Re: How to get more Bass from a Orthophonic Reproducer
Posted: Sat Nov 12, 2011 7:22 pm
If the diaphragm is air tight, then I'd second the notion that the ball bearings might be binding. I had this issue come up with the brass Orthophonic sound box I had some 20 years ago. It never did sound as good as a standard pot metal version. I actually swapped it for a couple of sound boxes, and the person who got it from me noted that it looked like the ball bearings had been installed with a steel punch press. Replacing the bearings, he said, vastly improved the bass response.
In any event, to test the bearings, you might want to put a drop of very lightweight oil onto them, or even a tiny bit of Lock-Ease (graphite powder) and then insert a needle and flex the needle very gently--not to much! The diaphragm should plunge evenly, with very little effort.
As for the gaskets, I believe they were rubber backed paper. They were designed to hold the edge of the diaphragm rigidly in place, so that the corrugated ring would be responsible for the main pivoting action.
One do-at-your-own-risk tip I have is to put a drop or two of some Goo-Gone onto the edge of the diaphragm and swish it around. (Don't apply it to the spider seals.)
I did this to the pot metal sound box attached to my 4-40 about three or four years ago, and it noticeably improved the sound quality. For whatever reason, the diaphragm became more flexible, and there was far less surface noise from any given record. For good measure, I also put a drop of Goo-Gone on the ball bearings, as well. I was actually planning to have the sound box professionally overhauled, but it has worked so well--far better than any other one I've owned--that I've left it as-is, save for re-packing the throat's shrunken, dried out O-ring in silicone caulk and reinserting it, as recommended above. (I also applied a coat of Krazy Glue to a few hairline cracks on the outer shell, and then shellacked over them. So far, they've never opened or spread.)
HTH,
DS
In any event, to test the bearings, you might want to put a drop of very lightweight oil onto them, or even a tiny bit of Lock-Ease (graphite powder) and then insert a needle and flex the needle very gently--not to much! The diaphragm should plunge evenly, with very little effort.
As for the gaskets, I believe they were rubber backed paper. They were designed to hold the edge of the diaphragm rigidly in place, so that the corrugated ring would be responsible for the main pivoting action.
One do-at-your-own-risk tip I have is to put a drop or two of some Goo-Gone onto the edge of the diaphragm and swish it around. (Don't apply it to the spider seals.)
I did this to the pot metal sound box attached to my 4-40 about three or four years ago, and it noticeably improved the sound quality. For whatever reason, the diaphragm became more flexible, and there was far less surface noise from any given record. For good measure, I also put a drop of Goo-Gone on the ball bearings, as well. I was actually planning to have the sound box professionally overhauled, but it has worked so well--far better than any other one I've owned--that I've left it as-is, save for re-packing the throat's shrunken, dried out O-ring in silicone caulk and reinserting it, as recommended above. (I also applied a coat of Krazy Glue to a few hairline cracks on the outer shell, and then shellacked over them. So far, they've never opened or spread.)
HTH,
DS
