Tonearm for Ortofon SPU-A cartridge

[shakti]

Hi, I am researching my options for a 12" tonearm for a Thorens TD124 restoration and have narrowed the decision to the Sorane TA-1L or the Groovemaster II. I see you have the Sorane, and just wondering if you have any experience with the GM, and if so how they compare? And should I be considering the Woody as well? Thank you.

I had not yet the chance to compare TA-1L and Groovemaster II with the GM.
Please have in mind, that the Sorane is 12,7" length, which does not fit every turntable.

 

[Walnut Horns]

I had not yet the chance to compare TA-1L and Groovemaster II with the GM.
Please have in mind, that the Sorane is 12,7" length, which does not fit every turntable.

Have you tried an SPU on your Glanz? Apparently, that tonearm was designed with the SPU in mind. Thanks.

 

[McDee275]

After using a Schick 9'6 with an Ortofon APJ-1 for some time to fit my Ortofon SPU Wood A, I finally decided to buy me a new tonearm matching the SPU A better.

Using now a GrooveMaster III, especially made to fit Ortofon SPU A cartridges.




The 12" GrooveMaster is, imhO, a better match to the SPU A cartridges as the 9'6 Schick with APJ-1 adaptor.

 

[Don_Camillo]

Thanks for the suggestions. I have the APJ-1 adapter, but think #2 may be better because using an adapter might degrade the sound. Do you know the general sound charateristic of the Sorane TA-1L? Even though I'd like to try a modern tonearm, I still would like to have warm/full/big sound. Thanks!

Nope, this option (#2) is no good idea because it´s far away from original geometry with high impact on distortion characteristics.

 

[Don_Camillo]

I have been using it with a vintage Ortofon RF-297 and want to try a modern tonearm.

Please take into your account that the RF-297 applies tracking force dynamically to the needle, what´s the absolut best solution in order to reduce tracking distortions. All modern tonearms you put on your list are statically balanced. Thus the RF-297 is still the much more modern and also more technically advanced concept.

 

[Shuggie]

After using a Schick 9'6 with an Ortofon APJ-1 for some time to fit my Ortofon SPU Wood A, I finally decided to buy me a new tonearm matching the SPU A better.

Using now a GrooveMaster III, especially made to fit Ortofon SPU A cartridges.


View attachment 94985

The 12" GrooveMaster is, imhO, a better match to the SPU A cartridges as the 9'6 Schick with APJ-1 adaptor.

A very good choice!

 

[jeannyp]

After using a Schick 9'6 with an Ortofon APJ-1 for some time to fit my Ortofon SPU Wood A, I finally decided to buy me a new tonearm matching the SPU A better.

Using now a GrooveMaster III, especially made to fit Ortofon SPU A cartridges.


View attachment 94985

The 12" GrooveMaster is, imhO, a better match to the SPU A cartridges as the 9'6 Schick with APJ-1 adaptor.

VERY nice!! Thanks for sharing!

 

[miniguy]

Nope, this option (#2) is no good idea because it´s far away from original geometry with high impact on distortion characteristics.

Not so. Do the math.

 

[Don_Camillo]

Not so. Do the math.

Yeah, of course I´ve done that. Distortion is the issue because of a gemetry that doesn´t fit anymore to the tonearms design.

 

[jeannyp]

Yes. If you want to use the TA-1L, you have two options:

1. Buy a Ortofon APJ-1 adaptor (https://www.ortofon.com/apj-1-adaptor-for-spu-a-houses-p-582) which allows an A-mount SPU to be used on regular arms like the TA-1L designed for 50-52mm mounting collar to stylus distance. The 6 gram weight of the adaptor will increase the effective mass of the arm by that amount, but shouldn’t be much of an issue with the low compliance Royal.

2. Move the TA-1L closer to the spindle to compensate for the 21.5mm difference in mounting collar-to-stylus distance between A-mount and G-mount SPU. The correct amount is determined by some fairly simple geometry. You end up basically with the arm having a new effective length as well as offset angle. This is how I run the SPU Wood A on my Ortofon RS-309D tonearm.

If you want to try option 2, I will be happy to give you the optimum pivot-to-spindle distance and overhang. I would need to know the effective length of the TA-1L and its offset angle.

Hi I recently obtained a vintage Ortofon RMG-309 tonearm and would like to try my vintage SPU-A cartridge without the APJ-1 adaptor. I would appreciate it if you give me the optimal setting for this combination. Thank you!

 

[miniguy]

Hi I recently obtained a vintage Ortofon RMG-309 tonearm and would like to try my vintage SPU-A cartridge without the APJ-1 adaptor. I would appreciate it if you give me the optimal setting for this combination. Thank you!

The RMG-309 null points are 60.0/115.4. If you want to maintain these same null points then with the SPU-A, you should set your pivot-to-spindle distance at 287.6 mm. This gives an overhang of 11.8 mm.

 

[jeannyp]

The RMG-309 null points are 60.0/115.4. If you want to maintain these same null points then with the SPU-A, you should set your pivot-to-spindle distance at 287.6 mm. This gives an overhang of 11.8 mm.

Great! Thank you very much! I will try that. In the meantime, I was wondering if you could share your calculation in a bit more detail so that I can apply your method to other tonearms. You can PM me if you prefer. Thank you very much again!

 

[miniguy]

Great! Thank you very much! I will try that. In the meantime, I was wondering if you could share your calculation in a bit more detail so that I can apply your method to other tonearms. You can PM me if you prefer. Thank you very much again!

L? = (L?² + D² ? 2L?D cos?)½ , Arm effective length with A-style SPU
? = arcsin (L? sin? /L?) , Arm offset angle with A-style SPU
L? = Arm effective length with G-style SPU
D = 21.5 mm difference between SPU-G and SPU-A mounting collar to stylus distance
? = arm offset angle with G-style SPU

Use the solutions to L? and ? as inputs to the Tonearm Alignment Calculator on vinylengine.com to determine the correct overhang consistent with your desired alignment goal, e.g., maintain same null points or go for minimal error at inner grooves or something else. This requires some iterative calculations.

 

[jeannyp]

L? = (L?² + D² ? 2L?D cos?)½ , Arm effective length with A-style SPU
? = arcsin (L? sin? /L?) , Arm offset angle with A-style SPU
L? = Arm effective length with G-style SPU
D = 21.5 mm difference between SPU-G and SPU-A mounting collar to stylus distance
? = arm offset angle with G-style SPU

Use the solutions to L? and ? as inputs to the Tonearm Alignment Calculator on vinylengine.com to determine the correct overhang consistent with your desired alignment goal, e.g., maintain same null points or go for minimal error at inner grooves or something else. This requires some iterative calculations.

Thank you very much! I will play around with this. Really appreciate it.