebar free movement. Also, the gasket is pressed into place by the soundbox cover in a somewhat strange fashion.
Thinking later about it, and disassembling it again, I discovered a third rubber gasket hidden in a deep groove at the back; a deep groove between the soundbox body and the center portion at the back, which is raised. That gasket was also very hard.
The question is: the original arrangement was this one? a double back gasket? (1: the one into the deep groove, and 2: another one on top of it)? Then the diaphragm, then the front gasket (3), pressed against the cover and also under the needlebar fulcrum plate? It is a bit strange.
I decided to put only the gasket in the groove (1) then the diaphragm, then the front gasket (3). This arrangement avoided touching the fulcrum, and also the cover was less jammed and forced onto the front gasket. It seemed reasonable, although the diaphragm is almost touching the raised center portion of the backplate, resulting in a very thin air chamber behind it... It looks better, but I suspect this is not right either... The sound continues being very boxy, and not as true and clear as with the 5a/5b.
Can any kind soul explain to me how to assemble this soundbox properly? How many rubber gaskets it should have?
Thanks,
Inigo, from Spain.
The first odd thing I noticed was in the front gasket, the one just behind the cover. I noticed when reassembling that this gasket is pressed against the needlebar oval plate, the one which acts as a fulcrum. So it prevents the needlebar free movement. Also, the gasket is pressed into place by the soundbox cover in a somewhat strange fashion.
Thinking later about it, and disassembling it again, I discovered a third rubber gasket hidden in a deep groove at the back; a deep groove between the soundbox body and the center portion at the back, which is raised. That gasket was also very hard.
The question is: the original arrangement was this one? a double back gasket? (1: the one into the deep groove, and 2: another one on top of it)? Then the diaphragm, then the front gasket (3), pressed against the cover and also under the needlebar fulcrum plate? It is a bit strange.
I decided to put only the gasket in the groove (1) then the diaphragm, then the front gasket (3). This arrangement avoided touching the fulcrum, and also the cover was less jammed and forced onto the front gasket. It seemed reasonable, although the diaphragm is almost touching the raised center portion of the backplate, resulting in a very thin air chamber behind it... It looks better, but I suspect this is not right either... The sound continues being very boxy, and not as true and clear as with the 5a/5b.
Can any kind soul explain to me how to assemble this soundbox properly? How many rubber gaskets it should have?
Thanks,
Inigo, from Spain.