You misunderstood the meaning of another pair of wheels located at the back.
I put them so that during the operational movement of the tonearm with my hand, the float does not touch the back of the foam plastic to the glass surface of the aquarium, otherwise the foam plastic slows down.
In the case of finding another pair of wheels, the tonearm can be quickly moved to the beginning of the plate without any problems.
Understand that a system with one pair of wheels, a pulling force of a groove and a triangle - two wheels + a head are self-sufficient, while the tonearm works flawlessly and this can be seen in the video.
We need to make another video clip so that you understand how it works.
I was thinking about avoiding yaw, as Jim (super10018) suspected, and came up with an idea and wonder if it would work... What if I use two thin horizontal round glass rods glued together submerged in water and have a carriage made of floating material with only two wheels rolling on the track between the two rods and a tonearm mounted the carriage between the two wheels, which takes care of the horizontal movement and the wheels' contact points creates a pivot that's for the vertical movement. That should be able to avoid yaw movement, no? The floating material can be adjusted to the desired amount of applied pressure on the track. Instead of a typical mechanical parallel tracking arm with all the mass of the arm rolling on the contact points, the floating material helps to lessen the mass but still having mechanical grounding. The water or fluid helps to dampen movements. I don't have a drawing so I hope my description is not too confusing.
The main advantage of the aquaarm is that the entire mass of the tonearm is on the water surface and moves on it, that is, friction occurs only on the water, and two wheels take the load only from the plate track pulling the float.
The float can be located anywhere in the aquarium, but when you put the tonearm on the going track of the record, it is instantly attracted to the glass wall through two wheels and its geometry takes the shape of a triangle we need, and this is the pickup needle and two wheels adjacent to the glass wall of the aquarium.
This scheme is extremely simple and I believe that it should not be complicated.
In this scheme, you did not take into account the main force of the aquatank.
This is the force of the walking track that will pull the tonearm forward.
Hi folks, consider that with a conventional tonearm it is widely accepted that insufficiently stiff bearing mounts blur the sound, then the movement of the float in water will be far greater, even though indiscernible to the naked eye.
By the way, my proper job involved understanding water and floats for decades as a naval architect, so its an area with which i am familiar.
However, there will be compromises in any design and it may be possible to eradicate some and improve matters or it may be that the arm is already as good as possible for its type.
In a previous post i attempted to describe some potential areas of movement, the idea was that thinking about these would help ideas evolve.
Let's take one here, if movement of the float in rotation might be a problem as shown above let's consider how that may happen. the stylus and its pivot apply torque to the wand which is attached to the float, looking down on the apparatus this is resisted by the stylus drag pulling the whole thing against the basin wall, this appears to work and it would be certain that the more widely spaced the basin wall wheels are the better it would work, my experience shows this would be easily measurable with reduction in sidebands on the measured tone and audible as well. Try spreading the wheels along the float. By the way the longer float will behave better in many ways, the waterplane area should be spaced away from the wand.
Then take a look face on with the cartridge, if the vertical centre of gravity of the whole moving part and the waterplane of the float and the stylus were all in one horizontal plane then the torque to move the float would be zero, again i would expect a measurable and audible improvement. Maybe they already are this way, but the arrangement doesn't look like it.
Just ideas!
M
I understand that the groove will pull the arm forward. The question is if the base is yawing under the eccentricity of the record. If both front wheels have solid contact with the wall of the water container all the time even under the eccentricity of the record, my previous diagram is invalidated. In other words, the arm is not yawing.
The video doesn't show it. My suggestion is to take off the cover, play an eccentric record, and watch both front wheels. If both wheels contact the wall simultaneously all the time, it indicates that there is no yawing.
