Koldby,
Using DVD drive is a clever idea. However, it may add complexity of arm. Motor noise may be another problem. In any cases, I will love to see if you can come up something.
For tonearm wire, I don’t think there is any problem at all if you use magnet wires. I used wire from a pair of head phone wires. The wire I used is about 40G. I think it produces very little or no drag and down force.
Air tubing is a problem. It seems to me that Kuzma uses 1/16” pvc tubing. A pvc tubing like Kuzma’s will produce horizontal drag and vertical down force. Let’s assume there is a mechanism to move the tubing according to the position of air bearing. But it only solves the horizontal drag. The vertical down force generated by tubing still exists.
The solution I found here may be the best possible I can have. If you look back this thread, I used 1/32” tubing. I had done many experiments and am pretty sure that the tubing I am using has very little horizontal drag and almost no vertical down force. The beauty of this tubing is it can take high air pressure up to 80 PSI.
The ID of tubing is small. It will limit the flow. This is a good thing too. For air bearing, it needs high pressure and low flow.
Jim
Using DVD drive is a clever idea. However, it may add complexity of arm. Motor noise may be another problem. In any cases, I will love to see if you can come up something.
For tonearm wire, I don’t think there is any problem at all if you use magnet wires. I used wire from a pair of head phone wires. The wire I used is about 40G. I think it produces very little or no drag and down force.
Air tubing is a problem. It seems to me that Kuzma uses 1/16” pvc tubing. A pvc tubing like Kuzma’s will produce horizontal drag and vertical down force. Let’s assume there is a mechanism to move the tubing according to the position of air bearing. But it only solves the horizontal drag. The vertical down force generated by tubing still exists.
The solution I found here may be the best possible I can have. If you look back this thread, I used 1/32” tubing. I had done many experiments and am pretty sure that the tubing I am using has very little horizontal drag and almost no vertical down force. The beauty of this tubing is it can take high air pressure up to 80 PSI.
The ID of tubing is small. It will limit the flow. This is a good thing too. For air bearing, it needs high pressure and low flow.
Jim
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For the wire and tubing I am using, I don't see the need for that. Using a hook may make things worse in stead of solving the problem.
Jim
This kinds of air bearing arm does exist. But it can't work with high air pressure. Higher air pressure means stiffer bearing.
Jim
Hi guys,
IMO the addition of a servo to an air bearing arm is completely unnecessary. The aim is to reduce the lateral tracking error. Lateral tracking error can arise from several sources.
Bearing friction and wires/air hose. Bearing friction with an air bearing is effectively zero. The drag due to air hose and wires is also very low. I made many different arm wires to test their effects. I increased wire thickness until no further sound improvements were heard. (4 strands of 0.06mm enamel wire per channel) This wire is stiff enough to support its own weight but so flexible that it was below the resolution of my bearing friction testing rig. Side force to move wires probably less than 0.01g.
I haven't personally tested air hose but check out Jim's video of his neutrally balanced arm sliding back and forth. The air hose appears to have virtually no effect. (The slight resistance of the air hose may actually be beneficial. The original Kuzma airline didn't have a damping trough but relied on the air hose to damp the arm. Only after a reviewer knocked the arm for not having a damping trough did Frank add one (even though the reviewer stated that it was the best arm he had heard) Many users don't use the trough.)
On a perfectly centred record lateral tracking error is to all intent and purpose zero with an air bearing arm. With an eccentric record you have the mass inertia effect (often called the tail wagging the dog) This causes a small amount of lateral tracking error. Even with a heavy arm like Jim's and a severe eccentricity the amount of error is very small.
The tracking error due to the groove angle caused by the eccentricity is massively higher than the tracking error due to mass inertia, bearing friction and hose drag.
With an air bearing arm playing an average record the lateral tracking error is probably less than your or my ability to align the cartridge in the first place.
Any improvements a servo could bring are probably going to be less than alignment error and DEFINITELY a lot less than groove angle due to eccentricity. In other words not audible.
The added complexity is more likely to be detrimental than beneficial. As I initially stated these are my opinions but they are based in solid reasoning.
Niffy
IMO the addition of a servo to an air bearing arm is completely unnecessary. The aim is to reduce the lateral tracking error. Lateral tracking error can arise from several sources.
Bearing friction and wires/air hose. Bearing friction with an air bearing is effectively zero. The drag due to air hose and wires is also very low. I made many different arm wires to test their effects. I increased wire thickness until no further sound improvements were heard. (4 strands of 0.06mm enamel wire per channel) This wire is stiff enough to support its own weight but so flexible that it was below the resolution of my bearing friction testing rig. Side force to move wires probably less than 0.01g.
I haven't personally tested air hose but check out Jim's video of his neutrally balanced arm sliding back and forth. The air hose appears to have virtually no effect. (The slight resistance of the air hose may actually be beneficial. The original Kuzma airline didn't have a damping trough but relied on the air hose to damp the arm. Only after a reviewer knocked the arm for not having a damping trough did Frank add one (even though the reviewer stated that it was the best arm he had heard) Many users don't use the trough.)
On a perfectly centred record lateral tracking error is to all intent and purpose zero with an air bearing arm. With an eccentric record you have the mass inertia effect (often called the tail wagging the dog) This causes a small amount of lateral tracking error. Even with a heavy arm like Jim's and a severe eccentricity the amount of error is very small.
