Silly turntable question

(The question, not the TT!)

I'm assembling a turntable setup, slowly over time.
At this point I have an SP-10 with the factory
obsidian plinth/cover. I have a new SME-V for it
that I bought about 6 years ago (I did say slowly). It's
not even set up yet, let alone having been listened to.

Now, I've gotten the idea in my head that I want a 12-inch
arm instead, the SME-312. THAT would mean selling the
obsidian plinth and buying something custom, as well as
buying the new arm.

I'm willing to admit that I must surely have some mental
quirk to want this change, untested.

Even so, I humbly ask you, what could I expect soundwise
if I followed through with this proposed upgrade ?
Subtle improvements ? How subtle ?
Or, should I just be happy with what I have ?

Speakers are DIY custom built, amps are Brystons,
listening room is way too small.

"Do you think I'll be happy ?" What a question.
I can guarantee that you will never be happy about a system you never set up.

We can make your dream turntable which will make you happy :-)

However sometimes just completing something makes you feel real happy - I know once this one delivered and set up - ill be very happy.

As Always Good Listening

Getting the TT up and running is just the starting point for a many year tuning and tweaking process. You will have many ups and downs doing this - get started. The length of the tonearm is not the most important aspect of good vinyl sound.

Some cartridges work better on long arm, some work better on short arm. It depends on what you have.
Getting the TT up and running is just the starting point for a many year tuning and tweaking process. You will have many ups and downs doing this - get started. The length of the tonearm is not the most important aspect of good vinyl sound.

You might ask Albert Porter here for some thoughts, he has marketed a custom plinth for the SP-10 (I'm not shilling for him, just making it clear that he does business in this space) and has fooled around with a number of different arms, including the longer SME.
I have an old SP-10 that is sitting idle, bought it new back in 1974. Unfortunately, it is a mk i, not the better mk ii or iii, so I'm not inclined to sink alot of money into it right now. At some point I may bring it back into play for a vintage system. I will tell you, based on my experience with the older plinths for the SP-10 that the concepts of isolation were not as well advanced or executed as they are today. Mine, which was mounted in a gorgeous Music & Sound wooden plinth, was microphonic as hell. There's also been a fair amount of discussion here about running these naked, with a free standing arm pod, but I gather that's fairly controversial insofar as the SP-10 is concerned- not sure why it wouldn't work if the turntable mounted to something that did a good job on isolation. My current table (a Kuzma) works that way- the arm stands 'free' of the table on its own pod and gives you the flexibility to add several arms. However, that table depends on mass. And it is a motha to isolate properly and get level.
Good luck.
I suspect that a change to a 12" arm will be subtle, and not necessarily for the better. Depends on the cartridge you use.
I agree with those who suggest that you simply get started. However, to answer one of your questions: there is quite a difference between the 9" and 12" SME arms. I spent two weeks directly comparing the SME V to the SME V-12 on an SME 30/12 table using the same cartridge and cable.

Moving up to the 12" arm was like going from a highly resolving two-way compact speaker to a three-driver, three-way floor standing speaker. Extension and weight improved as expected. But unlike with some such speaker changes, there was absolutely no less coherence or sense of balance. There was just more information presented in a cleaner and clearer way and there seemed to be less distortion. IMO, well worth the cost to upgrade.

But changing the plinth and selling your unused SME V just to accommodate a new 12" arm may be more hassle and expense than it's worth right now. Check your priorities, get started, and join the fun.
IMHO, the Panasonic obsidian base does not sound that great. My recommendation, first if you have a regular SP-10, sell both it and the base and get an SP-10 MK2. There is no comparison here. Make, or buy a nice Baltic birch ply plinth, or if it's in the budget, go slate. All of the above is going to be better bang for the buck than a 12" arm. But if you have the dosh left, go 12". As my mistress says, size does matter.
Dreaming about it is always better than doing.

So I say yeah, sell the arm and buy the longer one. THEN sell the plinth and spend a few years finding someone new to make you a custom one.
If you stall long enough, maybe your table will never get finished.
But if it DOES seem like it may near completion, you can always waffle, and buy a second short arm again, then again sell the plinth, and get another new one made to handle BOTH arms..
All this should take at least another seven years..
And once you have a table, two arms and a plinth all assembled, you can spend forever deciding what cartridges you want in your arms.. and what phono preamps to use..
This could take a lifetime if you work hard at waffling.
But Elizabeth, isn't this part of what we do as hobbyists- consider changes and enjoy the process, from conception to implementation? I didn't read the OP as someone who deserved thrashing for failure to implement after years of kicking around the idea....
But Whart, Elizabeth merely stated the truth. The OP has in fact been contemplating without implementing for years.

