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Posts: 1368
Location: Tokyo
Joined: April 2, 2003
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you'll find the SH-10B3 manual to be correct... The surface is "obsidian." I had always thought it was 'obsidian glass' made of a 'man-made' silicon dioxide mixture rather than obsidian carved from a solid hunk of volcanic residual (which would be prohibitively difficult to do I would have thought because of the way glass can shatter when you cut or grind a bezel or holes into it)]. I do not know if naturally-formed obsidian chunks can be re-melted and used. If so, that would have been one way to do it. Note that most man-made glass melts at roughly the same temperature as stainless steel when you use soda ash in the processing so it probably could have been done in-house. If you take apart the plinth, as I did once several years ago, you will see that the 'mahogany' veneered CLD-style material and the 'obsidian' have a rubber gasket between them, and when you remove it to look at the 'obsidian' plinth by itself, the inner part is quite gray, and it appears to be 'molded' and a different material. It has a different 'touch' and it conducts heat differently (the obsidian is cool to the touch, the inner part is not). There is a clean straight edge (that you can probably see in some places - perhaps near the hinge - even if you do not take the wooden part off) which is about 3mm thick. That is the 'obsidian' outer shell as far as I can tell. The inner part, and the bulk of the weight of the upper half of the plinth, and the place where the mounting screw holes are sunk, appeared at the time to be the molded resin compound. I probably should have said "TNRC (Technics Non-Resonant Compound) which for all its weight, and considerable resonance-draining/damping properties is PROBABLY some kind of petrochemical-derived polymer/resin compound." I did not know what that compound was made of, but it looked to me like it was some kind of polymer, perhaps with very finely ground stone powder in it to give it weight. It is quite dense in the form it takes in the plinth innards, and in Sony's plinth. When I asked around, I was told that it was a plastic-polymer of some sort, but that was from an industry person who knew the Sony stuff, not someone who knew the Technics stuff (but they are supposed to be quite similar compounds). That said, the Sony stuff looks from the outside like it is obsidian too. It is eminently possible that it uses reconstituted silicon dioxide (plus something) to give it color and hardness to the outer layer, and the inner layer has a different composition. I don't appear to have a copy of the SH-10B3 or SH-10B5 manual at hand, but turning over my SH-10B5 just now, I also note that the surface underneath is different than the surface above, both in finish, and in heat conductivity. The underside of the SH-10B5 is very cleanly molded and on one of mine, there are scratches which are somewhat deep near a corner (which would not happen if it were real obsidian, or man-made obsidian. Real obsidian would chip cleanly. I know because I have had a few chipped SH-10B3s before). When I took mine apart, I dug around (online) in Japanese to find out what it was. I remember seeing a Japanese reference to the fact that the SH-10B5 was one molded piece of T.N.R.C. (which is used as a non-resonant piece for a number of parts in the Technics line, including the shell-plinth of the 5300 series, and perhaps later tables in a thin layer, and, IIRC, some parts of the underside of the casing of the SH-10Mk3 housing). EDIT:
edited once to add the link to Nisi-san's website.
edited a second time to fix some phrasing which had missing words. At the bottom, it mentions that the SH-10B5 is made of a single block of T.N.R.C. The quote:
"ＳＨ１０Ｂ５は，テクニクス自慢の音響素材Ｔ.Ｎ.Ｒ.Ｃ.（Ｔｅｃｈｎｉｃｓ Ｎｏｎ Ｒｅｓｏｎａｎｃｅ Ｃｏｍｐｏｕｎｄ）による一体成形で，重量は，巨大トルクと重量級ターンテーブルのＳＰ-１０ＭＫ３に対応するため"
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