Mounting Triplanar Tonearm to SME 20/2 Turntable

I have a 30/12 and rock solid is an understatement. Aluminum may be lighter than other metals but it is still pretty heavy. It is used in this application because aluminum does not ring. It is self damping and in the thicknesses used by SME real stiff. I own one so you could say I am biased and there may be cooler looking tables out there but IMHO none that sound better. Maybe as good but not better.

Today my machinist friend confirmed that the SME arm board material is brass.  He's going to make the blank version for me out of brass as well.  I'm surprised to hear the plinth is aluminum.  It's such a heavy turntable, and besides that I would think aluminum would not isolate vibration as well as some combination of materials.  If it is aluminum they did a great job making the thing rock solid.  Thanks

snack, the SME plinth is aluminum.
Atmasphere, I absolutely agree that the tonearm has to be rigidly connected to the main bearing but I'm not sure the arm board has to be exactly the same material. It certainly has to be rigid. Plain wood of any species is not a good choice because it is not dimensionally stable. However MDF Laminated with aluminum or a heavy plastic or solid surface material should be fine. You can even make the MDF harder by soaking it in Watco overnight. 

I made a temporary arm board last night from aluminum disk material I found online, and mounted the new tonearm.  It's not real pretty but it works great.  It only cost me about $30 for the materials.  At least I can listen to records while a nicer version is being machined locally.  

The Tri-Planar arm is an amazing work of engineering.  I'm already blown away by it.  I've only played one record and still need to tweak some things, but it's immediately evident that it's a wonderful tracking tonearm.  

A friend of mine owns a machine shop and has agreed to make one for me.  BTW, I think the material for the SME original is brass.  I took it off the plinth and noticed it feels much heavier than what aluminum would weigh.  
I'm going to see if I can get the new one made from brass as well.  
Also, a guy in the U.K. offered to make a custom board for 670 UK Pounds.  I think that's more than $800!  Crazy.

Happy Triplaner owner here also, I would suggest the visit with Tri to get you up and running and also establish a relationship- wish I was that close to him! He has always treated me well and I bought my arm used here on the Gon. 
On the subject of a third hole, not many two legged stools on the planet, but you can certainly try... 

as far as experimenting with other materials, Why not ? You may pick up some more critical listening / evaluation skills to boot. 
Enjoy your arm, I love mine ( on a Brinkmann Bardo w Lyra - she sings happy

As others have suggested make a new armboard  a local machine shop should be able to help you.  Tri’s setup jig is a little “rough” when I mount Triplanar arms I use my DR Feikert jig on the tonearm directly then mark the hole locations on the blank armboard.

Are you selling the 4.5 ? If the price is right I’m interested 

Best of luck

Peter 

I mounted a Triplanar on a SME 10, you @snackeyp might of bought the arm from me? Any how I had an armboard made of Delrin by Brian at Analogue Artisan and worked great he is in New Hampshire and does very good work. If you look at my profile I put some photos of it there. I found it difficult to work with Triplanar as far as getting an arm board   http://www.analogueartisan.com/

Right???

@millercarbon  I do talk with the voice of authority fairly often, which probably isn't the best way to present things. But I try to temper that with simply not responding if I have any doubts. FWIW dept.: I own two Triplanars and Triplanar is a 10 minute drive from here. We also make a turntable - the model 208. I've serviced turntables of all types as I put myself through engineering school repairing consumer electronics. So I was expressing the mechanical engineering issues that are common to all turntables.


This issue is not unlike the steering in a car. The car has to keep the wheels on the road at all times, and at the same time you have to be able to steer it. To do this, there can't be any play or flex in any of the steering or suspension components or else the handling can get creepy really fast. In a turntable, there can't be any play between the surface of the platter and the locus in which the cartridge is held. If there is, the stylus will be able to move in a way other than the grooves of the LP dictate (introducing chatter and/or coloration). To this end there can't be slop in the bearings nor flex in the plinth. The arm has to be rigidly coupled to the platter bearing - as rigidly and also as 'dead' as possible (the latter being why damping a plinth affects the sound).  Otherwise that would be much like a flexible part in the steering of the car- and would result in the wheels not doing what you want.

Three choices. #1 buy a new tonearm board.
#2 laminate 1/2" MDF to the current tonearm board to cover the hole. Spray paint it black and make sure you can lower the new arm enough to get it down to platter level. 
#3 Make a new tonearm board. Layer plastic and aluminum layers to get the right thickness using slow set epoxy. Use the old board as a temple to router the board to exactly the same shape. 
If you don't have the stuff to make your own just buy a new one. 

@atmasphere Thanks for your advice, Ralph.  I appreciate it because I know you own a Tri-Planar and it was your recommendation on these forums that I began researching them.
For the record, the plinth of the SME deck is not the same material as the arm board.  The arm board looks like machined aluminum.  The plinth is something else, I'm not sure the material.  
I'm considering making the existing arm board work, but haven't decided yet how.  Tri Mai says he can help me figure this out if I want to go this route.
I've also contacted SME about ordering a blank arm board from them.  I'm assuming the price for this will be more than I want to pay.  They charge $9 for one of their own hex wrenches (standard metric sizes), as an example of how over priced their accessories are.  One can only assume the arm board will be hundreds of dollars.  That said, if going this route is the best way I will spend the money.  
@imhififan Thanks for the link to the etsy listing.  That would likely work just fine and be very affordable.  
@millercarbon Thanks for the suggestions.  Much appreciated.  I like the idea to experiment with different materials.  

