Tone arm length

I almost forgot about the microscope.  We are summering at our home in New Hampshire.  The microscopes are both at our winter home in Florida.  If you are really interested send me a private note and when we get back in late September or thereabouts I'll send you photos and we'll take it from there.

@billstevenson

Nice! Thanks Bill, will do.

I lived on the island from 1971 to 1992. My first visit to sound hounds was around 1980 .It was a bit dingy - geeky back then but super cool. Had all the MAC stuff including their first CD player. Looks like it's had a refresh but still in business AND in the same location which is amazing.

Hi Mac,

The shorter arm is ALWAYS going to be better for several reasons which always are going to be more significant than any benefit from marginal improvement in tracking error. The shorter arm is stiffer. It takes more energy to get it to resonate or looking at it from the other direction it is better at holding the cartridge still. The shorter arm has a lower moment of inertia. It follows the record more effortlessly interfering less with the cartridge. The shorter arm has a lower effective mass allowing it to work perfectly with more cartridges. You can always add more mass if you need it, but it can be very difficult to remove mass. 
 

Some very respected turntable manufacturers like Basis and Sota do not even give you a choice. Many very smart engineers look at 12 inch arms as being foolish. If they make them at all it is only to satisfy customer demand so as not to lose business. 

Some very respected turntable manufacturers like Basis and Sota do not even give you a choice. Many very smart engineers look at 12 inch arms as being foolish.

Although Basis does offer its TOL SuperArm as 12.5" and 16". And Origin Live, while acknowledging the downsides of longer arms, still says it prefers the 12-in sound of its arms. So sonic preferences, the final arbiter, do play a part.

OTOH, Bob Graham famously said the 9-in arm was his best sounding, and many people say the 9-in is the best sounding 4Point.

I’m about the install a 12-in Phantom on the same turntable as a 9-in for the first time, which should make for an interesting comparison.

I’ve spoken at length about this topic with two audio pioneers who are some of the most knowledgable people on the planet when it comes to vinyl reproduction.

George Merrill (whom I assume needs no introduction here) strongly prefers 12-inch arms for the most obvious reason: geometry. If you focus on optimizing cartridge alignment, a longer arm is clearly superior when it comes to things like optimizing the placement of null points.

But JR Boisclair of WAM Engineering (that’s "Wallytools") disagrees that this benefit outweighs the real-world performance benefits of a shorter arm. For those not familiar with WAM, JR is known for his years of extensive testing and analysis of arm & cartridge characteristics. Sure, resonances & whatnot are factors to consider, but qualitative factors don’t automatically translate into quantitative differences in performance. If a cartridge is properly aligned -- something that JR insists must be done by means of microscopic analysis -- arm bearings become a crucial factor. JR has found that too-loose or too-tight bearings may be the most important cause when an otherwise good arm exhibits a lot of mistracking. (He even sells a WallyTool that checks bearing play.) And he’s found empirically that a 9-inch arm, all things equal, will almost always be more stable than an equivalent 12-inch model.

Me, I've always been in awe of George's expertise and still love the bespoke table he built for me many years ago. But I gotta say that JR is a brilliant engineer, is not given to hyperbole, and has a fanatical commitment to basing his conclusions on high-precision empirical measurements. So when I upgrade to a Hana Umami next month (after my unit has been analyzed by WAM, of course), I’ll probably be picking up one of George’s 9-inch arms to go with it.