I have a new SME-V for it that I bought about 6 years ago...
It's not even set up yet, let alone having been listened to...
Now, I've gotten the idea in my head that I want a 12-inch arm instead...
J. R. R. Tolkien wrote a little essay, 'Leaf by Niggle', in which he jauntily thrashed himself for endlessly rewriting favorite tales without ever finishing one. It was his publisher who forced him to complete 'The Lord of the Rings' (more or less). Absent that pressure he never would have. He'd have niggled happily for even more decades amidst his unfinished tales, leaving only fragments that his son eventually assembled into a functioning narrative.

The OP has been niggling happily for at least six years and is niggling still. Perhaps, after more decades have passed, he'll leave behind fragments that his heirs will eventually assemble into a functioning vinyl rig. ;-)
Peter, the OP is thinking of moving from 9" SME V to 12" SME 312. That's quite different from the move you made and less likely to be a clear step upward. Regardless of length, the 3xx series is not in the same league as the IV/V series.
Seems silly to me to have something and not even try it before you get something else. It will at least give you more perspective on the differences between the two. I suppose if your SME V in still in the box and has never been used it may be worth more when you sell it.
My apologies to Elizabeth. My reading skills are obviously going south.
Mea culpa.(Although I admit to having projects, like getting my old Quads
restored, that have just languished). And Doug, thank you for the kind
Dear Noslepemus: IMHO you can't help you with this kind of thread when you did not even set up yet the SP10!!!!. Why to worry about the tonearm right now?

I agree with Aigenga: " make the TT/tonearm/cartridge set up " and listening to it. Then fine tune what is that set up and listen.

After that you could think on some chages down there: from TT plinth, cartridge, tonearm, phono stage and the like.

Btw, IMHO the best plinth in any SP10 is NO PLINTH at all. You could make an Agon research about and when you will be ready to take a plinth decision then you can take that " road " or whatever you want, just an opinion.

Regards and enjoy the music,
You are absolutely correct, your question is silly. Anything you actually implement would be an improvement over the silence emanating from your current rig.

improving the phono stage, cartridge, or your skill setting things up, would probably make more of a difference than going to a longer tonearm.
First, thank you folks very much for your comments !
I'm the first to laugh at myself about this, I have other
unfinished projects at home on par with this. I seem to be
pretty good at starting projects but not as good at

I have an old Clearaudio Accurate cart (12g, 15cu) that
"should" resonate at 8.06Hz on the 14g SME-312s, and at
8.57Hz on the 11g SME-V. So that would indicate I probably
need a new cart too if I bought the 312s. I could of course
just try it on the -V and not spend any money. Don't know
if this considered a match made in heaven or not.

If I did not use the -V, I could probably get a bit more
on a sale/trade-in, this is true.

Some of you have given me powerful arguements for further
It is a Mk-II I think, it has the separate power supply
and speed control display.
Noslepums, My post above was written under the assumption that the 12" SME arm you are contemplating is the SME 312S, though you wrote "312". The 312S is a new generation magnesium arm based on the SME IV. It differs from the V-12 by having a removable headshell (convenient for cartridge swapping and azimuth adj.) and by also having dynamic VTF adjustment. For me, the latter is more important than the former, but for others, maybe not. I'm not familiar with the 312.

Albert Porter has the 312S arm and is getting a V-12 for comparison. I've never heard the 312S. I agree with everyone else that the length of your arm should be of a lower priority to others for getting started. Set up what you have and enjoy some records. Then go from there.

If you follow Raul's advice for a nude SP10 with an arm on an arm pod, then switching to a 12" arm later should not be an issue besides adjusting for the new alignment. Have some fun.
Some of you have given me powerful arguements for further thinking...........;)
ROFLMAO!!! I'd hire you to fix my car... if I had a spare car.
If you are at the point of having something (anything) to enjoy vinyl..
plug in and go from there. Dream as you go, the old saying "a bird in hand is worth two in the bush" comes to mind.
The best thing about vinyl is the listening.. on anything.
Years ago I bought a new Rega P25 from a guy who'd bought it only a few weeks before & never even taken it out of the box. He said he was selling it to buy a way more expensive TT.

I never understood that--selling something that nice that he'd never listened to. BTW I loved the P25 & the Benz Glider he included in the sale.....of course I also spent much time finding the right phono stage, buying a record-cleaning machine, etc.