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Math to show WHY under-hang tonearms sound superiors

ripblade said:
Yes, but the cure (AS) *is* a constant. See the problem there?
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Well...no, I don't. An externally applied constant anti-skating force is intended to counteract (reduce) the average, across all positions of the stylus and for average vinyl, skating force. Obviously some net lateral force remains.

Is that a problem? Only if the remaining force is of practical significance and another approach is demonstrated to work better...without making other problems worse.

For the record, "physical reality" is not what Baerwald or Lofgren say it is---it's just what is.

Physical models rarely include terms describing the influence of say, the phase of the moon, but that does not mean there is no influence (such as by influencing, say, the gravitational "constant" g or even by introducing entirely new effects).

Such impacts may be demonstrated to exist in a given situation either experimentally or by generating a physical model that properly takes them into account. In either case, the effect may still be practically significant or not.

That said, everyone is free to align their TT(s) according to whatever approach(es) they prefer.
 
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Hi, Well I see we have at last made some progress.

- So many years ago straight arms where considered by Baerwald from Tchebychev calculations, they did not completely discount the design. Now you guys must realise that the performance of arms & especially cartridges have come a long, long way since their times.

- Yes it is quite conceivable that the sound I and many others enjoy could be because of 2nd harmonic distortion. I also suppose many people who like tube equipment will fall into that category as well, certainly I really like my Pass Korg B1 Preamp.

Cheers & thanks for the useful input.
 
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Let's not forget that Lofgren and Baerwald weren't too concerned with skating; that was a separate matter entirely beyond the question of lowest angular error. But now that we've gone beyond using steel needles with no vertical compliance I think it's fair to question the effect of unbalanced side forces on the highly compliant systems that we're all familiar with today.
 
Can someone explain what an under-hang tonearm is?

are you talking about how the cartridge is mounted? or how the arm mechanism connects to the TT base?

or??

I searched & didn't get any hits
 
bolero said:
Can someone explain what an under-hang tonearm is?

are you talking about how the cartridge is mounted? or how the arm mechanism connects to the TT base?

or??

I searched & didn't get any hits
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An underhung arm is shorter. KAB has a bit of a bias against the design, but explain, "We're discussing Scratch DJ straight pivoted underhung tonearms, not linear tracking straight tonearms nor straight tonearms with proper overhang and the offset angle in the headshell. . . You can tell the two different straight arm types apart very easily by seeing where the stylus lands relative to the spindle. Just bring the arm over to the spindle. In a high fidelity arm, the needle will "overhang" the spindle by 1/2" or so. In a scratch DJ arm, the needle will "underhang" or come up short about 3/8" behind the spindle. Also the high fidelity arm will have an angled headshell. The Scratch DJ arm will not."
 
If you want to see a audiophile under hang arm

Then look at

Viv Labs.

Review by Fremer at Stereophile mag here


Also the current Yamaha 5000 T/T has a 9'' U/H arm, T/T package has many outstanding reviews.

Cheers
 
jrtrent said:
In a scratch DJ arm, the needle will "underhang" or come up short about 3/8" behind the spindle. Also the high fidelity arm will have an angled headshell. The Scratch DJ arm will not
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Never mind the 1812 cannons, scratching has to be audio's toughest challenge. A million DJs the world over can't be wrong lol.
 
tabarddn51 said:
If you want to see a audiophile under hang arm

Then look at

Viv Labs.

Review by Fremer at Stereophile mag here


Also the current Yamaha 5000 T/T has a 9'' U/H arm, T/T package has many outstanding reviews.

Cheers
Click to expand...
That Stereophile review seems written to inform rather than just sell product. It's a shame that over time they drifted away from doing that.

But anyway, it brings us back to the title of this thread, "Math to show WHY under-hang tonearms sound superiors."

The math doesn't show that. It shows that even crude anti-skate correction applied to common TT geometry outperforms underhang geometry in the area where underhang is being claimed to be mathematically superior.
 
Hi, No U/H is not claiming to be superior to anti-skating correction, U/H is superior to arms set up with off-set angles tonearms in there various configurations. If the arm includes A/S, then that is purely the choice of the manufacturer, not all off-set arms do.
In my initial listening tests 2 years ago, I used a 12.5'' arm set to Lof B (no A/S was used & never has been with this arm) & compared it to the same arm set to U/H alignment, the improvement with U/H was not subtle.
Anti shaking is just a crude way of overcoming the short comings of the off-set angle alignment configurations.

This is from the What's Best Audio forum

Peter Ledermann and Michael Fremer, two exceedingly intelligent, insightful and well respected people with a wealth of experience, argue forcefully that skating force is real and requires a counter force to extract the last measure from our records. Harry Weisfeld, a man who dedicated his adult life to design of extraordinarily good turntables and tonearms is firm in his opinion that mechanical anti-skating methods only introduce another, and therefore unacceptable, potential for poor alignment. Interestingly, Peter Ledermann has commented that he has often seen the wear/damage to diamond stylus from the application of too much anti-skate force from hundreds of hours of record playing, yet insists that skating force is real and bad.

