Now that that is cleared up nicely.
Is it safe to assume then as the forces do not rely on the drag force in the groove (in the string pull test), that skate force is a result of the geometry only and drag force only contributes to the magnitude of the skate force?
Is it safe to assume then as the forces do not rely on the drag force in the groove (in the string pull test), that skate force is a result of the geometry only and drag force only contributes to the magnitude of the skate force?
On the contrary. The geometry determines the proportion of the drag force transformed to skating force. Geometry in itself does not produce skating force.
OK, but I didn't say geometry produced the skating force, the drag force creates it BECAUSE of the geometry?
I tried it on my Technics turntable tonearm. So easy to understand forces. I like simple clever things. Thanks for sharing. 🙂
Besides the pivot+offset producing some force I presume the concentric grooves walls also should be exerting some force. The inner groove walls being small in diameter should exert some more pressure too. Am I thinking right ?
Regards
Thank you for your vote of confidence. The string test demonstrates the concept of skating in a very simple way that anyone can see and understand, and it can be performed on any manually operated tonearm. It proves the point without requiring mathematical calculations or endless theoretical debates.
At inner grooves of 2.375 inches, and assuming a stylus major contact radius of 0.7 mil, the difference in radius between the left groove wall and right groove wall is under 0.03%. I'd rather not speculate on what effect that would have, other than to turn up the temperature on the antiskate setting debates. 😉
Ray K
Cold
Hi everyone,
Right after my last post concerning the skating force, I got taken down by a bad cold. I am OK now and am pleased that others have resolved the skating issue.
Sincerely,
Ralf
Hi everyone,
Right after my last post concerning the skating force, I got taken down by a bad cold. I am OK now and am pleased that others have resolved the skating issue.
Sincerely,
Ralf
OK understood. Lets ignore concentric walls.
Suppose there is zero friction linear tonearm. It is difficult to understand forces acting on tonearm assembly with respect to friction of groove walls and tonearm mass. 😕
Any idea ? I suppose we need wall friction and mass to keep stylus in the groove. What effects it has on movement of tonearm ? Will it need biasing ?
Regards.
Suppose there is zero friction linear tonearm. It is difficult to understand forces acting on tonearm assembly with respect to friction of groove walls and tonearm mass. 😕
Any idea ? I suppose we need wall friction and mass to keep stylus in the groove. What effects it has on movement of tonearm ? Will it need biasing ? Regards.
Say Ray,
Thanks for reminding of this simple test. I will use it to set up my Schroder LT clone for the various wands I have in mind. Seems much easier than doing the blank album thing.
Thanks for reminding of this simple test. I will use it to set up my Schroder LT clone for the various wands I have in mind. Seems much easier than doing the blank album thing.
Zero Friction Linear
Can you clarify your question please? I am not sure if the following answers your intent.
The averaged drag of the record's groove friction acts through the tonearm's 'pivot point' and creates no unbalanced force -- if we reasonably assume that the faster-moving outer groove creates an insignificantly different drag from the inner groove.
The lateral force on the stylus required to move the tonearm across the surface of the record is very insignificantly small, even in real-life examples with some friction in the linear track -- and in the case of your assumed zero friction, theoretically is a zero force.
The biggest causes of movement of the tonearm in your example are flaws in the record's shape, i.e. eccentricity of the hole, and vertical warps.
The former creates lateral forces on the stylus that are significantly smaller than the uncorrectable* component of the lateral skating forces on a pivoting tonearm. [*even assuming perfect correction of the static skating force with some antiskating mechanism, which is itself unlikely to occur, there remains the dynamic component which is uncorrectable]
The latter creates vertical forces exactly the same as for a pivoting tonearm.
Can you clarify your question please? I am not sure if the following answers your intent.
The averaged drag of the record's groove friction acts through the tonearm's 'pivot point' and creates no unbalanced force -- if we reasonably assume that the faster-moving outer groove creates an insignificantly different drag from the inner groove.
