Hi Super.
In order for the arm to track from the outer groove on the right to the inner groove on the left the arm moves to the left. To move an object to the left a force must be applied from the right. This force is applied by the spiralling groove to the right hand side of the stylus by the right hand side of the groove. This means that the pressure on the right-hand side side of the stylus/groove is greater than on the left-hand side. If I'm not mistaken the test track is a 315hz recorded at a high level. The right-hand side of the stylus is pressed firmly to the groove and remains in contact hence no distortion. The left-hand side is pressed less firmly in to the groove and looses contact with the groove wall momentarily at the left hand peeks of the modulation. This is why the distortion occurs on the left-hand channel. There is of course the addition of an LTA error.
If the record has a large eccentricity the arm will be moved to the right as well as the left causing the distortion to switch from one channel to the other as the arm moves back and forth. The distortion would still be greater on the left as the predominant movement is still to the left.
If the eccentricity is very small, less than the pitch of the grooves spiral, the arm will step to the left, pause, then step left repeatedly. This case would also only show distortion in the left channel but the level of distortion would increase and decrease at the same rate as the record revolves.
I hope this makes sense.
Niffy
Stylus tracking is indeed a complex issue.
It could be argued for a perfectly centred disc and a frictionless sled (the aim of air bearing System ?) and zero mass sled, there should be equal stylus groove wall contact pressures/forces.
The real world is different of course.
For the condition of perfectly centred record and zero sled lateral resistance, sled mass should have no influence once the sled has commenced lateral motion, assuming constant groove pitch.
Any sled movement resistance will cause change in ratios of groove wall contact pressures, and lateral deflection of stylus/cantilever assy.
The stylus suspension (usually rubber) material has compliance, but also has viscosity/remnance....this causes delay in return of cantilever to central home position, and consequent dynamic inequality of groove contact pressures.
Sled/short arm/cartridge mass further complicates interactive dependencies.
The conventional arm translates forces to longitudinal forces on the cantilever which is a cantilever centering restorative force, albeit with a skating residual, which is commonly compensated by weight or spring force.
Wireless World magazine in the 70s/80s ? published a mathematical study on the LTA errors incurred by conventional straight and S-shaped arms...the conclusion was that no conventional arm can track perfectly across the whole record surface, but the errors of S-shaped arms can be less.
I have stated that passive linear tracking is flawed, and for the reasons I give above.
Add eccentric records, and variable groove pitch records, and the situation is worsened.
As I see it, the only proper solution is a servo driven sled, and done correctly should be measurably more correct than conventional or linear tracking passive techniques.
Dan.
Hi Dan.
Tracking sure is complex, finding the best system which does not compromise other aspects of the arm is tricky. For instance I think pivoted tangential trackers introduce to many other compromises and don't sound as good as a comparable conventional pivoted arm.
If the bearing was totally frictionless and the carriage massless, the effective mass would be also be zero, so the compliance/effective mass resonance would be infinite resulting in no sound. Mass is essential for the cartridge to work.
Servo control might be the best option but the correction mechanism would have to be very sensitive, sensitive enough correct the arms position before LTA error had built up to even a tiny fraction of a degree. The correction mechanism would also have to introduce no nasties of it own such as noise. The only servo controlled record players I have had experience of were from a Kenwood midi system and a bang and olufsen 9000 both of which were God awful.
No arm can ever be 100% perfect, so in that way passive linear tracking is flawed but less flawed than virtually any other system. I didn't choose linear tracking in an attempt to reduce tracking error rather because it enabled me to build an arm whose resonant frequency was above the audio bandwidth. This has had a massively bigger positive impact than any improvement in tracking ever could.
Niffy
Tracking sure is complex, finding the best system which does not compromise other aspects of the arm is tricky. For instance I think pivoted tangential trackers introduce to many other compromises and don't sound as good as a comparable conventional pivoted arm.
If the bearing was totally frictionless and the carriage massless, the effective mass would be also be zero, so the compliance/effective mass resonance would be infinite resulting in no sound. Mass is essential for the cartridge to work.