My suggestion is make a new aluminum arm board for your arm.

https://www.etsy.com/listing/194959127/aluminum-round-disc-circle-6061-250-14?gpla=1&gao=1&&...

https://www.gcaudio.com/images/uploads/777/sme-20-diagram_square.jpg

This will result in reduced performance

.
"Will"? WILL??? 

Or, "I think it will". Or how about, "According to something I read somewhere it will." Or better yet, "I'm guessing with no real clue that it will."

Apprently someone didn't read the post above. Either that or doubts what was heard and written. Because if it really is so important for the arm to be coupled then why does it sound so much better when its not? And if its really so important for materials to match then why does it sound so much better when they don't?

Another thing I notice, conspicuous by its absence, is any mention of having actually made comparisons and learned from experience. Not one word along the lines of this is based on experience.  Instead all we have is unsupported unsubstantiated opinion.

Right? Right???

I could also have a wooden disk cut to the same size circle as the SME arm board and attach the TP arm to it. I don't want to detract from the aesthetics of the system, but I suppose I can paint it black so it blends OK.  

This will result in reduced performance. Here's why:
One thing that is really important in any turntable is the fact that vibration occurs in the plinth. If the vibration is different in the arm mount as opposed to the platter surface, it will be interpreted by the pickup as a coloration. So the armboard should be of the same material and as tightly coupled to the plinth as possible. Anything else will introduce a coloration.


If I were you I would get a blank arm board from SME and simply drill the three mounting holes for the screws.

Looking at your table and arm, you could take a hole saw and cut some arm mounting blanks out of different materials- wood, acrylic, aluminum, whatever. Cut a slot and you will be able to swap them out without even having to disconnect the phono leads. Make them all the same thickness so you don't have to mess with VTA. If your local guy can help, ask him if he has some scrap wood or whatever you can try this with. Then when you find what you like best have him make you one sanded all pretty and nice.

Take your time. Big mistake everyone makes is thinking they can figure it out or take advice and do that and be done. Which you certainly can do. But you will be missing out. Because this is not rocket science, nor is it even science at all. Or even exact. My arm sits in a hole and seems quite stable and fixed, yet its really just sitting in a hole held in place by its own weight. Probably some wannabee is right now typing away at a post getting ready to flame on me for the impossibility of this sounding any good at all due to the imprecision of the hole slop, inability to ground vibrations, lack of constrained layer damping, or whatever. As if I haven't heard with my own ears how much better it sounds.

Right now is the best time, you can easily experiment with different things as simple as cutting pieces of wood, acrylic, etc and trying them out. Anything from tape to clamp to a screw or two, anything to hold the arm in place long enough to play a little music. You can for that matter even hear the difference between one screw and two, tight or loose, tape or screw, etc. Guarantee it will not take long to hear what's going on, in fact you will be surprised how fast and obvious it is, and it don't have to look pretty or anything. Try it out, be amazed what you learn. One day, few hours, be ahead of 99.9% which is being generous, as I doubt if even 0.1% have done the kinds of things I'm talking about. 

@

This doesn't mean that it's an acceptable application. Just curious.  

Regarding the 3M UHB tape as your aware they make both
quite thin and thicker versions. I also use it often and 
am offen surprised at its applications.  

Dear @snackeyp : First than all contact directly to SME asking for advise(help I think they will help you:

enquiries@sme.co.uk   or  +44(0) 1903 814321

In the other side you can do it only with those two holes or with the 3M tape but you don’t lost nothing to contact to the manufacturer of your TT.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

@millercarbon I can drill two holes and might just do that.  The third hole is not possible since it's in open space.  
I could also have a wooden disk cut to the same size circle as the SME arm board and attach the TP arm to it.  I don't want to detract from the aesthetics of the system, but I suppose I can paint it  black so it blends OK.  
One other thing is I live in St. Paul, which is where Tri-Planar HQ is located.  I've contacted Tri-Mai and he said he can help me set it up.  I would still like to hear other ideas on how to best convert this before I meet with him.  Thanks for your help!

Why not just drill the hole where you need it??

But yes, tape will be just fine. Possibly maybe even better. In fact the main drawbacks to tape are its a little harder to tweak into position, and then also to remove, depending on how permanent the bond.

My Origin Live Conqueror mounts sitting on an aftermarket jig that makes VTA adjustment easier and more precise. This includes a layer of teflon between the arm and base. It allows the arm to float. Tried it both ways, its better like this. In other words this like everything else you can never assume but just have to try it and see. Only way to know for sure.

In this case you could for example try fastening the arm with the two screws, then try with tape, then if two screws are better go back and add the third. Or not. There is no right or wrong- as long as the arm doesn't go flying off and crashing to the floor!