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LP-12 Naim Aro Owners Please Read

So you're saying Nic's trig calculations are off? How so?
Maybe not but I am! As I said a while ago, my calculation uses a constant offset angle of 24° and this is correct for only one bolt-to-stylus and therefore effective length. I didn't know how else to work it out. I think I do now, so I'll be back with more when I've done it. I don't think the errors are great, but I don't know for sure.
 
My figures concur with Nic's.

Paul
(Obviously I rounded to just 2 dp.) Interesting that your figures are very close to, but not exactly the same as, mine. I suspect you haven't made the error/simplification that I did. I'll see what I get when I correct for that. :)
 
7.95 is what is required to fit the specs of 229 effective length and 24 degree offset, given the pivot-mounting hole distance from the drawings. 211 mounting then fits nicely with Baerwald and matches the specified 18mm overhang. Everything fits together.

If you have 212.5 spindle-pivot then you want an effective length of 230.51mm and offset of 23.915 degrees. Which you obviously can't get close to with any cart. But my table will let you see how far away your particular setup is.

Paul
I'm in agreement with your figures but why can't you get close to this? The bolt-stylus is only 1.5 mm longer than the designed-for figure. Or do you mean that the offset can't be adjusted to suit?
 
Are we sure about the last point? Do we know for sure what the Linn cartridge bolt-to-stylus distance is?

I have an inquiry out there with Linn, I'll report back. I have a Troika and attempted to measure for myself but it's really hard to measure such a small amount like that with a ruler. I certainly don't want to have an accident and trash the thing. My best estimate is that it is either 7 or 8 mm.

I'll try to obtain bolt to stylus distances for other cartridges as well and will publish them when they arrive. This thread may as well be a repository for such information.

I still don't understand the discrepancy for the Naim Aro specs. Google Naim + Aro + 212.5 and you'll get a ton of hits including current Naim brochures and reviews of the Aro.

I'd also like to see a spec for the third cartridge bolt to pivot distance for the Aro vs Ekos to see if they are the same.
 
I have an inquiry out there with Linn, I'll report back. I have a Troika and attempted to measure for myself but it's really hard to measure such a small amount like that with a ruler. I certainly don't want to have an accident and trash the thing. My best estimate is that it is either 7 or 8 mm.

I'll try to obtain bolt to stylus distances for other cartridges as well and will publish them when they arrive. This thread may as well be a repository for such information.

I still don't understand the discrepancy for the Naim Aro specs. Google Naim + Aro + 212.5 and you'll get a ton of hits including current Naim brochures and reviews of the Aro.

I'd also like to see a spec for the third cartridge bolt to pivot distance for the Aro vs Ekos to see if they are the same.
Thanks. It's very hard to measure any of this stuff, isn't it? I've tried measuring my Ekos's pivot-to-outer-bolt (with Arkiv fitted, when the 3rd bolt fixes the 2 front bolts in the slots) but gave up. I can't imagine how I'd even try getting the bolt-to-stylus figure for the Arkiv with anything like useful accuracy.

The 211/212.5 (and matching effective lengths) discrepancy puzzles me too, which is why I first tried to find out if the arm itself changed at some point. It seems not.
 
I'm in agreement with your figures but why can't you get close to this?
When you put an alternative cartridge onto an ARO you get a new effective length and offset. These values are not optimal for any mounting distance, you can have one or the other nearly right, but not both.

I think it is clear that the 212.5 mounting distance is an error, whatever its source.

Paul
 
I think it is clear that the 212.5 mounting distance is an error, whatever its source.

Paul

That's been evident from the very beginning of the thread, but some contributors won't let that go, despite the official drawings being displayed, plus confirmation (at second hand) from the designer.
 
That's been evident from the very beginning of the thread, but some contributors won't let that go, despite the official drawings being displayed, plus confirmation (at second hand) from the designer.

I could hardly agree more.
 
That's been evident from the very beginning of the thread, but some contributors won't let that go, despite the official drawings being displayed, plus confirmation (at second hand) from the designer.

I couldn't agree more.


I'll try to obtain bolt to stylus distances for other cartridges as well and will publish them when they arrive. This thread may as well be a repository for such information.

I would personaly find this information interesting as very few manufacturers seem to publish it. However, I would suggest it would be better placed in the reference section as it will be lost within the Möbius loop that is this thread, IMHO.

I still don't understand the discrepancy for the Naim Aro specs. Google Naim + Aro + 212.5 and you'll get a ton of hits including current Naim brochures and reviews of the Aro.

This hardly surprises me. A/ It is easy to repeat information found on the web, especially if one assumes it comes from a position of authority. B/ Few people can be bothered to actually check the validity of stated data, or do any research beyond Google. C/ Mistakes happen.
 
The AT33PTG measures 8mm and is specced at 9mm. Perhaps this reflects the displacement of the suspension when in use.

