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Ortofon AS212 Effective Mass

L

lenko

New Member
Hi everyone!

I’m considering buying an Ortofon AS-212 tonearm to replace the original tonearm on my Lenco L75.

I’d like to use it with either a Nagaoka MP-300 or MP-500, and from what I understand those cartridges work best with a tonearm effective mass of no more than 12g.

According to the Ortofon brochure, the AS-212 has an effective mass of 12–18g depending on the counterweight position. My question is: does that figure include the original headshell?

If it does, would switching to a lighter headshell, say around 6g, bring the effective mass down enough to make this a good match?

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It should include the original headshell. Not sure how much that weighed, probably around 10g. The AS-212 has fairly typical mass for that kind of S-shaped arm, I'd say with a light (<8.5g or so) headshell it should be an OK match with the Nagaokas.
 
muovimies said:
It should include the original headshell. Not sure how much that weighed, probably around 10g. The AS-212 has fairly typical mass for that kind of S-shaped arm, I'd say with a light (<8.5g or so) headshell it should be an OK match with the Nagaokas.
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Thank you! When you say "OK match", do you mean it's still not ideal?
 
lenko said:
Thank you! When you say "OK match", do you mean it's still not ideal?
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Well I'm currently using an MP-500 stylus on a Sumiko MMT arm with a 6.5g headshell. This combination works fine, but with a 10g headshell it was starting to get a bit hairy. I think the MMT is slightly heavier arm than the AS-212, but not sure. I've owned both though not at the same time, so take this with a grain of salt but my impression is the AS-212 was probably a bit lighter.

So I think it's probably not "ideal", but the practical difference between ideal and OK is basically nothing under most circumstances. I mean ideally there would be no resonance at all at any frequency, so I guess "ideal" doesn't really exists to begin with, there's just varying levels of OK :) For example with the 10g headshell things were getting somewhat unstable when dealing with warps, which tells me the resonance frequency was getting too low and no longer quite OK. It was still usable and I'm not sure about the level of audibility of such issues - logic tells me it should cause intermodulation distortion both at the cartridge and (bass-reflex etc.) speakers as the cones are pumping trying to reproduce ~5Hz tones. A subsonic filter would relieve the speakers from that but at the cartridge end getting the resonance frequency higher is the only cure, though fluid damping can also help. Anyway, to my ears it still sounded fine even on slightly warped records, though visually it didn't look too good. Also if you buy the version that comes mounted on Nagaoka supplied headshells, those were always on the heavier side so apparently Nagaoka thinks nothing of it.

No such issues with a 6.5g headshell, so the 3.5g made all the difference. It was pretty much OK on a 8.5g headshell as well, so I feel pretty safe in saying it would be fine on an AS-212 with a light headshell.
 
Did some quick calculations and with a headshell in the 7 g range; both the MP 300 & 500 will work fine with an effective tonearm mass of 12 g.
 
For future reference, I contacted Ortofon support, and apparently the effective mass figures take the original headshell into account.
 
The cartridge is 8g and must be added to effective mass. The adjustable VTF range is stated for cartridges of 3g and 8g - meaning, the counterweight will be somewhere at the max. distance, resulting in approx. 18g effective mass of arm with headshell + cartridge 8g + screws 1g = ~27g.
 
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borchee said:
The cartridge is 8g and must be added to effective mass. The adjustable VTF range is stated for cartridges of 3g and 8g - meaning, the counterweight will be somewhere at the max. distance, resulting in approx. 18g effective mass of arm with headshell + cartridge 8g + screws 1g = ~27g.
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Yes, but that’s with the original headshell, which weighs about 10 g. A lighter headshell, say 6 g, would drastically reduce the effective mass, since it reduces the weight at the far ends of the tonearm. But I read conflicting compliance figures for Nagaoka MP-500. If I'm to believe these measurements (~30 cu), then I'm going to need a tonearm with an effective mass of ~6 g, ideally, which is as low as it can get. On the other hand most people online say <12 g should be fine for the Nagaoka, which the AS-212 with a light headshell is.
 
lenko said:
Yes, but that’s with the original headshell, which weighs about 10 g. A lighter headshell, say 6 g, would drastically reduce the effective mass, since it reduces the weight at the far ends of the tonearm. But I read conflicting compliance figures for Nagaoka MP-500. If I'm to believe these measurements (~30 cu), then I'm going to need a tonearm with an effective mass of ~6 g, ideally, which is as low as it can get. On the other hand most people online say <12 g should be fine for the Nagaoka, which the AS-212 with a light headshell is.
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You can test here. Nagaoka has dynamic compliance of 20-22 and static compliance of 8.5 at 100 Hz.

Tonearm LF Mechanics

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