How Close is Close Enough? The Acoustical Systems SMARTractor
ake a look at any mechanical process and it becomes pretty obvious pretty quickly that it depends on precise tolerances for smooth, predictable and repeatable operation. Something as crude as a winch mechanism still needs precisely meshing gears if it is to work properly. Reduce the scale of operation down to the size of a wristwatch and you are into microscopic tolerances and assemblies, where any deviation causes an instantly apparent error in the output -- the accuracy of the timepiece.
The act of dragging a microscopic stylus down a tiny groove might not seem like the height of refined mechanics, but consider the scale of the elements involved and the precise geometry that governs the process and it soon becomes apparent that as crude as the mechanism is, to work properly (arguably, to work at all) analog playback requires seriously precise alignment of the various elements involved: the record, the tonearm and the stylus. Any non-tangential tonearm traces a curve across the record, a curve that deviates from the straight, tangential path of the original cutting head. The longer the 'arm, the shallower the curve, the lower the deviation. But long 'arms take up space and inevitably have higher effective mass, both undesirable attributes. So instead, by carefully combining a manageable 'arm length with a fixed offset angle, manufacturers are able to create a shallow arc based on a virtual pivot point that equates to a far longer 'arm. Put the 'arm in the right place and youll actually achieve two points of true tangency to the groove as it traces the record, with varying degrees of error between them and to either side (which is why tracks two and four on a standard five- or six-track LP side so often sound the best).
Of course, being audio, nothing is ever quite that simple, so there are a number of alternative calculations that seek to balance the position of the null points against the accumulated distortion for best overall effect. Even a quick examination of the subject will throw up the names Loefgren, Baerwald and Stevenson, each with its own associated geometrical solution.
Ill come back to the various curves in a moment, but for the time being lets accept them as evidence that, in what is essentially a geometrical solution, cartridge alignment matters. In fact, the old Elite alignment protractor used to offer a percentage error reading, based on tangency at any point across the record -- with pretty frightening results. The lesson was simple: Time spent on getting cartridge alignment spot on was time well invested, resulting in an all-too-audible reduction in distortion and an equivalent increase in musical engagement and communication. The question then becomes, how best to achieve perfect alignment, a challenge that encompasses the dual problems of methodology (how to do it) and execution (the best tool for the job)?
In this case, with a few minor variations, the methodology is firmly established. It takes the form of some kind of protractor, a template that fixes the position of the cartridge relative to the record, normally with reference to the spindle. In a situation where the tonearm and cartridge are clearly defined, its possible to produce a full curve, normally with associated tangency markings at the appropriate points for whichever geometry has been adopted. You can see this in the combined Linn protractor/strobe disc, made possible by the virtual "closed loop" of the LP12 product family, and also in the form of bespoke products like the Wallytractors. But any universal solution needs to reference both the spindle and the tonearm pivot point. There have been various iterations over the years, all variations on the theme of an L-shaped device that sits over the spindle, with a variable-length outrigger that locates the tonearm pivot point and sets the precise angle of the alignment grid etched or printed on the plate set at right angles.
These days the benchmark product is the Feickert NG Protractor, a simple and extremely cost effective solution that offers users universal alignment of all three major geometries (Loefgren, Baerwald and Stevenson) for cartridges mounted on 'arms with a pivot-to-spindle distance between 180mm and 320mm. It's a tool Ive used with considerable success for several years now. Its got the methodology down pat, so any alternative is going to have to offer improved execution.
Which is exactly where the SMARTractor comes in. It is produced by Acoustical Systems, a small German company that specializes in analog-related product solutions, including the Arché headshell and the fascinating Axiom tonearm, both reported on for our Munich coverage. I'm a Fidelity Research owner, so the Arché headshell was a sight for sore eyes, and Ill be reporting on that shortly, but first lets start by looking at the aforementioned SMARTractor, middle model in a range of three alignment devices. The UNI-Protractor is described as a "professional-level" alignment protractor offering the highest possible degree of precision. The UNI-P2S is a separate device for accurately setting pivot-to-spindle distance when mounting tonearms (to within 0.05mm). The SMARTractor combines both functions into a simplified single-point alignment tool suitable for audiophiles to use at home. Its reason for being, over and above a product like the Feickert, is the increased precision that it offers, a result of the way in which it has been put together and the facilities it provides. But in order to judge the significance of those refinements, its necessary to first gauge the scale of the problem.