Similar floating tonearm has been discussed in this forum in another thread before.
https://www.diyaudio.com/community/threads/floating-tangential-tonearm.339309/
https://www.diyaudio.com/community/threads/floating-tangential-tonearm.339309/
How quickly time flies, 9 years have passed:
https://hi-fidelity-forum.com/forum/thread-81833-post-1652048.html#pid1652048
https://hi-fidelity-forum.com/forum/thread-81833-post-1652048.html#pid1652048
Hi Jim,
One of the standard specifications listed for air bearings is stiffness. It is measured in exactly the same units as used to define the rate of springs. The way an air bearing is measured is how much force is required to compress the air gap by a unit amount (lb/inch, N/m) at a certain air pressure. This is measured for moving the entire bearing perpendicular to the shaft. In our case the load we are most interested in is not perpendicular to the shaft but is a twisting parallel to the shaft with one end moving forward and the other backwards about the centre point. The bearing will be less stiff with this type of loading. This is not a static force but an oscillation at the frequencies of the music being played so occurs across the audio band. In combination with the moment of inertia of the carriage the stiffness of the air gap will result in a resonant system. As the moment of inertia of the carriage is low and the stiffness of the bearing high, even in torsion, is high the resonant frequency will be high. It will depend on the weight of the carriage, the size of the bearing and the supplied air pressure. A lighter carriage with a bigger bearing and higher supply pressure will result in a higher resonant frequency which is desirable.
Niffy
Also, the load on the bearing depends on the modulation of the groove, the more bass, the wider the modulation, respectively, the load will be greater on the bearing. In short, the load on the bearing is not static, but variable.
Knocking could be mentioned in this regard, since such moments with the modulation of the groove affect the ability of the disc to maintain the desired rev stabilization.
Hi Niffy,
Although the measurement unit is the same as springs for air-bearing, it doesn't mean air-bearing is a spring. Take my air-bearing arm as an example. The load is about 95 grams plus the weight of the air bearing itself, 80 grams. No matter how you want to move the air-bearing. The load is always the same, 95+80 grams.
Let's split hair here and assume that the arm is 42 lbs. So the load is the maximum load an air-bearing can take. Under the maximum load, the compressed air inside the air bearing may have very very small amount of so-called "springiness". For such a heavy load and such tiny small "springiness", what is the resonant frequency? I don't know. It must be way way out of the music frequency range.
Now, let's look at the actual air-bearing arm as mine, it is only 95 grams load. 95 grams for air-bearing which can load 42 lbs is close to nothing. It is just like a person who tries to push a 1000 lbs object. What will happen to the object? Nothing.
The resonant frequency will not change with music passage. For a particular mass and a particular "springiness", there is only one corresponding resonant frequency just as we calculate tonearm resonant frequency. There are only two factors, i.e., effective mass and compliance, "springiness".
Since a load of a tonearm is so light for an air-bearing, its impact is nothing at all. Therefore, the compressed air won't act as a spring. It is an objection to air-bearing arms, at least, for my style of air-bearing arms.
Jim
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A load on an air-bearing is a constant mass. It doesn't change with the modulation of the groove.
I didn’t talk about the mass, but about the force pulling the tonearm forward in the direction of the track, with an increase in the modulation of the groove, the force will increase, that is, it is variable, which means that the load on the bearing in the horizontal plane will be variable.
I am pleased that such areas are being explored here, it can help my understanding, and that's the fun of diy audio!
I believe it would be universally accepted that the mount of any type of arm should be as rigid as possible including through its bearings and allow any micro vibration generated from the cartridge body to pass away from the cartridge and eventually be absorbed or changed into other forms of energy, that means such vibrations are minimised in the arm and aren't reflected back to the cartridge and stylus where they can interfere with the only desired vibration caused by the stylus following the groove. These are micro vibrations, so any degree is undesirable.
This is easy to demonstrate with any tonearm, it already contains a useful apparatus to demonstrate this. Just place the stylus on a stationary record with the rest of the audio chain switched on and go around the tone arm mount area and tap it all very lightly, taking great care to not damage anything. There will be no visible movement, but from the tiniest of taps a massive boom will come out of the speakers in comparison.
From this we can understand that tiny amounts of spring, vibration, movement etc really matter, good arms are good because they have avoided big problems, great arms have to address the areas of micro vibration as well, and it is in this area i would like to know more about the aqua and air.
For sure this will be something that can be measured and calculated and comparisons made. It may be that the resistance to a defined load of the air bearing is theoretically greater than the aqua arm, maybe not, so why does Havuns aqua sound better than his air bearing one.
However we are talking micro loads here (as long as the whole assembly stays together in use that's the only need to cope with large loads)
Maybe at a micro level the aqua is stiffer than the air?
Understanding the reasons can help us develop further.