Unipivot vs Linear Tracking


I set up my first Unipivot arm night before last. It took roughly 5 hours to set up and I am still tweaking various parts and cartridge, what a work out. The arm is a Scheu classic with the Scheu Premier I turntable and a Scheu Benz cartridge.

Now I have two questions for the Audiogon club.
1. Do you consider linear Tracking superior to Unipivot?
2. Which would you say is harder to set up properly?
128x128spl
Like Albert, I've been through a few arms too. I like the *idea* of LT, and have had a few. But- I found myself preferring a uni-pivot (the Graham) and ultimately the Triplanar over that.

I still want to see an LT happen though. My feeling is that the air-bearing approach is fundamentally flawed, as the lateral tracking mass is several times higher than the vertical tracking mass (which is about the same as a radial tracking arm). You need a *really* low compliance cartridge to make that work, otherwise you get tracking distortion as the cantilever sweeps back and forth.

In addition, the more pressure you put in the bearing the better it sounds. Here is a fundamental rule about LP playback:

There can be no bearing slop between the platter spindle and the cartridge cantilever. The coupling between these parts must be absolute! (BTW, any of you that ride motorcycles will recognize this rule, it is the same one that says there will be no slop between the handlebars and the rear wheel, if you want the bike to handle safely).

Air bearings break this rule, as a result, you can always get them to sound *better* but you can never get them to actually work completely right- and so they can be shown up by a radial tracking arm, which simply should not be.

There is a solution. There are motion devices that have zero slop in their bearings. Some are small enough to be used easily in a tone arm, solving the Rabco track issue. One problem that the old Rabcos had was excessive slop in the track and there was nothing you could do about it (in addition there were a host of other problems- I had one of these for years and solved some of them, but some were fundamental to the design and could not be solved).

The kind of arm I am talking about currently does not exist. But- if you used one of these tracks and installed a modern arm tube/bearing system on it, and then an updated electro-mechanical means of arm advancement along the lines that Rabco made, you could make something that would work really well. I've been thinking about this ever since I got rid of my Rabco 20+ years ago... :)

Until then I'm using a radial tracking arm and its awesome. It is so nice to put on a record and not fear any tracking issue, any dynamic range; just have the music emerge (and buy more records) :)
There are extremely high tolerance, precision, liner bearings(air and otherwise) & linear motion slides used in optics & robotics/automation in semiconductor equipment, fiberoptics, photonics industries that would seem to be a perfect match for TT use.

As to whether they have been shrunk to a usable size or cost is another thing.
The physics regarding some weaknesses of linear design is plausible,but "man" do some of these things sound good!!!

Btw,I had a friend who owned,and loved,the "Versa".It sounded very good,but it almost never got through an LP without sticking,or something like that.So,I definitely buy into Atmosphere's comments.....as usual.

Best.
loved the "Versa" It sounded very good, but it almost never got through an LP without sticking, or something like that.

Humidity in the air would condense due to the high pressure in the Gast aircraft compressor used in the Versa pump. When this humidity filled the air lines it clogged the bearing and sometimes (literally) even dripped condensation (water drops) onto the LP from the air bearing surface. Obviously this is when it would stick.

The Air Tangent did not have this problem, nor did the Walker. Lots of factors go into each of these designs and even though I can still "hear" each one in my head, there are good and bad about each.
THK has a patented linear motion slide that is the perfect size for a linear tracker, has low sticktion and guaranteed no bearing slop. All one would have to do is put gimbled bearing and an arm tube, and...

I've stayed in the amp side of the business for a reason :)