Acoustical Systems chief engineer Dietrich Brakemeier describes it thus: A 12" tonearm has an effective length of around 300mm and supports a cartridge whose stylus contact patch with the groove wall should be between 2 and 6 micrometers. Thats so tiny that its hard to envisage, so lets blow it up to real-world dimensions, 1000 times the size. Now, our tonearm is 300 meters long (330 yards) while the cartridge, rather than 25mm long is now 2.5 meters or 8 feet in length -- the size of a compact car. Whats happened to size of the contact patch between the stylus and the trench it is now running in? Its 1000 times the size, making it anything up to 6mm long! Thats a 6mm contact patch hanging on the end of a 300-meter beam. Suddenly the notion of precise alignment takes on a whole new meaning.
How does the SMARTractor seek to improve its precision? Its simple really -- it does it by improving tolerances and adjustability. For a start, you get three different spindle adapters, with 7.1, 7.15 and 7.2mm holes to ensure a precise fit over the platter spindle. Reducing play and the resultant imprecision at this point is crucial, whereas nearly all other protractors use oversize holes to ensure that theyll fit all available decks. Second, the extending beam that fixes the pivot distance (used for both the pivot-to-spindle function and to align the protractor) runs under a clear acrylic screen with a hair-thin graduation line -- an extremely accurate reverse Vernier scale -- for reference. This makes the precise setting of pivot-to-spindle distance (up to 315mm) simplicity itself. Third, as well as offering five different geometries in both DIN and IEC configurations to suit different tonearms, the SMARTractor also includes a magnifying loop, so that you can actually see the position of the stylus tip on the grid, as well as the angle of the cantilever relative to the grid lines. The fine lines of the CNC-etched grid and mirrored surface of the protractor make visual assessment significantly easier, while the provision of the loop means that you can actually see whats going on with a clarity that makes past experience seem like groping around with a torch in an unlit coal cellar. Of course, some cartridges are far easier to work with than others. The van Den Hul and Lyra designs, with their prominent cantilevers stretched out in front of their bodies, make life easy. Koetsus and other box-bodied cartridges are far harder to work with, but again the SMARTractor promises a significantly enhanced view of proceedings.
Collectively, these changes might not seem that significant, but in practice the increase in precision is readily apparent. Theres a confidence to the handling and operation of the SMARTractor that encourages care and precision, while its single-point alignment system is certainly simple and incredibly intuitive to use, arguably eliciting better performance from the operator that will in turn be reflected in the performance of the player. After all, a more precise protractor will only offer superior results if the person doing the alignment can achieve greater precision as a result. Does it offer consistently better musical results than the Feickert (in the way the Feickert audibly betters other devices)? Only time will tell, and well get to that in the course of a full review. But the provision of both Loefgren and Baerwald geometries to both DIN and IEC standards (meaning that alignment can be optimized by type of record/groove area and origin of tonearm) as well as the mechanical refinements means that the knowledgeable practitioner should be able to achieve a far higher degree of geometrical optimization, especially in a scenario involving older tonearms and records.
Which leaves arguably the most interesting facet of this design til last. The fifth geometry is Brakemeiers own, dubbed UNI DIN. It is specifically calculated to offer reduced distortion over the latter half of the record surface, particularly important when playing records that run the cut grooves close to the label, with a very short runoff -- exactly the style of cut so often found on the most collectable Deccas and other early pressings. Throw in the fact that the vast majority of classical pieces end on a musical climax and the significance of improved tracing of those final grooves becomes only too apparent (Brakemeier claims between 18 and 45 percent lower distortion across the final two-thirds of the record when compared to Loefgren or Baerwald). Putting those claims to the test is going to take some time and effort, but for now initial impressions of the SMARTractor are extremely positive.
At 449 ($650 in the US, available from VANA Ltd.), the SMARTractor looks like a bargain compared to its big brother, the 795 UNI-Protractor. Clearly, such precision doesnt come cheap, but compared to the price of a top-flight pickup or two, it constitutes a realistic running cost for any audiophile with multiple decks, 'arms or cartridges who likes to set them up himself. As a tool it also promises serious benefits to any dealer or reviewer who works regularly with analog front-ends. Just how big those benefits might be -- and how beneficial the various different geometries prove to be in practice -- remains to be seen, but previous experience with the Feickert suggests that the musical improvements over lesser protractors could be far from subtle.
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