Servo control might be the best option but the correction mechanism would have to be very sensitive, sensitive enough correct the arms position before LTA error had built up to even a tiny fraction of a degree. The correction mechanism would also have to introduce no nasties of it own such as noise. The only servo controlled record players I have had experience of were from a Kenwood midi system and a bang and olufsen 9000 both of which were God awful.
No arm can ever be 100% perfect, so in that way passive linear tracking is flawed but less flawed than virtually any other system. I didn't choose linear tracking in an attempt to reduce tracking error rather because it enabled me to build an arm whose resonant frequency was above the audio bandwidth. This has had a massively bigger positive impact than any improvement in tracking ever could.
Niffy
Thinking about mass and resonant issues with a short arm in comparison to a longer one, realize that the split low frequency resonant modes of these designs, your vertical resonance will go up with the shorter version and it best to move the counterweight as far back as possible to counteract this tendency. The fluid damping should help also.
I agree with Niffty on the short arm as any arm tube resonance is pushed well out of any frequency that could add in the hearing range. There's simply no arm to speak of
Regards
David
I agree with Niffty on the short arm as any arm tube resonance is pushed well out of any frequency that could add in the hearing range. There's simply no arm to speak of
Regards
David
When you mention split low frequency resonance modes I assume you are referring to the lateral and vertical effective masses being different. The vertical effective mass will tend to decrease, pushing up the vertical resonant frequency, if the arm is shortened as the mass of a shorter arm tends to be lower. Pushing the counterweight further back will increase effective mass but in doing so will lower the rigidity of the arm bringing the arms resonant frequency lower into the audio bandwidth. My method was to increase arm mass. This increased effective mass whilst keeping the rear section of the arm short helping to keep arm resonant frequency high. Furthermore all the material used to increase the arms mass was used to also stiffen the carriage as much as possible enabling me to push the arms resonant frequency to nearly 20khz. Of course this pulls the lateral cantilever resonance down, just under 5hz. This is not a problem. In a conventional arm It is recommended for the cantilever resonance to be 9.5-10hz as significant warps occur up to about 6hz. 9.5hz is safely above this. Warps only effect vertical movement. Laterally the only driving force is due to record eccentricity which is at 0.55hz. So my 5hz is safely above this.
It is commonly thought that having wildly different effective masses also negatively effects the way the arm behaves at audio frequencies. This would probably be true. However a linear tracking arm only moves the whole arm sideways at very low frequencies. At audio frequencies the arm actually rotates about its centered of mass. The play in the bearing (air gap in an air bearing) is more than enough to permit this movement. The angle of rotation is incredibly small, less than an arcsecond, so does not effect tracking angle. So at audio frequencies the lateral effective mass is lowered to be similar to the vertical effective mass.
Niffy
I agree with you completely. My test shows it too. Speaking of eccentricity, all the records have certain degree of eccentricity. It is almost inevitable. So, the problem is degree of eccentricity. In 98% of cases, the level of eccentricity is so low that distortion still happens in left channel. In other words, eccentricity won’t have effect on the playing back of records. In my opinion, eccentricity should not be our concern at all. It is negligible. Eccentricity also won’t throw the stylus from left to right and from right to left. If eccentricity is so severe, the disk is not playable.
Back to Fremer’s Kuzma air line review, he is wrong. In normal condition, eccentricity won’t throw the stylus from side to side. Even if eccentricity is very severe, I am still doubt that the stylus will be thrown from side to side.
I plan to redo the carriage of bearing so the arm will be another 1/8" shorter. The new carriage will be made from a block of aluminum so the structure of carriage will be much rigid. I thought the same as you do. Please see the photo. I tried to move the counterweight far away from the bearing. The carbon fiber tube for counter weight is almost 2 times longer than the headshell. But I am doubt if it helps because it adds lateral mass as well.
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With more leverage at a distance you use less counterweight mass overall and probably gain a leverage advantage to keep peak amplitude resonance reduced.
Even if you used more CW mass on a shorter beam, and the total weight wound up being the same as the longer combo, I would still see the advantage of the leverage principal as a stablizing agent for the cartridge.
This would be predicated on the idea that the vinyl is flat by either vacuum or perimeter clamp like you have.
