How do I know if a tonearm fits my turntable?

[DoctorJEB]

Having not owned a turntable in 45 years, I have what may be a very newbie question.

I just acquired a Thorens TD 160 Mk I with the standard TP16 tone arm (effective length 230 mm, mounting radius 215.60 mm, 14.4 mm overhang, 22.00 degree tonearm/headshell angle, 16.5g effective mass). The table is in mint condition, both cosmetically and mechanically (motor is perfect - platter bearing looks like new).

Unfortunately, I would like a low mass tonearm like the Thorens TP16 Isotrack tonearm that came in many later versions of the TD 160 Mk II turntable. (It would match well against my old Micro-Acoustics 2002e, a 4g cartridge of unknown compliance but legendary for its very high compliance and known to love tonearms in the 7 to 9 gram effective mass range.) How do I know if a tonearm I buy (e.g., on Ebay) will fit?

I am looking at an Isotrack tonearm body with a TP63 headshell wand which has similar but not identical specs, the difference being that the effective length is 232 mm. (The TP62 headshell wand renders the effective length at 230.00 mm.) Can I swap these arms? Is the key spec the mounting radius of 215.60 mm? Isn't it better to have a longer effective length (resulting in lower tracking error)? Is the effective length of 232.00 mm with the TP63 tonearm wand a real issue about which I need worry?

 

[Sgt Shultz]

Having not owned a turntable in 45 years, I have what may be a very newbie question.

I just acquired a Thorens TD 160 Mk I with the standard TP16 tone arm (effective length 230 mm, mounting radius 215.60 mm, 14.4 mm overhang, 22.00 degree tonearm/headshell angle, 16.5g effective mass). The table is in mint condition, both cosmetically and mechanically (motor is perfect - platter bearing looks like new).

Unfortunately, I would like a low mass tonearm like the Thorens TP16 Isotrack tonearm that came in many later versions of the TD 160 Mk II turntable. (It would match well against my old Micro-Acoustics 2002e, a 4g cartridge of unknown compliance but legendary for its very high compliance and known to love tonearms in the 7 to 9 gram effective mass range.) How do I know if a tonearm I buy (e.g., on Ebay) will fit?

I am looking at an Isotrack tonearm body with a TP63 headshell wand which has similar but not identical specs, the difference being that the effective length is 232 mm. (The TP62 headshell wand renders the effective length at 230.00 mm.) Can I swap these arms? Is the key spec the mounting radius of 215.60 mm? Isn't it better to have a longer effective length (resulting in lower tracking error)? Is the effective length of 232.00 mm with the TP63 tonearm wand a real issue about which I need worry?

Keep in mind the total weight of the arm assembly will need to be supported by the TT suspension and it's tuning will be affected. Not saying it can't be done, just something to consider when choosing the new arm.

I had to rebuild or change the arm on my AR XA, I was lucky enough to stumble on a perfect donor from a vintage Sony deck. Installed so reinstalling the original would be possible.