Technics SL12xx & 12" Arms.

[The Vinyl Adventure]

what dave said

[Mike_New]

I will proceed with making the first prototype and post a pic ASAP

[Gdg]

Mike, that's could be very interesting. The 12'' tonearm is reallly the further step in SL 1200 upgrade.

[Gdg]

Some 6 months ago I designed a 12" adapter plate which bolts into the existing arm well of the SL1200xx and cantilevers over the back edge to occomodate a 12" arm.
This way you do not need any additional carrier.
Would this be of interest to people?? The dust cover cannot of course be used and would have to be removed. Also more shelf depth is required.

I did not proceed with this at the time as there did not appear to be a great interest in 12 inches! However with the increasing use of the new bearing and copper mats, together with the future takeup of the new platter, all of which justify the use of a longer arm. I have noticed that the interest in 12" arms has increased.

Mike, any news about this ?
Bye

[jrhymeammo]

Hello to dear members at the Arts of Sound.

I have just signed up to this site after seeing this.
Has anyone here actually tried out the unit?

Have Fun,
JRA

[Mike_New]

Gdg,
I have sketched out a couple of design options on my CAD system, One of which fits into the existing arm well and clamped into the three holes. This does not involve any additional drilling of holes and theading for bolts. I will make up a protoype and post a pic. It will need to be a substantial fitting however, if it is to do justice to a 12" arm such as the SME.

[jrhymeammo]

Gdg,
I have sketched out a couple of design options on my CAD system, One of which fits into the existing arm well and clamped into the three holes. This does not involve any additional drilling of holes and theading for bolts. I will make up a protoype and post a pic. It will need to be a substantial fitting however, if it is to do justice to a 12" arm such as the SME.

Hey Mike,
This sounds really exciting!!
I would love to know the details of a prototype when available.

Thanks
JRA

[Mike_New]

JRA and Gdg,

I have now completed an evaluation of the options for a 12” adapter for the SL1200, using my profesional CAD system and have decided that a design, which locks into the existing arm well and fits over the back edge of the Chassis is the way to go. The adapter plate protrudes 130mm out from the back edge of the SL1200. The arm centre is 25mm to the left of the arm-well centre and 165mm towards the rear. It will be manufactured from 25mm thick engineering quality alluminium bar stock. The mounting level for the SME arm slides will be 15mm below the top surface of the SL1200 chassis. The thickness of the rear mounting plate section will be 25mm.

The slot will be angled at 23.6deg to the theoretical angle of the line extended from the spindle to arm pivot point in order to maintain SMEs cartidge offset angle when adjusting for position. Given these dimensions, the top of the adapter plate, which protruded out to the rear will sit approximately 15mmm above the top of the chassis surface.

Now given that most of you will probably be using an arm of this quality with my new Platters, which sit approx 2mm above the existing platter. My question is for those who have a 12” arm, will there be sufficient clearance under the arm to clear the adapter plate when seated in it’s installed position.??

I make no excuse for the solidity of this adapter plate, it has to be, to avoid any resonances. To quote from a paper by SME the arm plate should be of the utmost rigidity to absorb any vertical vibration arising from the excellent stiffness of the arm design generally.

[Gdg]

Mike,
I planned to get your platter, but so far I don't have any 12'' tonearm yet, and no idea of what to get. I could get the SME 312, but I do prefer a replaceable headshell tonearm such like the SME M2-12R or the Jelco SA-750TE 12". I'm expecting that you and Dave Cawley give me/us some advice about the best combo.
Thank you

[Mike_New]

I personally am not keen on replaceable headshells which presumes a screwed thread attachment. If you have seen a cross section of a screwed mating thread you would not be so keen!! The average thread only engages for about 75% of it's depth, and of course engages only on the pressure side! this is why water pipes alway leak without sealing tape!!. Only precision ground theads in high quality carbon steel really qualify for acceptance from a sonics point of view. and these are not to be found on the ends of Jelco or even SME arms to my knowledge.