9" or 12" tonearms -- any sound difference?

I'm curious about others' experiences of comparing 9" and 12" tonearms with, say, Shure mm cartridges.

After living with a 12" 3012 arm for some time, I've just reverted to a 3009 arm and I can't honestly hear a loss of quality. I want the 12" to sound better, but I can't say that it does really. Maybe the 12" magic is with less compliant carts like the Denon 103 or even SPUs?

I think in your case where the arms are of similar flavors it will be harder to initially tell the differences but if you live with the 9" arm for a while and revert back, you might notice a more refined presentation due to the 23% (there about) less angular groove distortion. Also if you moved up to some more refined modern carts the difference would be more revealing. The 3012 and 3009 though excellent in their day and still not bad today will not show the difference as much as a more modern product as bearing and wire technology is so much more advanced. It will be these areas coupled with more refined and expensive carts that will show up the differences between a 9" and 12" arm.

12" tonearm has less inner groove distortion and better tracking.

A compromise would be a 10" tonearm.

10" OK but not quite as fine as the 12" tonearms. One major reason why broadcasters kept on buying them was superior tracking on the inner grooves. Even after 16" discs became out of usage.

Depends on what you're running cart-wise. Very few 12" arms are best with higher compliance carts. Most 12"ers have too much mass and high moment of inertia. With longer length is also a greater time lag between tip and bearings. Both Magnapan and Sonus investigated this in their low mass designs and settled on 240mm as optimal eff length. If you look at tracking angle error in degrees rather than a percentage, the difference doesn't seem as great. It also depends on alignment. 12"ers tend to have greater resonance and less rigidity, depending on design.

Beside reduced tracking angle error, 12"ers will have less variation in VTA/SRA with warps, than shorter arms. A high quality design certainly can sound good with low cu carts like the 103. I believe there are now some lower mass 12"ers. Maybe Moerch? I've found that many med/high cu carts sound sluggish in higher mass arms regardless of length.
neo

I have owned the Jelco 750D 9", 750DL 12" arms Not on the same TT but with the same DL-103D cart. and I can't say that I have a heard a major difference. But geometry wise the 12"er has better specs as far as tracking angle and VTA...

Thanks for the thoughts so far. When you've been mulling this around in your head, it's good to get some fresh views and experience. I'm running a Shure V15III on these tonearms and I'm sure the high compliance is a factor.

I have had newer arms, Helius Aureus and Rega RB250 with all the tweaks and I'm staying with SME for serviceability, looks and sound.

If 12" arms are better, why didn't they catch on? Footprint of the tt was an issue?

KentTeffeteller said:

12" tonearm has less inner groove distortion and better tracking.

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In my view, both (9" and 12") have sufficiently low tracking distortion to make the difference irrelevant.

Note that tracking is not a function of arm length, and inner groove distortion is usually caused by other factors than arm per se.

When we switch from 9" to 12", what is mainly changing is the effective mass and the inertia; most sound differences can be atributed to this, assuming all else (arm bearings, tube material, etc) is equal.

There's also, in theory, reduced warp-wow too.

One thing hat folk will say as a negative about a 12" arm is it's lack of rigidness compared to a 9" or 10" arm.

Another, and this can be perceived as a neutral or a positive as well, depending on your view, will be the added weight (thus added mass/inertia) of a 12" arm over a 9" or 10".

Positives are a reduced tracking angle error and a reduced variation in VTA due to arm length, and a reduction in inner groove distortion.

So, with the plusses, also come some minuses, as with almost everything else in life.

and the differences are minute.

I don't fret it. Whether I am running a 9" arm or a 12" arm or something in between, they'll all perform wonderfully.

Currently my collection of arms is primarily 237mm and 250mm arms. That's 9.33 inches and 9.84 inches, respectfully.

While attending Franks October Fest in Clinton MA this past weekend an AK member was demoing his Thorens TD-124 with a Grado wood tonearm that I believe was 12". He had a Stanton 681EEE cartridge installed. My guess is a Denon DL-103 would also work quite well on the Grado wood tonearm that should have some heft/weight to it.

The only thing that might be positive is the decrease in offset angle. This in turn will improve tracking, especially at inner grooves. For a normal Baerwald it´s about minus 6deg, that will most certainly improve tracking.

But there are many negative factors.

gusten

gusten said:

The only thing that might be positive is the decrease in offset angle. This in turn will improve tracking, especially at inner grooves. For a normal Baerwald it´s about minus 6deg, that will most certainly improve tracking.

But there are many negative factors.

gusten

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I think you're right.

Thanks for these further thoughts. They would explain why the SME 3009 Improved sounds so good with the Shure V15III.

One of the 12" arms I use is a hybrid SME. It has a hardwood central piece which is meant to damp resonance and is a bit lighter than the other 12" stainless steel one. These longer arms are enjoyable to use, but it's partly just 'the look'.