Spiral Groove Centroid tonearm

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.

_____

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