No it dosent. It is a pivoting arm with a long arm wand. And I also have a little nagging doubt about the way it tracks the record. It dosent follow a radius line , rather it follows a moving radius, and that will produce a speed error. If this moving radius moves a a constant speed, you can just adjust the speed of the platter, but I am not sure it is constant.
I agree with alighiszem. The Straight Tracker tonearm does what you proposed. Check out the video at the 12:20 mark.
It doesn't matter if the linear rail is short or not. If the linear bearing is inefficient, the stylus will be subject to deflection caused by the inefficient linear bearing even the rail is short. I am not sure how efficient the small linear bearing on Ralf's arm is. If the linear bearing is efficient, I would say why don't just make a linear arm.
As I see it, a long rail must have more imperfections than a very short one. I know from experience that it is difficult to make a 100mm long rail that is perfectly straight and with no imperfections, but a 5 mm -- that is another story. And then there is the weight ....
I have indeed seen this video and studied it very closely and as I have stated earlier, I am full of admiration of the servo system and the "floating Headshell" in Straight Trackers tonearm. I still feel it is unnecessary to put up with the long wand that has to have an impact on the vertical movement and the complicity of the geometry in such an arrangement and again the fact, that it does not follow a radius line .. I really don't know if a genuine straight tracking servo arm will perform better than Straight Trackers , but to me it seams easier to construct a genuine straight tracking servo arm as I have described.
Could magnetic levitation be utilized in a design such as this. If I understand, the deflection of the cantilever actually provides the motor to move the total arm.....??? Not sure how this could be a good thing if this is how it works. If I'm wrong, what is the impetus for the arm to move? Thanks in advance.
The Revox system IMO is not ideal. It is effectively a very short unipivot on a moving carriage. The very short, lets call it an arm wand causes high tracking error as the carriage catches up. The other issue with the Revox is minimal path for the energy imparted into the arm to be attenuated. I spent a LOT of time and effort to build a servo driven linear tracker and shelved the project due to the unacceptable level of noise the rail introduces. I still have my thinking cap on to solve this issue.
There are a couple of things that a tonearm MUST do to be good
1 Minimal noise in the moving parts, ie bearings and in the case of a LTA the carriage/rail.
2 Vibration energy must be dealt with and grounding this energy to the plinth is the best way. This rules out maglev.
Then there are more that make a TA outstanding
1 Rigidity
2 Very low static friction while maintaining rigidity
3 Energy again, this time dealt with in the armwand/CW stub/CW as well as grounding.
4 Mass distribution. Mostly overlooked by tonearm designers.
5 Minimal joints. Every joint reflects energy and is made worse by differing materials. A moving HS puts the mass and non rigid joint where you DO NOT want it.
My DIY pivoting TA has a variable taper and wall thickness. The CW stub is profiled so the reflected energy hits the arm wand interface at the critical angle reducing reflected energy back into the wand.
The HS is removable and uses a split collet arrangement and is made from the same aluminium as the wand to ensure a rigid joint and maximum energy transfer into the wand. There is a Lead disk between the brass CW stub and wand and a Lead CW rigidly attached to the stub. All these were designed to manage energy and reduce to a minimum energy reflected back to the cartridge.
A similar pivoting TA will be used on the linear rail once I solve the noise issue.
There are a couple of things that a tonearm MUST do to be good
1 Minimal noise in the moving parts, ie bearings and in the case of a LTA the carriage/rail.
2 Vibration energy must be dealt with and grounding this energy to the plinth is the best way. This rules out maglev.
Then there are more that make a TA outstanding
1 Rigidity
2 Very low static friction while maintaining rigidity
3 Energy again, this time dealt with in the armwand/CW stub/CW as well as grounding.
4 Mass distribution. Mostly overlooked by tonearm designers.
5 Minimal joints. Every joint reflects energy and is made worse by differing materials. A moving HS puts the mass and non rigid joint where you DO NOT want it.
My DIY pivoting TA has a variable taper and wall thickness. The CW stub is profiled so the reflected energy hits the arm wand interface at the critical angle reducing reflected energy back into the wand.
The HS is removable and uses a split collet arrangement and is made from the same aluminium as the wand to ensure a rigid joint and maximum energy transfer into the wand. There is a Lead disk between the brass CW stub and wand and a Lead CW rigidly attached to the stub. All these were designed to manage energy and reduce to a minimum energy reflected back to the cartridge.
A similar pivoting TA will be used on the linear rail once I solve the noise issue.
You are right Warren in saying the Revox is not the road to go , but that is because of the very flimsy armwand and bearing system. But as I said I would NOT use a unipivot but a small linear tracker and an arm with a pinpivot ONLY for the vertical movement. The arm wand should of course be made rigid and the pivot bearing as well. And the servo rail must be much more rigid than the Revox. I agree on all your points listed, but I feel this can be met, even if you make it like I suggest. The short arm wand has the advantage of being stiff light weight and not picking up much vibration because of its small physical dimension. You know this from your work on the passive linear tracker you made (and the Niffy arm) . I was thinking of and armwand like this or the one you suggested in your servo thread. The short length has no negative effect on the tracking as long as it is not a pivoting arm . This has been shown by Carlos and Niffy.
Here, for those interested (Mike?), the photo of the two carts of the CorkScrew mk2.
As you can not see, the differences A vs B cart are minimal for us humans but not for the cantilever behavior, fortunately.
From outside this CorkScrew mk2 is practically identical to mk1, so I refer you to # 4219 for the photo.
thanks - carlo
As you can not see, the differences A vs B cart are minimal for us humans but not for the cantilever behavior, fortunately.