Cheers
 
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theophile said:
"The offset arm tends to pull towards the center of the disc"

You are aware that the spiral groove cut by the cutting head begins at the run-in groove and progressively moves incrementally in the direction of the spindle? Which direction did you think an offset arm would travel in that case?

Think about what you are reading. It helps.
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It wouldn't matter if the groove had been cut starting at the center and moved to the outside, the skating force would still be pushing the offset cartridge towards the centre of the record.
 
audiotemp said:
The math doesn't show that. It shows that even crude anti-skate correction applied to common TT geometry outperforms underhang geometry in the area where underhang is being claimed to be mathematically superior.
Click to expand...

This assumes that superior mathematical equations and measurements results in better sound. But this is often not the case. My own experiments with long "non-offset" underhung tonearms has further convinced me of this.
 
SoundMann said:
This assumes that superior mathematical equations and measurements results in better sound. But this is often not the case. My own experiments with long "non-offset" underhung tonearms has further convinced me of this.
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It is OP who introduced "math" here.
 
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Confession: I skipped the math (or purported math) section.
What I don't understand about underhung arms is how an arm that pivots, and whose stylus consequently traverses an ark, can escape skating forces. That arc means that, except at two points where the arc and a radius intersect, the stylus is being pulled sideways as well as forward. In an offset arm, the pull is always inward, but in an underhung arm, it is first in one direction than another. And this seems to me true whether the cartridge is held rigidly or allowed to pivot at the headshell/arm transition as some arms do.
So while I'm willing to think that at some points on a record the underhung arm might have less distortion, at others it will be worse. So I view this as a variant of the arguments about Baerwald/Lofgren/Stevenson/Angels dancing on the head of a pin*.
I will say that I am unconvinced by any implementation of antiskating I've seen since the skating force is pulling on the stylus but the antiskating mechanism is operating on the arm, so there is a torque applied to the cantilever which has to have an effect on alignment and relationship to the coils or magnets. I have been thinking attaching a thread or filament to the cantilever and apply a force to the thread. It seems very likely that the thread will resonate and probably sag and drag, and obviously it is a ridiculous idea, but it may be worth doing anyway.

* I misspelled angels and had angles, but this was kind of appropriate, anyway.
 
Nat said:
I will say that I am unconvinced by any implementation of antiskating I've seen since the skating force is pulling on the stylus but the antiskating mechanism is operating on the arm, so there is a torque applied to the cantilever which has to have an effect on alignment and relationship to the coils or magnets.
Click to expand...
That's only one problem, another is that we assume antiskating is a pure force, when in fact it's a mechanical force, and more often than not a badly implemented one.

The worst offender is the monofilament hanging over a hook as it will blurr transient dynamics, obscuring details as the filament saws back and forth over the hook with a relatively high friction component. Much better is a 2 pulley system with a weight, either hanging or cantilevered. Neither follows the skating gradient accurately but at least friction in the mechanism is reduced. The hanging weight in a 2 pulley system will have a constant gravitational pull that can be varied to track the skating gradient more precisely by using a secondary weight, but the additional weight increases inertia which negatively impacts the system's response to changes in direction. A spring is nearly massless but the force increases towards the center, opposite of what we want. That leaves magnetic AS, which is tricky to implement accurately and is more expensive so it is rarely found on affordable arms. Whichever one is used, none are adaptable on the fly to changes in the friction coefficient owing to vinyl formulation, music dynamics and stylus profile; you can optimize for one or two variables but not all three.

The easiest solution is to scrap the idea of AS altogether, but with an offset arm the stylus will wear on one side prematurely. With an underhung arm the forces are a better balanced which helps to even out stylus wear at the expense of marginally higher angular distortion. Is the tradeoff worth it? Those who've heard it mostly think so. Those who haven't will never know.
 
Hi, You guy's are totally correct, that U/H have more distortion at the outer & inner parts of the LP. However over on Lenco Heaven a group of us have worked together & have concluded that setting a Nul piont at 80mm from the LP center is the best compromise.
As you know with LP playing everything is a compromise. So at this point (80mm) the arm is acting as a parallel tracker for a very short period of play. But we have discovered tracking distortion is not discernable to the ears at any point across the LP's. So although the figures look large, especially with the 8.25'' arm I now prefer, it just cannot be heard during playback.
The improved S/Q noted now by many users (not everyone, but say 95% confirm an improvement) is now well established. It is not because the A/S is not needed, because for years I used & sold 12.5'' arms with no A/S, but when I moved to U/H I (and others) immediately heard a significant increase in S/Q & this is obviously what Fremer heard, from his description, as well
But yes, you have to hear it to believe it, which sadly means most will never know, but I am glad that we have finally got some descent discussion on the subject.

Cheers
 
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