Triplanar RCA out to Balanced out for MP-1

The turntable/arm ground wire should be used as the XLR ground.The +/non-inverted and the -/inverted signal will go to the respective terminals on the XLR,as these are floating +/-.

Dear Atmashere and Tpsonic, I am thankful for the advice but,alas,I am not capable to move in the opposite direction at the same time. Something that according to physics and logic is not possible. So I still have no idea
what to connect to pin 1: according to Atmasphere both(the shield as well as the ground wire);according to Tpsonic only the ground wire. But I still dont know which of all
are connected to the arm-mass.The shield or the ground-wire or both? Then,you see,I will know what to connect to
pin 1.
BTW I think I should look for a different hobby.

Regards,

Nandric, Try it both ways and see what happens. The very worst that can happen is hum; no risk of damage to anything except maybe your speakers if the volume is turned up too high. I own a Triplanar which I converted to XLR jacks from RCA jacks. I connected the shield to pin1. (I presume you know that hot from the RCA jack goes to pin2 and ground from the RCA jack goes to pin3.) I did not connect the tonearm ground wire to anything. It just hangs in the breeze. There is no hum. I've been using it this way for several years and with two or three different cartridges. If you DO get hum, just revise the ground connections, and you are likely to defeat the problem.

Interestingly, I converted my RS-A1 tonearm to straight thru balanced connection, for use with my MP1. I eliminated the female RCAs at the base of the tonearm and ran about 3 feet of Cardas wire straight from the cartridge pins to the preamp with XLR jacks. Once again, I connected the shield to pin1, but in this case I did have a hum problem which was eliminated when I grounded the body of the RS-A1 to the MP1 chassis.

Dear Lewm,Not everyone is as fearless as you are.But if I blow up my loudspeakers (those are my 'babys') I will kill myself or be killed by flying pieces of beryllium.I own the
Usher BE-20. So this hobby of my is literally toxic and, regarding my bank-account,also insane.
But if your Triplanar is also 'model' VII then I know what to do.
'Interesting',to use your expression,the former model VI(?)
has visible shield connection with the arm-mass.
Thanks and regards,

Nandric,
If you are unwilling to attempt a rewire and intend to keep the components you now have (I'm a happy AtmaSphere MA-1 amp owner and LOVE the sound!), I suggest you contact Albert at Space Tech Labs about adding one of his tube buffer/RCA-balanced converters.
My phono stage is single ended in/out. As well, the turntable and phono stage are both on a side wall stand, 10 feet from my line stage. The line stage is balanced in/out for best use with the Atma amps.
I bought Albert's "BUF-101", which is both buffer and RCA-balanced converter, as I have many spares of the tubes it uses (6X5 and 6L6).
Bottom line: I connect a 0.5m RCA pair from phono stage to the "BUF-101" RCA input, and use a 4m balanced (Mogami) cable pair into my line stage. The "BUF-101" is sonically transparent and I have no hum, despite the long XLR cable run that crosses several power cables en route to the line stage. I'd previously tried RCA-XLR adapters - hum city! I love the way my analog source now sounds.
The "BUF-101" costs a bit over $500USD and Albert may may recommend a less expensive of his converters for your particular application/gear.
This option only puts a bit of cash at risk.
Just my 2 cents...