2. analog
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is it time to mention tonearm's length again?

Hi folks,
I looked over quite a few posts related to the subject, tons of intricacies again which is great!
But one thing slipped my understanding, sorry, I am a little slow last ten years.
What I can not figure is - why longer arm helps traction (between the tip and the record). Or more to the point - I would think that the traction will be minimal when the tip's axis (provided such exists) is perpendicular to the line going from the tip to the spindle. I probably should know more about how the tip is built - in other words whether it does matter or not how the cartridge (and the tip) is positioned. But I thought the groove should go "along the cartridge". Now if as in my case the distance between the center of the arm base and the center of the disk is 9 inch and the tonearm is 12 inch long then the angle between the tonearm line and the line going to the center of the record becomes less then 90 degrees.
In the above example then with 12 inch arm - does it make sense to rotate the cartridge clockwise a little on the tonearm to get that angle back to 90 degrees? If above makes sense at all.
Sorry for the lengthy email. And thanks for your time.

Anatoliy
avs9
lewm
13,235 posts
 
When you say "traction", do you mean "tracking" (the ability of the cartridge to stay in the groove during difficult musical moments) or "friction" (force generated by stylus tip traveling in the groove that is counter to the rotation of the platter)?

Meantime, what the other guys say is correct. Mounting position (tonearm pivot to spindle) is much greater for a 12-inch arm than for a 10.5- or 9-incher. Each designer specifies how to mount his tonearm, usually, and usually provides some sort of template to assist you in correct mounting of tonearm and cartridge. In general a longer tonearm will produce less skating force, because the angle of the headshell with respect to a line drawn from the stylus tip through the tonearm pivot center gets smaller as effective length gets bigger. Skating force is also a function of the friction generated by the stylus tip, so I would think that longer tonearms produce also less frictional force. (Have to think about that a bit.)
bifwynne
2,206 posts
 
Lew, everything makes a lot of sense. Btw, I thought I read somewhere that the 12" arm, at one time, presented some stability and resonance design issues. I assume whatever may have been an issue a while ago has been worked out by now. Any thoughts on that point?
dougdeacon
3,338 posts
 
I thought I read somewhere that the 12" arm, at one time, presented some stability and resonance design issues.
All other things being equal, a longer arm will be less stable (internally) than a shorter one. When flexed, it will also resonate at a proportionally lower frequency. These things will affect the sound.

Of course all other things are not necessarily, or even very often, equal...
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