Vertical warps would favor the close CW to the pivot, but this short pivot design should be never be used with warped records on any TT.
Regards
David
Even if you used more CW mass on a shorter beam, and the total weight wound up being the same as the longer combo, I would still see the advantage of the leverage principal as a stablizing agent for the cartridge.
This would be predicated on the idea that the vinyl is flat by either vacuum or perimeter clamp like you have.
Vertical warps would favor the close CW to the pivot, but this short pivot design should be never be used with warped records on any TT.
Regards
David
Michael Fremer's review of the Kuzma air lines is one of the strangest reviews I have ever read. He demonstrates that he doesn't really understand the design principles behind the arm, then attacks the design based on common misconceptions/myths about linear tracking arms. Then states that it is the second best arm he had ever heard, better than a Graham 2.2 high praise indeed. He doesn't report any of his misgivings actually occurring. Then marks the arm down for not having a feature that his listening test had just proved it didn't need, his description of the low frequency performance showed that additional damping was not required.
File under:- What the ...?
Niffy
Hi Super.
I've never heard the ZYX airy. The UK distributer, Origin Live, was using an ortofon cadenza black at the last show I visited. Maybe they've only taken on this brand recently. I've just read a bunch of reviews and it sound like just my type of cartridge, accurate and neutral with no romanticizing of the music. The reviews use almost exactly the same words as were used to describe the ortofon mc3000mk2, which I used to own and was a truly excellent cartridge. That's a really serious bit of kit you have.
Jealous Niffy.
I've never heard the ZYX airy. The UK distributer, Origin Live, was using an ortofon cadenza black at the last show I visited. Maybe they've only taken on this brand recently. I've just read a bunch of reviews and it sound like just my type of cartridge, accurate and neutral with no romanticizing of the music. The reviews use almost exactly the same words as were used to describe the ortofon mc3000mk2, which I used to own and was a truly excellent cartridge. That's a really serious bit of kit you have.
Jealous Niffy.
Hi Niffy,
I mentioned zyx because it is a high compliance cartridge. It can't track correctly without damping. I am still thinking to add a silicone oil or eddy current damping device as a base for damping then to use my own damping device to balance the lateral force. Or, I may be thinking too much. ;-)
I mentioned zyx because it is a high compliance cartridge. It can't track correctly without damping. I am still thinking to add a silicone oil or eddy current damping device as a base for damping then to use my own damping device to balance the lateral force. Or, I may be thinking too much. ;-)
Hi Super.
The reviews I read all quote the zyx compliance as 15um/mN. This is pretty typical for high end moving coils and is normally said to be mid compliance. High compliance is normally reckoned to be 20-25um/mN. A silicon damping trough may be worth considering. Your current design will be good for damping very low frequencies but will be less effective at helping to reduce arm movement at audio frequencies. Silicon will damp over a much broader range of frequencies so it's effects may be beneficial.
Still jealous.
Niffy
The reviews I read all quote the zyx compliance as 15um/mN. This is pretty typical for high end moving coils and is normally said to be mid compliance. High compliance is normally reckoned to be 20-25um/mN. A silicon damping trough may be worth considering. Your current design will be good for damping very low frequencies but will be less effective at helping to reduce arm movement at audio frequencies. Silicon will damp over a much broader range of frequencies so it's effects may be beneficial.
Still jealous.
Niffy
The zyx compliance is 15xl0ˉ6. I said it is high compliance based on following article.
Tonearm/Cartridge Capability
“A phono cartridge whose compliance is rated at 12 x l0ˉ6 or below, is considered low compliance. A cartridge whose compliance is rated between 13 x l0ˉ6 and 25 x l0ˉ6 is considered high to very high. Note: Another way of expressing compliance is um/mN. Here a rating of 5 to 10 is considered very low, 10 to 20 is moderate and above 35 is very high.”
However, if you want to call 15x0ˉ6 medium compliance, it is fine with me because it is just a word. It doesn’t have significant implication for tonearm designs.
Anyway, silicone oil damping may eliminate small movements more effectively than my damping device. I may try to attache a piece of rubber band or tiny spring on the string of my damping device.
I also have a great idea for applying eddy current damping method. But for my arm, I need to make sure that the magnetic field will not affect cartridge.
