Spiral Groove Centroid tonearm



Anyone has any experience with this new design? It has a rather brief rave review along with the Spiral Groove turntable in the latest Stereophile. It seems like an exciting analog product in recent years, along with Thales arms. Allen Perkins is a respected designer and I am intrigued by his tonearm design and wants to learn more about it.

From what I read, it's a unipivot design with a unique counterweight and bearing housing that concentrate most of the mass at the center pivot point, hence the name Centroid. I am also curious about how it deals with azimuth rocking in a unipivot design. Does it have a secondary ball bearing to stabilize torsional behavior like the Graham Phantom, Basis Vector, and Continuum Coppperhead, or the slightly different Nottingham and Simon Yorke? Or is it a pure unipivot with a spike and dimple? In unipivot designs, it is how the designer handles the azimuth rocking that truly shows the creativity. I'm surprised this tonearm has garnered much talk among the forum lurkers. If you know more about it, please contribute and discuss. Thanks!

Some pictures.
hiho
I am very curious on this arm to. Mostly b/c i love lyra cartridges and i assume this arm is really tuned/voiced with lyras in mind. Hope to hear it soon....
Both the Centroid and the new-generation Lyra cartridges (Delos and Kleos) were designed partly with each other in mind.

There's the obvious stuff such as working well together and sounding good, but there's another key feature, which is a built-in alignment method that should make life far easier when setting up a new-generation Lyra cartridge in the Centroid.

The headshell of the Centroid has a small hole drilled into it, precisely above where the stylus should be for optimal tracking. The bodies of the Lyra Delos and Kleos have also been drilled so they have a small hole in-line with the stylus location. The holes are sized to accept a 1mm or US 60 gauge (0.040 inch) drill shaft.

The concept is that you pass the blunt end of a 1mm drill shaft through the Centroid headshell and also partly into the body of a Delos or Kleos. This will align the stylus of the Delos/Kleos where it needs to be in the Centroid. Tighten the two 2.6mm JIS mounting screws, remove the drill shaft and the alignment is largely done (smile).

At the recent Munich High-End Audio Show, Stirling Trayle from Immedia brought a Centroid, and we brought a Kleos, and demonstrated the two together. My understanding is that the setup was a 5-minute affair, and that the other people in the room were flabbergasted at how quick and easy the process was.

Allen Perkins and I both believe that while it is important for tonearm and cartridge designers increase the performance potential of their products, it is equally important to make it easier and faster for the user to extract a higher percentage of that performance.

I will quote from the relevant section in the Kleos' manual (the manual includes drawings to make the process easier to understand). I presume that Allen must have a similar section in the Centroid manual.

"Kleos incorporates another, simpler stylus alignment method. The Kleos body has a 1.02mm hole drilled directly above the stylus, and this can be used with compatible tonearms, with a 1mm hole (US 60 gauge or 0.040 inch) drilled through the headshell at the position which gives optimal tracking of the stylus. Obtain a 1mm drill bit (or US 60 gauge or 0.040 inch), and push the dull end into the 1mm headshell hole so that it protrudes by 5~6mm from the headshell underside. Secure drill with clay or putty so that it doesn't slip (but can still move if pushed up vertically). Mount Kleos to headshell so that the protruding drill shaft fits into the 1.02mm hole in the Kleos body. Do this slowly and carefully, since you could scratch the Kleos body if you push or drag when it is not aligned with drill shaft. Once Kleos is flush with the headshell underside, install and tighten the two 2.6mm mounting screws. Feel free to also use a separate template to verify that cantilever is perpendicular to LP groove at null points (normally 66.0 and 120.9 mm from the LP center). Finally, remove drill shaft. This procedure should align stylus to an accuracy of +/-0.3mm."

hth, jonathan carr
Of course, I consider your Olympos cartridge to be among the finest in the world. That said, in a sense, isn't the alignment similar in ways to the tried and true alignment jig of times gone past? In the case of the Spiral Groove, precision is a given, and Allen's enviable six in-house CNC machines bring the concept to a new level. Still, what interests me most is the inertia concept of the tonearm. I belive, like Jim Winey, that inertia is the singular make or break component of any tonearm.

Regards,
Win
Saskia Turntables
The concept is that you pass the blunt end of a 1mm drill shaft through the Centroid headshell and also partly into the body of a Delos or Kleos. This will align the stylus of the Delos/Kleos where it needs to be in the Centroid.

Cool! I wish all cartridges and tonearms are standardized in such a way and would certainly save so much time for audiophiles.

Anyone else has more info regarding the arm design on features that Mosin pointed out such as its dynamic behavior, mass distribution, energy transfer, material, damping, pivot position, etc...? Mr. Perkins is a talented designer and I would like to learn more about his new creation as it, at least, appears to exhibit solid engineering and inventiveness.

From the look of it, I suspect the Centroid implemented some of the idea from his earlier design, the Immedia tonearm, which includes novel features like platter level pivot point with adjustable VTA at the bearing spike. The Centroid is probably a further refinement of the Immedia with new idea in handling inertia. Exciting! Also want to know if it uses a secondary bearing to stablize azimuth rocking.

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