Turntable advice / opinion on setup / sound.

@lewm 

This offset angle ranges from about 20 to 22 degrees for a 9 or 10 inch arm, less for a longer arm.  That automatically results in an angular error equal to headshell offset and causes a skating force that is always directed inward

I do have a 9-inch SME Series II improved tonearm with fixed headshell and thread-and-weight anti-skating device in addition to the Holbo, so this topic is of practical as well as theoretical interest to me.  If the SME thread falls off its wheel and runs on the axle, the result is very audible!

It bothers me when you refer to the headshell offset angle as an angular error. In fact, it is designed to reduce the angular error between groove and cartridge to as close to zero as possible, within the geometrical constraints of a pivoting system.  Properly set up, there are two points during play where the angular error is zero, Outside these points, the error is under 2-degrees, not around 20-degrees as you imply.

The original calculations were set out by Percy Wilson, then the technical editor of The Gramophone magazine, about 100 years ago.  Before then, Percy invented and I believe patented a linear tracking ’tonearm’.  About 6 feet long, and floating on two mercury baths, the arm directly carried a 6-foot horn loudspeaker made of lightweight papier mache.

The physics is straightforward if you concentrate of the line between the pivot and the stylus - skating forces arise when the record groove moving under the stylus does not align with the line.

An A(nti) S(kating) device applies a force near the pivot to counteract skating that occurs at the stylus tip.  This puts a constant tension on the cantilever.  That tension cannot be a good thing

The ideal antiskating force exactly balances the skating force at the stylus, so the overall suspension is unstressed (surely a good thing).  The stylus experiences exactly opposite skating and anti-skating forces (also a good thing).  The cantilever during play experiences stretching tension from the friction between stylus and record groove which, being made of rigid aluminium, boron, diamond or whatever, it is designed to handle.

There is a continuum for pivoting tonearms from ideal overhang (minimises maximum tracking error) to reduced overhang all the way through various degrees of under-hang.  

The Stereophile review suggests that under-hung tonearms significantly increase distortions which may please some ears.

That’s why I would like you to experience a Holbo, which gets the geometry right and uses the friction-free principle pioneered by Percy’s mercury bearings!

@richardbrand 

I do have a 9-inch SME Series II improved tonearm with fixed headshell and thread-and-weight anti-skating device in addition to the Holbo

I assume you realise that because the SME series II has non offset vertical bearings, whenever the arm is not parallel to the record the azimuth is out and you are probably damaging your records.

With any arm that has non offset vertical bearings and an offset cartridge ( this covers most vintage tonearms ), any time you adjust VTA the azimuth goes out.  ( cartridge is now leaning to one side.  ).

To see this for your own eyes put a bubble level on the headshell and then adjust the VTA - you will be shocked at how much the cartridge rolls and leaves the azimuth out by some margin.

@dover 

You'll have to help me with some terminology here!  What do you mean by vertical bearings?  I don't think you mean the bearings in the pivot that allow the arm to rotate in the horizontal plane?  The other bearing is a knife edge bearing where the knife edge itself is horizontal, allowing the cartridge to lift vertically.

In reality, I have only adjusted the arm height when changing cartridges, or when I changed the thickness of the platter mat.  Changing the arm height is not the best feature of the SME.  I use a reticulated scale to get the arm parallel to the record surface.

The azimuth roll you describe should also be obvious when lifting the arm to cue it.  I'll have a look next time I am home, but my instinct is that the knife-edge bearing is parallel to the cartridge face?  In that case, my brain is not wired to understand how the cartridge rolls 

@dover 

I’ve just had a look at a picture of my SME and my recollection was wrong - the knife-edge bearing is not parallel to the cartridge face, so I agree about azimuth roll.  The bearing is at right angles to the arm at its base, but the arm then bends.

Although the headshell is described as fixed, it is designed to allow some rotation to adjust azimuth, which is a simple adjustment.

I was probably thinking of an earlier Garrard arm ...

@elliottbnewcombjr

"Apple and Rega may make terrific products, they are both proprietary greedy, neither one will get a dollar from me."

Comparing Rega to Apple is absolutely absurd! Rega is a tiny little company that supports other tiny businesses in it's region as well shares engineering knowledge with them as well as capitalization for R&D and tooling so Rega has a reliable source for the proprietary ingredients they use in their products. This benefits the local economy and provides good paying jobs and benefits there. Rega is a wholly private entity self-funding and supported and is not publicly supported in any way other than revenues generated by it's own enterprise. You should thank them on your hands and knees for their endeavors, or you wouldn't be having this discussion in the first place!