Linear tracking turntables, whatever happened?

Agreed about the Trans-Fi. Not only is it a good air bearing design, so the lateral forces acting on the stylus are negligible (think about the mechanical advantage of a spiral a meter long, acting over the width of a groove - a distance measured in micrometers), but it’s adjustable. As adjustable as any arm made, and that alone makes it a contender.

Let’s talk about adjustability. Tangentiality - fiddly, but perfectible. An old record, a good micrometer, a bright light, and half an hour. Mass - just add brass weights to the conveniently space holes. Resonance - lay Moongel or Sorbothane on the flat surfaces, as much or as little as required - as required for your cartridge and your taste.

VTA adjustment on the fly - and so easy it’s trivial. VTF a bit crude and fiddly, not on the fly, but intuitively obvious. Azimuth is the toughie - fiddly, but intuitive and very stable. Thing is, you start where most others end - and you end with 1 or 2 minute of arc precision (with a mod - see below).

Forget about overhang and choose-your-poison protractors which pretty much get it right - for parts of the record. And forget about almost-right-I-hope anti-skating. Instead, rejoice in Vic’s measurement about forces acting on the stylus - tonearm wire dominates.

Add the clever engineering which makes use of standard parts instead of precision machining, and you have a low-cost ultra high end device.

Is it perfect? No. The beam is cantilevered out, and so it’s just as unstable as other air bearing arms (that is, not very, but a little). The beam should hold adjustment to a few minutes of arc for perfect horizontal orientation. It doesn’t - it’s only stable to about 10 minutes of arc, but on the other hand, it’s a predictable amount in a predictable direction. I’ve built a support for the other end of the cantilever, and it solves both issues.

The vertical pivot is higher than the stylus by a centimetre or more. That means slightly compromised performance for warped records. The wand is only 70mm long, which accentuates the problem. On the other hand, the wand is only 70mm long. So that’s a tradeoff. In practical terms, it affects about 3% of my records negatively and 97% positively.

Last, there is a very minor aberration in air pressure on the saddle, for a few seconds, three or four times per side. The only cure is going to be an amorphous carbon bearing - costly, clunky, high pressure, and probably custom. But if I do that, I suspect I’ll have the best, most versatile cost-no-object tonearm in the world.

Or, you could settle for $15,000 performance for $1,000.

System - DIY air bearing TT, Koetsu, DIY electronics, ESL’s.

Not necessary to constantly fiddle, with the Trans-Fi at least. However, most fiddles bring a reward, so the temptation is there. Also, with the Trans-Fi adjustments are stable, rather more stable than most conventional arms I have used.

@harold-not-the-barrel 

Good questions. Yes, I support the manifold with an arm bolted to an aluminum column, bolted to the plinth. Actually, I designed my TT to accept this mod, and so the air thrust bushing supporting the platter sits on a panzerholz plinth which is fixed to big blocks of steel. The aluminum column is bolted to one of these steel blocks. The Trans-Fi is bolted to the panzerholz plinth through another aluminum column.

The manifold is slightly extended with a machined aluminum piece which is epoxied into the vee of the manifold. This machined piece has a protruding shelf which accepts a #0-80 screw, which touches the new supporting arm. A 1/16 turn of this screw adjusts height by about 20 microns, acting over a distance of about 30cm (screw to manifold pivot), corresponding to an angle of 0.00007 radians, or about 15 seconds of arc. In practice, I use only about half of this resolution, so adjustments are +/- 30 seconds of arc, which is sufficient. The settings are stable.

I haven't found it necessary to damp the Trans-Fi's base - I think that the air cushion covers that. But I haven't tried it, so I don't really know.

Nice talking with you, Harold. All the best!

Many propositions which do not prove the conclusion. The only relevant proposition is the existence of another thread, which proves little, and certainly not your conclusion. It's called a non-sequitur, Mr. Miller.

Pleasure is mine, Harold. Nice to share. And that Salvation's no slouch either.

I am certain that the improvement is a serious one, in my system. But indirectly.

The mod allows me to set the manifold with high precision and stability. Then I can set azimuth correctly, and THAT makes a big difference.

Trans-Fi tonearm works with low pressure. An aquarium pump is recommended. I run mine at 20-30mm of Hg, that is about 0.5 psi.

Low pressure means no issues with oil or condensate or maintenance. High pressure (for my TT) does mean maintenance, but industrial accessories and connectors limit that to an hour a month.

Ralph, the gentleman.

I use a HiBlo pump from Pets&Ponds. Model 60 I believe (massively overspecced because I planned to use low pressure for other uses). I use a 1 gal plastic jug filled with cotton balls, with a long piece of perforated plastic tube feeding air to the inside of the jug. Then a Fairchild precision regulator and a medical blood pressure gauge to get me down to the 10-50 mm of Hg range (sub 1 psi). I finish with a 5 gal Jerry can surge tank.

Vic's silver wire is very nice - very pliable, very euphonic. I use ETI connectors myself.

Moment of Inertia is denoted by I and is the angular analogue of mass. It is defined as the sum of (mass of molecule x distance to pivot squared). This is approximated by an integral (calculus), which is easier to calculate.

Thus, for a beam of just sufficient length and just sufficient strength to support the counterweight, the greatest Moment of Inertia I will be obtained by positioning the beam extending from the pivot parallel to an extension of the arm wand.

The obvious tradeoff is the amount of material required to position the beam that way.

There are other tradeoffs - one wants adjustability and rigidity and resonance control in the beam. Thus a system of a light but rigid tubing (say magnesium), with a lump of tungsten on the end, threading into a nut on the end of the arm, would give you the highest I/m ratio, but may be compromised with respect to resonance. I should try that on the Trans-Fi.

The description of sliding the record into place is perhaps inaccurate, only because it sounds tricky. It’s not tricky.

The record must held on a slight angle and inserted into the space between the manifold beam / cue bar at the top, and the TT platter / spindle below, then placed on the spindle.

It sounds much harder than it is. As soon as you have the arm fitted to the TT, it is obvious how to move the record. Try it with an old one first, or use a modicum of care, and everything will be fine.

If the spindle is short, that helps a lot, which is why I built my TT that way.

Clamps - the TransiFi manifold beam rides about 35 mm above the platter and 47 mm from the centre of the spindle. In my setup. Therefore, any weight < 88mm (3.5") of any height would fit.

Cartridges - I use very low compliance cartridges (Mayajima Zero and Koetsu) with the TransFI, but prefer the sound with a 2.9g brass weight on the nose of the wand, and a ’German silver’ (i.e. nickel brass alloy) 0.625" disk, with two holes drilled and tapped to accept the #3-56 brass cartridge bolts. This increases the mass of the tonearm and the rigidity of the cartridge mount. Also, I use MoonGel on every flat surface (wand and saddle) to reduce vibration.

I’ll host a thread on mods and setup after my construction project is finished (summer?).

@whart 
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