Tonearm/Cartridge Capability
“A phono cartridge whose compliance is rated at 12 x l0ˉ6 or below, is considered low compliance. A cartridge whose compliance is rated between 13 x l0ˉ6 and 25 x l0ˉ6 is considered high to very high. Note: Another way of expressing compliance is um/mN. Here a rating of 5 to 10 is considered very low, 10 to 20 is moderate and above 35 is very high.”
However, if you want to call 15x0ˉ6 medium compliance, it is fine with me because it is just a word. It doesn’t have significant implication for tonearm designs.
Anyway, silicone oil damping may eliminate small movements more effectively than my damping device. I may try to attache a piece of rubber band or tiny spring on the string of my damping device.
I also have a great idea for applying eddy current damping method. But for my arm, I need to make sure that the magnetic field will not affect cartridge.
Compliance is useful, as described in the article linked in your previous post, in order to select correct effective mass.
However when you are using a linear tracking arm with records clamped flat the normal rules for determining correct effective mass no longer apply. In this case much higher effective masses can be used. The main mechanism that holds the cartridge still relative to the groove is mass and a higher mass holds the carriage more still... Better sound.
Niffy
However when you are using a linear tracking arm with records clamped flat the normal rules for determining correct effective mass no longer apply. In this case much higher effective masses can be used. The main mechanism that holds the cartridge still relative to the groove is mass and a higher mass holds the carriage more still... Better sound.
Niffy
Niff,
I know you are a fan of electrostatic speaker. I am also a panel speaker guy. I currently use Sound Lab Majestic 945. My 945 is not normal 945. I have been modifying the speaker up to now. Sound Lab speakers have the tendency to sound dark without right amplification but not my pair. Sound Lab speaker don’t sound filmy as other electrostatic speakers. Bass is excellent if the amplification is right. To improve my Majestic 945, I did following.
Bi-amping, Wolcott P400(high/mid), Spectron Musician III(bass)
Heavy duty sand filled steel frame.(Speaker frame fastened on back wall).
Ribbon super tweeters( 4 in front, 2 on the back, 2nd order crossover)
Speaker grill cloth off completely.
Internal crossover completely discarded.
Adding a pair of REL storm subs.
A pair of Martin Logan Aerius wired out of phase on rear corners to produce ambient sound.
Picture was taken a while ago. My room is little different now. It is a little messier and REL subs are in the front of 945 and fire up instead of firing down.
I know you are a fan of electrostatic speaker. I am also a panel speaker guy. I currently use Sound Lab Majestic 945. My 945 is not normal 945. I have been modifying the speaker up to now. Sound Lab speakers have the tendency to sound dark without right amplification but not my pair. Sound Lab speaker don’t sound filmy as other electrostatic speakers. Bass is excellent if the amplification is right. To improve my Majestic 945, I did following.
Bi-amping, Wolcott P400(high/mid), Spectron Musician III(bass)
Heavy duty sand filled steel frame.(Speaker frame fastened on back wall).
Ribbon super tweeters( 4 in front, 2 on the back, 2nd order crossover)
Speaker grill cloth off completely.
Internal crossover completely discarded.
Adding a pair of REL storm subs.
A pair of Martin Logan Aerius wired out of phase on rear corners to produce ambient sound.
Picture was taken a while ago. My room is little different now. It is a little messier and REL subs are in the front of 945 and fire up instead of firing down.
Ok. Even more jealous now.
I'm not familiar with your amps, but I know the sound labs are stunning (even unmodified). I'll have a web search for the amps. I spied a nice bit af room treatment going on too. Fabulous but I'd never get wife approval.
Time for an admission. In post 45 I missed the square button on my calculator. The cantilever deflection would have been 0.07Degrees not 0.02. Still negligible.
Niffy
I'm not familiar with your amps, but I know the sound labs are stunning (even unmodified). I'll have a web search for the amps. I spied a nice bit af room treatment going on too. Fabulous but I'd never get wife approval.
Time for an admission. In post 45 I missed the square button on my calculator. The cantilever deflection would have been 0.07Degrees not 0.02. Still negligible.
Niffy