The tracking error due to the groove angle caused by the eccentricity is massively higher than the tracking error due to mass inertia, bearing friction and hose drag.
With an air bearing arm playing an average record the lateral tracking error is probably less than your or my ability to align the cartridge in the first place.
Any improvements a servo could bring are probably going to be less than alignment error and DEFINITELY a lot less than groove angle due to eccentricity. In other words not audible.
The added complexity is more likely to be detrimental than beneficial. As I initially stated these are my opinions but they are based in solid reasoning.
Niffy
As I see it it can work with the same pressure as your arm. It is not a Forsell type of bearing I am talking about. No air holes outside the bearing in my idea, therefore the restricted movement.
Koldby,..
Where i say i don't like idea? I just said that it would be more complicated and expensive for diyers to achieve and furthermore if you please i would like to see any sort of drawing to understand better.
If your airbearing is connected to a carriage which slide on rollerbearing activated by stepper motor than it defeat its purpose and will introduce feedback resonances from stepper motor drive belt or screw no matter what u use.
So again i would like to see drawing to understand better
My tapered carbon wand will be less than 5inch long and with high taper ratio so it will be better than any tangent tone arm and as i said previously i dont like idea of whole package above my records.
Again my perception of do it yourself does not involve all to be done at home when i have resources to be built relatively inexpensive on CNC machines
So don't jump with conclusions my friend
Cheers
Zz
Please this is not a fight. I am merely presenting some ideas to the forum and I am not jumping to conclusions.
As I see it, only lateral imperfections from the roller bearing/ motor could be transmitted (if they exist) Horizontal movements are not transmittet as the air bearing is frictionless eg. cannot detect any movement of the sledge (or whatever is used).
Really, this is something new to me. Would you please let have the link so I can take a look?
Thanks!
Jim
Maybe it will complicate things too much, I am not that sure it will.
I have never liked the hanging/suspended wires and that I have to restrict myself to very flexible wires .I like solid core silver in teflon tubing soundwise and I cannot use them in LT arm.
Also I like the thought of an arm that is operated by electronics and not my old shaking hands. Maybe all that comes out of my thinking and trial and errors will be an automatic lift... Any objections to that
What link?
I have attached a very quick an dirty drawing of the inverse air bearing. The ring never comes outside the area with the holes in the shaft.
Attachments
Koldby,.. as you said, "could be transmitted" "if they exist", and they always exist in roller bearing and you need to be aware that if they exist, its always vertical component involved where air bearing isn't immune and that again mean that it defies its purpose plus any resonances transmitted from stepper motor via belt or screw to carriage ball bearing will be transmitted to airbearing trough its vertical componennt. It is not a fight my friend. Just logical reasoning
Cheers
Zz
This was rough calculus in between servicing my compound bow and refletching my new arrows
I will know more when i start to create 3D models and check volume analysis.But if i end up total even above 200grams i will be extremely happy fellow
Cheers
Zz
This was rough calculus in between servicing my compound bow and refletching my new arrows
But if i end up total even above 200grams i will be extremely happy fellow
Cheers
Zz
200 g is probably ok for certain cartridges. However, I won't advise to go over 200 g. 150 g may be the best for wider selections of cartridges.
Logical reasoning would also say that airborne vibrations (high volume playback) would be picked up by the long airtubes and maybe wires and the question is: is the cure for this worse than the illness. I don´t know, maybe you do, my friend?Koldby,.. as you said, "could be transmitted" "if they exist", and they always exist in roller bearing and you need to be aware that if they exist, its always vertical component involved where air bearing isn't immune and that again mean that it defies its purpose plus any resonances transmitted from stepper motor via belt or screw to carriage ball bearing will be transmitted to airbearing trough its vertical componennt. It is not a fight my friend. Just logical reasoning
Cheers
Zz
Koldby,..
Even if there are any, you would minimize or entirely remove the same, but introduce others which will put you on square one with more money invested and overly complicate such a beautiful design.
In order to prove your theory i advice you to build that and show us. I will be happy for you.
Since i was listening much of the Franc Kuzma tonearms lately , including Airline as well at moderately loud volumes i could say there are no such problems overly exaggerated as you imply , but than again i will wait for your design to be made and tested and will decide accordingly.
Maybe Jim and Niffy can say something about it. They have more experience on the subject. I am really tired and going to sleep.
Cheers
Zz over and out
Even if there are any, you would minimize or entirely remove the same, but introduce others which will put you on square one with more money invested and overly complicate such a beautiful design.
In order to prove your theory i advice you to build that and show us. I will be happy for you.
Since i was listening much of the Franc Kuzma tonearms lately , including Airline as well at moderately loud volumes i could say there are no such problems overly exaggerated as you imply , but than again i will wait for your design to be made and tested and will decide accordingly.
Maybe Jim and Niffy can say something about it. They have more experience on the subject. I am really tired and going to sleep.
Cheers
Zz over and out
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You are much more likely to pick up airborne feedback via the much greater surface area of the carriage body than via the air tube or wires. Also, as the carriage is much more rigid, vibrations picked up by the carriage body are more likely to be transmitted to the cartridge. If you think that airborne feedback is likely to be a problem do as I have and build a thick acrylic cover. I actually built mine to protect the deck from my cats but it should work to reduce sound pressure by several dB. In reality I can determine no real difference between lid on and lid off. I think, at least for my arm, that it is a non-problem, and my arm has big flat faces ideal for picking up feedback.
Niffy
Niffy