Paul
 
At least these have been published by the manufacturers:

Audio Technica AT-33EV - 9mm
Audio Technica AT-33PTG - 9mm
Audio Technica AT-33PTGII - 9mm
Audio Technica AT-OC9 -9,3mm
Denon DL-103R - 7,5mm
Dynavector DV-20X2L - 8,5mm
Dynavector DV-20X2H -8,5mm
Dynavector 17D3 - 8,5mm
Dynavector XX2 MkII - 8,5mm
Dynavector Te Kaitora Rua - 8,3mm
Dynavector XV-1s - 8,0mm
Dynavector XV-1t - 8,0mm
Lyra Argo - 9,5mm
Lyra Dorian - 9,5mm
Lyra Delos - 9,5mm
Lyra Kleos - 9,5mm
Lyra Olympos - 9,5mm
Lyra Skala - 9,5mm
Lyra Titan - 9,5mm
Lyra Clavis - 7,8mm
Lyra Helikon - 7,8mm
Lyra Helikon SL - 7,8mm

Br,
Teme
 
When you put an alternative cartridge onto an ARO you get a new effective length and offset. These values are not optimal for any mounting distance, you can have one or the other nearly right, but not both.

I think it is clear that the 212.5 mounting distance is an error, whatever its source.

Paul
Yes, meaning that an effective length of 230.5 is also an error.
 
At least these have been published by the manufacturers:

Audio Technica AT-33EV - 9mm
Audio Technica AT-33PTG - 9mm
Audio Technica AT-33PTGII - 9mm
Audio Technica AT-OC9 -9,3mm
Denon DL-103R - 7,5mm
Dynavector DV-20X2L - 8,5mm
Dynavector DV-20X2H -8,5mm
Dynavector 17D3 - 8,5mm
Dynavector XX2 MkII - 8,5mm
Dynavector Te Kaitora Rua - 8,3mm
Dynavector XV-1s - 8,0mm
Dynavector XV-1t - 8,0mm
Lyra Argo - 9,5mm
Lyra Dorian - 9,5mm
Lyra Delos - 9,5mm
Lyra Kleos - 9,5mm
Lyra Olympos - 9,5mm
Lyra Skala - 9,5mm
Lyra Titan - 9,5mm
Lyra Clavis - 7,8mm
Lyra Helikon - 7,8mm
Lyra Helikon SL - 7,8mm

Br,
Teme
That's a good start. Thanks.
 
Yes, meaning that an effective length of 230.5 is also an error.
I'm not sure what you mean. If you mount a cart with a stylus-bolt distance of 9.5mm in an ARO then it now has an effective length of 230.5mm wherever you choose to mount it.

Paul
 
A few more from Ortofon:

Ortofon 2M series - 9,5mm
Ortofon Vivo series - 10,6mm
Ortofon Rondo series - 7,0mm
Ortofon Cadenza series - 9,5mm
Ortofon MC Windfeld - 9,5mm
Ortofon MC20 Super - 8,5mm

Br,
Teme
 
A cartridge value of 9.6mm gives you an effective length of 230.5 and an offset of 23.83. Or you find a cartridge with 8.75mm giving an effective length of 229.73 and offset of 23.919. The point is that you cannot make it right by moving the arm base. Puts me right of SME arms.

Anyway if you look at the consequent distortion plots I think 211mm mounting with a 9.6mm cart is a much better compromise than a 212.5 mounting with a 7.95mm cart. If you have a Greenstreet at 212.5mm then you really don't want to be using a Linn sized cartridge (assuming Linn sized is about 8mm, which AFAIK, isn't confirmed)

Anyway I assume Greenstreet have fixed this now.

Paul
The GreenStreet Audio site still has a page referring to 212.5 being in the Aro spec, along with instructions to remove some of the LP12's corner brace. How long has this been now? I think this thread started in 2009.
 
When you put an alternative cartridge onto an ARO you get a new effective length and offset. These values are not optimal for any mounting distance, you can have one or the other nearly right, but not both.

I think it is clear that the 212.5 mounting distance is an error, whatever its source.

Paul

I'm not sure what you mean. If you mount a cart with a stylus-bolt distance of 9.5mm in an ARO then it now has an effective length of 230.5mm wherever you choose to mount it.

Paul
We agree that 212.5 is wrong for the Aro. We also agree that 230.5 is correct for 212.5. Therefore if one is wrong, then the other is too.
 
We agree that 212.5 is wrong for the Aro. We also agree that 230.5 is correct for 212.5. Therefore if one is wrong, then the other is too.
Quite.

212.5mm pivot-to-spindle and 230.5mm effective length produces a near perfect Baerwald alignment. So, if a suitable cart is used to produce a 230.5mm effective length on an ARO on a 212.5mm GS sub-chassis, how is it "wrong"?
 
By accident the Greenstreet/ARO subchassis produces acceptable alignment with long cartridges. These are not the same cartridges that produce good alignment with the Linn subchassis/armboard. This matters. If you try a Linn sized cartridge with a Greenstreet/ARO you get a very poor alignment, rather worse than if you use a 'long' cart with the ARO intended mounting distance.

And anybody moving an LP12/ARO from a Linn subchassis to a Greenstreet will get a change in alignment which will obscure the contribution of the subchassis. Which is a shame.

Paul
 
Quite.

212.5mm pivot-to-spindle and 230.5mm effective length produces a near perfect Baerwald alignment. So, if a suitable cart is used to produce a 230.5mm effective length on an ARO on a 212.5mm GS sub-chassis, how is it "wrong"?

Yes those are correct for one another but not for the Aro, which was designed with a shorter geometry and therefore has a different offset. This should be clear if you read the comments in this thread. You need all 3 to be consistent for optimum alignment.
 


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