tabarddn51
Super Member
A couple of weeks ago I was asked to show the above math for the above. As I do not want to clog up the Under Hang thread with discussion's about this detail, I decided to post it on a separate thread.
''Designer Akimoto-san’s primary argument is this: the offset angle added by Baerwald to almost all tonearms today is fundamentally flawed in that it magnifies side-force variations to an unacceptable level. Let’s use some elementary vector force mathematics to look at this in a bit more detail.
Side force at any particular tonearm position is given by the formula
µW*tan(α+?), where
µ is the friction coefficient between the stylus and groove,
W is the stylus tracking force (or VTF)
α is the tracking error angle and
? is the offset angle
The ideal situation is where µW, representing the total friction force of the stylus, does not favour either wall of a groove. This would meana side force of 0; in other words, the formula tan (α+?) should give a null value. Any other value given by tan (α+?) will mean that some part of the total stylus friction force is vectored towards the wall of the groove closer to the label (or the left wall if you are looking at a stylus head-on).
Baerwald alignment advocates aligning a 25° (24.63° to be exact) offset tonearm to achieve 3 maxima and 2 minima, points where the lateral tracking error (LTE) is the highest and zero respectively. At the highest point of LTE, Baerwald calculations give a tracking angle error of 1.5° (whether the angle is positive or negative does not matter, LTED is the same).
At the point of minimum tracking error angle (α=0) the side force will be: tan (24.63) which is 0.45846925. At the maximum tracking error angle (α=1.5°) the side force is tan (24.63+1.5) which yields 0.49054437. This means that almost exactly half of the total stylus friction force is given over to pushing against the side wall without any anti-skating correction. Anti-skating is the brute use of force to cancel off the effect of a non-zero tan (α+?), which is neither elegant nor ideal. It’s like this: imagine a car in one of its gears (we don’t know which gear and that changes every second) and wants to move forward; to make it stay still, we have two choices; use a fixed force on a rope to pull it backwards, or shift the gearbox to neutral. The question “which is preferable?” is almost a no-brainer, the former having problems of wear, lagging response times, insufficient or over use of force, & c.
So a straight tonearm with no offset is like shifting the car to neutral gear. Even if we take a worst case scenario of a 10° tracking error angle, tan (10) will still only yield 0.18, which is way better than the best case in an offset arm.''
The full article can be found here
Cheers
''Designer Akimoto-san’s primary argument is this: the offset angle added by Baerwald to almost all tonearms today is fundamentally flawed in that it magnifies side-force variations to an unacceptable level. Let’s use some elementary vector force mathematics to look at this in a bit more detail.
Side force at any particular tonearm position is given by the formula
µW*tan(α+?), where
µ is the friction coefficient between the stylus and groove,
W is the stylus tracking force (or VTF)
α is the tracking error angle and
? is the offset angle
The ideal situation is where µW, representing the total friction force of the stylus, does not favour either wall of a groove. This would meana side force of 0; in other words, the formula tan (α+?) should give a null value. Any other value given by tan (α+?) will mean that some part of the total stylus friction force is vectored towards the wall of the groove closer to the label (or the left wall if you are looking at a stylus head-on).
Baerwald alignment advocates aligning a 25° (24.63° to be exact) offset tonearm to achieve 3 maxima and 2 minima, points where the lateral tracking error (LTE) is the highest and zero respectively. At the highest point of LTE, Baerwald calculations give a tracking angle error of 1.5° (whether the angle is positive or negative does not matter, LTED is the same).
At the point of minimum tracking error angle (α=0) the side force will be: tan (24.63) which is 0.45846925. At the maximum tracking error angle (α=1.5°) the side force is tan (24.63+1.5) which yields 0.49054437. This means that almost exactly half of the total stylus friction force is given over to pushing against the side wall without any anti-skating correction. Anti-skating is the brute use of force to cancel off the effect of a non-zero tan (α+?), which is neither elegant nor ideal. It’s like this: imagine a car in one of its gears (we don’t know which gear and that changes every second) and wants to move forward; to make it stay still, we have two choices; use a fixed force on a rope to pull it backwards, or shift the gearbox to neutral. The question “which is preferable?” is almost a no-brainer, the former having problems of wear, lagging response times, insufficient or over use of force, & c.
So a straight tonearm with no offset is like shifting the car to neutral gear. Even if we take a worst case scenario of a 10° tracking error angle, tan (10) will still only yield 0.18, which is way better than the best case in an offset arm.''
The full article can be found here
Cheers