From outside this CorkScrew mk2 is practically identical to mk1, so I refer you to # 4219 for the photo.
thanks - carlo
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Carlo, this is super work, looks so neat and tidy and i know functions well too, pretty much all one could wish for?
M
Hi koldby,
The styli of all tone arms travel either on a straight or a curved path. Whichever it is, is completely irrelevant. The only important requirement is that, the cantilever center line makes an angle of 90 degrees with a radius of random length between the start and the end of the modulated groove. Back in the 1980s, when I designed my first pivoting tangentially tracking tone arm, I realized that any pivoting tone arm's stylus moves "around" the LP's center by ~ 16 degrees clockwise depending upon the basic geometry of the tone arm, thus adding to the length of time it takes to play a particular piece of music. So I did the math and found this added length of time to be ~ 6 milliseconds! Next, I looked up what the accuracy of a quality metronome was and it didn't come anywhere near 6 milliseconds! If Doc Watson or the Berlin Philharmonic Orchestra played the same piece of music twice in a row, they would not be able to do that within 6 milliseconds.
I am sure others before me have discovered the above.Sincerely,
Ralf
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Hi koldby,
I prefer pivoting tangentially tracking tone arms for two reasons: 1) They look more handsome in my opinion, sitting there in one corner of a turn table and 2) They challenge a designer to get it right. Also in my opinion, the straight line tone arms like the Rabco etc overwhelm the average turn table. Some of them look like an HO model railroad car sitting on the side of the turn table. (Nothing personal Ray K) sic.
Sincerely,
Ralf
Hi koldby,
I have to admit that, when I first designed the floating head-shell in 2010, I did not fully understand why it would work! I just felt intuitively that it would! Because of that uncertainty, I mistakenly presented it as a servo controlled tangentially tracking tone arm. Once the tone arm worked and played music, I leaned back to think about what to do next when I realized that my tone arm wasn't a servo driven tone arm at all! Anyone who has looked at my tone arm will have noticed that it has an offset head-shell. The reason for the offset is not to reduce tracking error but to make the tone arm "self propelled" as it moves across the LP. In other words, I used what is normally called the skating force to propel the tone arm across the LP. The servo part of my tone arm really controls the amount of skating allowed to propel the tone arm across the LP. I do that with a Hall effect sensor that measures the centrality of the head-shell with respect to the cradle which in turn tells an op-amp circuit to adjust the degree of anti-skating.
The other reason for the offset head-shell is that, it reduces the distance that the tone arm's pivot has to be moved by ~50%! The length of the track upon which my 1980s tone arm moved was 1.650". The distance the pivot of my present tone arm moves is ~.870"!
You can't do the above with a tone arm that has a rigidly attached head-shell which brings me to this: All tone arms that achieve tangential tracking through the use of linkages like the Reeds cannot have a rigidly attached head-shell because the constrained path of the tone arm does not always agree with the location of the rotating spiral groove. Hopefully I will have enough time this weekend to draw some graphics to illustrate my point. If I can figure out how to draw a spiral in Autocad that is.
Sincerely,
Ralf
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Hi Gents, reflecting on the speed errors of a pivoting arm on its arc, i feel the desription assumes zero eccentricity, as there will always be some eccentricity, the arm will be going in and out the eccentricity difference each revolution, so that will multiply the earlier calculation of variation by 2 for the go and return and by the number of grooves for the entire record. thinking only about each revolution, and indeed the perhaps small part where there is eccentricity, is the speed variation discernible as a variation in pitch? if people with absolute pitch can discern 0.1% variation, does this suggest a problem or not?
M
I concur. The timing error is insignificant, even though it is there in any tonearm that is not pure tangential arm.Hi koldby,
The styli of all tone arms travel either on a straight or a curved path. Whichever it is, is completely irrelevant. The only important requirement is that, the cantilever center line makes an angle of 90 degrees with a radius of random length between the start and the end of the modulated groove. Back in the 1980s, when I designed my first pivoting tangentially tracking tone arm, I realized that any pivoting tone arm's stylus moves "around" the LP's center by ~ 16 degrees clockwise depending upon the basic geometry of the tone arm, thus adding to the length of time it takes to play a particular piece of music. So I did the math and found this added length of time to be ~ 6 milliseconds! Next, I looked up what the accuracy of a quality metronome was and it didn't come anywhere near 6 milliseconds! If Doc Watson or the Berlin Philharmonic Orchestra played the same piece of music twice in a row, they would not be able to do that within 6 milliseconds.
Sincerely,
Ralf
Hi Ralph.
Oh but this makes a lot of sense to me that it is more aesthetics and a drift towards make something that others haven't and will be hard pressed to do. I admire you work and the beauty of your arm and I , for one , could never make something this complicated mechanical or this beautiful
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I was wandering if this was the case . And you can only take advantage of the stylus drag... (that is actually what it is, skating is a result of this force . Much like centrifugal force is not a force, inertia is) if the headshell is allowed to move along with the groove. Very clever. A floating headshell in a strictly tangential arm, can only be moved by the side force on the cantilever.
I am now wondering if it would be possible to take advantage of the SD directly in the headshell hmmm...
If your tonearm is a servo driven tonearm or not is a matter of definition. If a servo driven tonearm is a tonearm where a servo system is necessary to either correct angle error or a position yours is AFAIK. Yours is not an ERROR CORRECTING servo and that is what I like about it and why I am investigating to make a stricktly tangential tracker, servo assisted, but not error correcting