Tonearm for Technics SP-15

Plinth is Technics SH-15B3.

Plinth manual says arm lengths: spindle to arm pivot (sap): 206 to 235 (sap = effective length minus overhang)

rear portion of arm: for 206 sap is max 110mm; for 235 sap is max 97

https://www.vinylengine.com/library/technics/sh-15b3.shtml

• is designed without its own plinth, like the SP-10.

this is not correct, for the SP10 you need at least a 10.5 "arm any other arm below that size would be too short and at rest it would remain bent towards the platter.

my friend has a unit in a plinth with a dust-cover. it looks like OEM Technics to me, I could check. Grace arm is in a circular removable board, also looks OEM, with a long oval cutout for various lengths.

removable arm board looks like this

(seller says fits 9 or 12 sme arms

That one looks like an SME cutout. Several arms use that mounting- it allows the arm to be moved to get the right geometry.

Yes, I have an SME 3009, sliding plate, but no VTA on the FLY.

I found a GST-1 just listed in New Zealand, sliding plate with VTA on the Fly, and magnetic anti-skate

I'm pretty sure it will fit his SP15 Plinth, would need to confirm the rear length and height.

seems to be a good price

just for the record, both technics EPA-100 and EPA-250 are 235mm + 15mm overhang = 250mm effective length, the maximum length for the SP15 OEM bases.

that's 9-7/8" effective length.