I tried that already. I constructed a plinth for my Technics SP-10 MK1 and Garrard 401 a year and a half ago. It is not fun or easy to change a armboard with tonearm in it. It is more difficult to change the whole TT. It is very easy to damage the TT or anything under it and as you said, it is a very very stupid idea:) !
T-Bone, you almost lost me there with all the switching around, but if you do a plinth right, I believe it would be really hard to pull off. The reason is because different mechanisms require different sorts of tuning. Different top plates resonate in different ways, too. A plinth that might bring the best from an SP-10 might not do so well for a Garrard 301. It seems like a tricky proposition to me.
I re-read my post afterwards and it is confusing. I am thinking of building a CLD "donut-plinth" and then seating that "donut-plinth" within a larger plinth which would have the tonearms. The other way to look at this would be to think about it as a "table-board" the same way one has "arm-boards" for that kind of plinth.
I hadn't really thought about how much different a plinth would have to be between a couple of different TTs. It is not surprising, however, that they might have to be different to be perfectly matched to the table and top plate. I would almost expect that using a different kind of "table-board" inside a large/heavy plinth frame would actually go a fair ways to accomplishing that, but the answers so far point away from this.
Mosin, assuming different mechanisms require different sorts of tuning, how does one acquire the knowledge to know without a huge amount of experimentation what the best starting point is for a particular mechanism?
Hi, everyone is discussing about plinths. The bigger the better. Why such neurosis? Plinths are pretty to look at but do they really give much sonic improvement? Plinths could add colorations to the sound --> is that what you want?
T-Bone said, "Mosin, assuming different mechanisms require different sorts of tuning, how does one acquire the knowledge to know without a huge amount of experimentation what the best starting point is for a particular mechanism?"
This is a good question, and I do not have a ready answer for it, except to say that each material used should be with purpose, and not simply a guess. It is experimentation really. That, and research of the materials present and those you plan to add. If you look at a turntable as an entity unto itself, that is the only way to reach any sort of meaningful conclusion. Otherwise, you won't have a clue about what you did right, or what you may have done wrong. In the end, it may look as if it was easy, but that won't necessarily be true.
T-bone, I cannot speak from the experience of trying your idea but I foresee many downfalls -
* Consider the variations in cutouts required for SP-10, 301, 124, etc. Your idea would require the largest cutout of these for your donut, something that might not allow as much support or mass as a custom cut out for one of the smaller footprints.
* Different mechanisms generate different resonances and vibrations, thus requiring different materials. For example, the famous Lenco site began recommending layered MDF, although later a sandwich of ply and MDF has been favored. At least one SP-10 site recommends against MDF. So, what materials do you use?
* Considering the potential mass of your plinth and some of the motor units (plus the top board), switching back and forth like armboards is hardly comparable.
* From all my reading on plinth design and building, one point is consistent - the need to securely couple the motor unit, plinth, and arm. Some folks use both screws and glue in constructing plinths. Designing for a removable top board might require 20 or more screws to truly secure it to the base (donut) plinth. How interchangeable would that be?
So to close with your own words, my thought is this would be a stupid idea.
I think it easy to design a plinth or multiple plinths that allows for interchanging tonearms, that is, to make all the plinths to be able to accept the same armboard or mounting mechanism. And that is a better idea to experiment or to play with different sound than to have a fixed plinth. A plinth might work well for one table but not for a different one. But keeping the tonearm and cartridge the constant can tell you a lot about turntable genres. People like to mess with plinths and platters, I prefer to swap out motors - in a belt-drive (or to a lesser extend, idler drive) turntable of course.
I thought about that, but frankly, figured that was more of a hassle, and more expense than what I am thinking of. That said, I am still wondering what the right way to do this is. The idea is still more for fun than anything else. It is of dubious utility unless one has multiple tables to plinth and one only wants to use one motor at a time. It is a tinkerer's toy, not a music machine.
Your idea would not allow each table to sound it's best due to compromises in design necessary for it to work, but even if it were practical, it would be more work for only two decks than simply building two plinths. i.e., if you had ten TT's to plinth, maybe (though I wouldn't), but for two, why bother?
Not to be unkind, but this seems like one of those ideas that might deserve a moment or two of internal dialogue, and then immediately dropped.
Everything we have done at OMA with slate plinths has been aimed at mitigating or eliminating the top plate in plinth designs, so its ironic that you would like to revisit the top plate, though I understand the seeming advantages in convenience and economy.
Unfortunately, if you care about the sound, its not a very good idea.