SA-1.2 / SA-1.2B



Produsent: ABIS

Pris: 17900 / 20900 (sort)


Beskrivelse

Flott håndlaget tonearm fra Japan som er mellomtung/tung.

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The SA1.2B is the black version of the SA1.2, and all other specifications are the same.  

With the introduction of the SA1.2B tonearm, along with the improved SA1.2, Abis has improved the performance of the original SA1 tonearm, already recognized by Stereophile as a meritorious design.

 Though current Abis SA1.2 arms are substantially the same as the first version of the SA1 tonearm, the refinements in bearings and geometry improve on the performance of the original.  The result is an arm with substantial authority, the same as the original arm, but with even greater refinement and delicacy.

Key to the performance of the SA1.2 and SA1.2B is the use of very high grade ball bearings. Bearings used for horizontal movement are axial-loaded, angular-contact, thrust-bearings. These thrust bearings have zero play and are held in contact by gravity.  You can think of them as acting like a unipivot, but with more than one contact point.  Because they have two tapered seats, they will self-align in the presence of a load (gravity), have exceedingly low moving friction and are especially suited to angular and axial loads.  

The angular error needed to misalign these special bearings, commonly used in high precision machinery, are so severe that they fall well outside the operating conditions for a turntable (if you need an arm for playing in zero gravity, or turned at 90° to earth’s gravity, you will be forced to use a different style of tonearm).  Traditional deep-grooved ball-bearings are not specifically designed to take an axial load, being better suited for radial loads like a wheel bearing, and they suffer from much higher rolling resistance.  While the quality of the bearing materials are a key to success, the proper choice and loading of bearings is just as important.

angular contact thrust bearing

Angular Contact Thrust Bearing

 

 

High Precision Radial Bearings

 

Also key to the performance of all tonearms, and especially the SA1.2 and SA1.2B, is the resonance characteristics of the arm “tube”.  

The SA1 design is built from four pieces of billet aluminum, milled to tight tolerances, finished, fitted by hand, and torqued to settings determined by experimental observations.  The torque values chosen introduces preload on the fasteners, and produces hysteresis stresses (basically, inner friction) in the crystalline structure of the metal.  These stresses damp vibration by forcing the crystalline structure to be more tightly bound, than when in a free state.  The elastic and anelastic properties of all four pieces are slightly different, preventing dominant acoustical nodes from developing.

When properly machined, fitted and torqued, a unit composed of several milled pieces will have lower maximum resonance, with several smaller resonance frequencies, compared to an armtube composed of one piece.  These statements are backed up by scientific study into weapons systems, rockets, engines, structural elements, etc..  

Resonance is a key source of failure, and the research proves the point:  a single piece of billet material can have 1~3 dominant resonance frequencies, with one resonance frequency dominating the performance of the structural member. If you think about the bars that form the notes on a xylophone, you will have a practical understanding of the limitations of “one-piece” arm tubes.

 In practice, a combination of surface finish, damping materials, shape, density, alloy, crystalline structure, fastening technique, and fastener preload, among others, will determine the relative distribution of acoustic energy in a tonearm.  

Since extremely dense (heavy) materials, like depleted Uranium, don’t easily lend themselves for use in tonearms, a holistic approach is necessary.

The rectangular shape, the tight assembly by hand, and the nature of billet aluminum creates a low-resonance design that is essentially quiet.  

The preference for 12″ arms has more to do with compliance match, than the theoretical advantages of a 12″ arm (which are nullified by the use of a spherical tip).  The SA1.2 and SA1.2B maximize the possible geometry at 9.4″, while excellent damping and high mass give it the tonal balance of 12″ arms.  

With the SA1.2 and SA1.2B, the tracking error is very low, while the superior sonic signature of the billet aluminum arm parts, and the mass equivalent to most 12″ arms, gives 12″ arm sound in a compact form.  It is ideally suited for low to medium compliance cartridges, especially those that are particularly problematic when it comes to mistracking.  

 



Spesifikasjoner

・ The major key to tonearm quality is the sensitivity and stability in retrieving delicate signals, for which the bearings are the determining factor.

The SA-1 employs miniature radial bearings for both horizontal and vertical movement. Very high performance is achieved at a reasonable price. ・

The rectangular arm-wand is machined from a solid aluminum block having an  advantage in rich and tight bass reproduction, as bass sound is mainly recorded in  the horizontal plane of the groove. ・

Tonearm wires run through separate aluminum tubes inside the arm so that stereo separation is maximized. ・ Reproduced sound is precise and clean, thanks to hand assembly by highly skilled craftsmen. ・

Comes with detachable headshell, phono cable (RCA output plug, or optionally as XLR), screws, washers, wrench and marking pin.

Technical Data Length:

310mm Spindle center to arm pivot distance:

212mm Stylus to pivot distance:

228mm Overhang: 16mm

Cartridge weight: 15 ~ 45 grams, including headshell

Anti-skating Device Net weight: 745g (with headshell attached: 762g)

Custom made in Japan for: SIBATECH, Inc., Tokyo Japan