Spiral Groove Centroid tonearm

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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Haven't heard it but I want one!

I'm going to try and not be promotional here. If I fail at my attempt, I sincerely apologize. I want to reinforce what Jonathan mentioned about the overhang alignment arrangement when using the Centroid and the new Delos or Kleos. In the case of the Centroid, we include an alignment system that provides exact stylus to pivot positioning of the alignment protractor using the locator hole on the headshell, which will also accommodate for the particular cartridge height (which will change the stylus to pivot point distance) with a height adjustable locator pin mounted on the protractor. When using the new generation Lyra Delos or Kleos, the alignment protractor isn't really needed unless you want to perfectly align the cantilever to the protractor within the deviation of the screw diameter to the headshell slot spacing. Don't get me wrong, zenith is a critical alignment, but I find that visually aligning the cantilever to a protractor is usually only good for a consistent zero point from which to do the final dial in by ear. There is a patent on this locator hole system but the patent is really only to maintain a standard. I know that Allen Perkins invites all cartridge and tonearm manufacturers to use this system in an effort to standardize and make set up easier. Credit must be given to both Jonathan and Allen for their conceiving and executing on this system. It is in the spirit of furthering the art and not market competition. To answer the questions about the Centroid and azimuth stability, the goal was to significantly reduce the moment of inertia and therefor its effect on the cartridge cantilever/suspension system. It is a classic unipivot and the stability goal of the arm is actually in the name. Allen has designed the counterweight to place the center of arm mass at the pivot point (where the pin and jewel cup meet) . In other words, the arm functions on the centroid of the mass. (Centroid; def. - That point about which the static moment of all the elements of area is equal to zero) Of course, the center of mass will move relative to the pivot point depending on the position of the counterweight. The Centroid has a stainless steel counterweight that is quite heavy and wraps closely, forward, and low around the pivot point in such a way that very little movement is required to accommodate a wide cartridge weight/stylus pressure range up front. With the center of mass always located extremely (extremely) close to the pivot point, the moment of inertia is very low and the stability of the system, in all planes is very high...when the stylus is at the record plane. The very low and consistent moment of inertia due to the consistent proximity of the center of mass to the pivot point provides a system that allows for the use of low weight/high compliance and high weight/low compliance cartridges. I'm afraid I've already stepped over the boundries in my explanation so I had best stop here, and I'm sure I've just raised more questions than answered those above. There are a good many details beyond this description that I think are more appropriate for a manufacturer sponsored information site. Again, my apologies of I've come across as promotional.
cheers, Stirling Trayle

I failed to mention...
Mark Doehmann, Director of Research and Development at Continuum Audio Labs must be noted as well in regards to the concept and discussion that led to the stylus locator hole system mentioned above. I believe Allen, Jonathan, and Mark were sitting around after a trade show chatting about things analog and this was one result. Woulda been fun to sit in on that one...

Thank you so much for the write up, Mr. Trayle. No apologies needed. That's the kind of info I was looking for and it couldn't be better. You managed to talk about all the design features without lapsing into even one sentence of pornographic sonic description. Bravo! You have no idea how sick I am reading reviews about how "neutral" or "musical" a device is without any analysis of its function and mechanics. Just for that, I applaud you.

The said alignment arrangement is a great idea and I wish more manufacturers can adopt that in the future and, hopefully, it can be standardized among cartridge and tonearm makers. ANYTHING getting the alignment close to the ballpark is better than nothing. All it takes is two tiny holes, one on the headshell and one on cartridge body. Hey, why not!

Thanks for the explanation on the centroid concept applying to the arm pivot. Does the arm still retain the design feature in the Immedia arm like adjusting VTA WITHOUT moving the pivot point? Judging by the picture, the set screw in the middle of the bearing housing appears like such mechanism. I always find that a very unique feature in the Immedia arm, even though the VTA obsessives might complain about the lack of on the fly adjustment - not surprisingly they are usually unipivot users because, I believe, typical (not all) unipivot arms inherently require mass below center of gravity to be stabilized and its pendulum effect can affect VTF, hence sensitive to VTA adjustment. The Centroid concept probably helps in that department. Does it have VTA on the fly adjustment, then? No big deal to me, I rather be listening to records than constantly fuzzing over VTA. Speaking adjustment, how is azimuth adjustment achieved? Another question is damping. Does it have fluid damping like the Immedia or any damping at all?

Don't worry about being promotional. I am sure prospective buyers are more than happy to find out all the design features than not. Your write up is professional, informative and, to me, educational. Thank you for your time.

I am tickled by the story that a bunch talented designers from competing manufacturers sitting around "chatting about things analog" and coming up with ideas that can benefit audiophiles "in the spirit of furthering the art and not market competition." It is this spirit I wish to see more in the forum world.

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