The lateral force on the stylus required to move the tonearm across the surface of the record is very insignificantly small, even in real-life examples with some friction in the linear track -- and in the case of your assumed zero friction, theoretically is a zero force.
The biggest causes of movement of the tonearm in your example are flaws in the record's shape, i.e. eccentricity of the hole, and vertical warps.
The former creates lateral forces on the stylus that are significantly smaller than the uncorrectable* component of the lateral skating forces on a pivoting tonearm. [*even assuming perfect correction of the static skating force with some antiskating mechanism, which is itself unlikely to occur, there remains the dynamic component which is uncorrectable]
The latter creates vertical forces exactly the same as for a pivoting tonearm.
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Thanks for explaining tnargs. The forces required to move tonearm in lateral tonearm arm design is negligible is exactly what I wanted to know.(Specially for air bearing) It was also said in air bearing tonearm in other thread too. So I presume air bearing lateral tonearm advantages are significant compared to pivoted tonearm with respect to bias and tracking both walls exactly as it was cut. I had a Technics SL-5 and it did sound good.
Regards.
Regards.
I'm not sure if this was posted before - Schallplattenspieler PS 2 from Ballfinger of Germany:
German brand unveils stunning new reel-to-reel tape machine & turntable
Schallplattenspieler PS 2 - BALLFINGER | Roland Schneider Feinwerktechnik
German brand unveils stunning new reel-to-reel tape machine & turntable
Schallplattenspieler PS 2 - BALLFINGER | Roland Schneider Feinwerktechnik
Reed 5T tonearm in action
This arm does not belong in the passive tangential arm discussed in the thread but it's still fun to look at! The motorized servo arm debuted at the recent 2017 Munich audio show. It's based on quasi-Birch geometry. Obviously expensive. I just wish the base is not so bulky that would allow for easier mounting. Certainly not designed for, say, a Linn LP12!
One thing I don't get in the high end audio is the lack of a finger lift. One of the ritualistic pleasures of vinyl is to be able to finger lift the arm to the desired part of the grooves. I understand the extra part might create resonance and mass imbalance but still...
Perfectionist audio is becoming more and more masochistic...
YouTube Video #1
YouTube Video #2
This arm does not belong in the passive tangential arm discussed in the thread but it's still fun to look at! The motorized servo arm debuted at the recent 2017 Munich audio show. It's based on quasi-Birch geometry. Obviously expensive. I just wish the base is not so bulky that would allow for easier mounting. Certainly not designed for, say, a Linn LP12!
One thing I don't get in the high end audio is the lack of a finger lift. One of the ritualistic pleasures of vinyl is to be able to finger lift the arm to the desired part of the grooves. I understand the extra part might create resonance and mass imbalance but still...
Perfectionist audio is becoming more and more masochistic... YouTube Video #1
YouTube Video #2
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Reed 5T WOW!
Watch Video #1 closely. Notice that, as the eccentric groove radius swings outward from the spindle, the arm tangency correction trajectory pulls the arm backward. As the groove radius swings outward from the spindle, the relative groove velocity increases from the eccentricity. As the servo attempts to maintain tangency on this outward groove radius swing, the arm and cartridge are concurrently being pulled backwards and the relative groove velocity increases from movement along the tangency correction trajectory. The reverse effect happens as the eccentric groove radius swings inward toward the spindle. These two negative effects sum together, and we should expect this type of servo action to further compromise wow performance on eccentric discs.
Thoughts?
Ray K
Watch Video #1 closely. Notice that, as the eccentric groove radius swings outward from the spindle, the arm tangency correction trajectory pulls the arm backward. As the groove radius swings outward from the spindle, the relative groove velocity increases from the eccentricity. As the servo attempts to maintain tangency on this outward groove radius swing, the arm and cartridge are concurrently being pulled backwards and the relative groove velocity increases from movement along the tangency correction trajectory. The reverse effect happens as the eccentric groove radius swings inward toward the spindle. These two negative effects sum together, and we should expect this type of servo action to further compromise wow performance on eccentric discs.
Thoughts?
Ray K