Axelwahl: The Dorian is designed to have a mounting screwhole to stylus distance of 9.52mm (3/8 inch - not 5/8 inch which would be 15.875mm!). All of the present Lyra cartridges are made like this, with the exception of the Helikon (the oldest design in our lineup).
The Dorian's mechanical components are milled on an NC system, so even given component tolerances, it would be impossible for the 9.52mm dimension to be off by more than +/- 0.3mm.
Also, assuming for a moment that the Dorian was indeed considerably shorter than 9.52mm, the mounting screwhole to stylus distance is not a dimension that should change with a retip; unless the retip involves rather violent measures (grin).
In any case, Axelwahl, your story doesn't (yet) make sense to me.
As an aside, the suspension and dampers of an MC will gradually degrade with use, and should properly be replaced together with the cantilever system when the stylus wears out. Restated, a cartridge should be rebuilt rather than retipped when the stylus wears out.
However, no cartridge manufacturer that I am aware of is in the habit of making any of their components available to outside retipping companies (and none of these components are standard off-the-shelf parts).
Also, even for the original manufacturer, it takes time to understand the intricacies of a specific MC design and how to make it work at its best. Much of the prototyping cycle of a new cartridge model is focused specifically on that aspect - the design will be built and rebuilt in dozens of different ways until it can be figured out how to extract the maximum possible amount of performance from it.
Therefore, unless an outside retipper has a specific agreement to receive authentic rebuild parts from the original manufacturer, and has undergone a hands-on training program dedicated to that design, for him to rebuild an MC faithfully is an impossibility.
hth, jonathan carr |
Giggsy was referring to the Clavis DC. This is a far older design (its replacement was the Helikon, which itself has been in production for 10 years).
Your situation starts to make a bit more sense, Axelwahl, thank you.
But if you had a chance to compare the Allearts retip (which you said was closer to 9.52mm) to a stock Dorian (which I designed for 9.52mm) and found the retipped version clearly longer, again the numbers don't add up. The only plausible scenario that comes to mind is if the "stock" Dorian that you compared the Allearts-retipped cartridge to was actually not stock, but had been retipped with a shorter cantilever.
FWIW, I've had Allearts cartridges, and didn't consider the cantilevers to be so different in length from what I use, so I doubt if a Lyra-made Dorian would be much shorter than an Allearts retip.
BTW, we don't do retips. Only head-to-toe full rebuilds that involve complete replacement of all wearable and cosmetically blemished parts (although more than a few cartridges that come back to us only need a good cleaning and mild readjustment, rather than a rebuild). From what you have said, your Dorian would benefit from a proper rebuild (sounds like it has had a _very_ hard life).
regards, jonathan carr |
Raul, first we should ask if most cartridge manufacturers give much (if any) consideration to the IEC standard, or are even aware of it as a standard. Second, in reality it isn't easy to make each and every cartridge design accomodate a mounting hole to stylus pitch of 3/8 inch, and the greater the differences between a cartridge designer's individual designs, the harder it becomes to maintain 3/8 inch.
Some companies have exhibited little design variance in the cartridges that they have launched over a period of years, but others have shown major variances. I'm one of those who tends to make pretty radical changes between designs (or design generations), and I'd suggest that Dynavector is another such company.
I started out over 25 years ago with cartridge designs based on a classical-style single big magnet plus two polepiece (yoke) arrangement, but today my designs have evolved to two small magnets and no polepieces (with the exception of the Olympos, which is based on a platiron magnet that demands polepieces to function properly). The physical length occupied by a single big magnet plus two polepieces is _very_ different from two small magnets and no polepieces, and this is particularly true for magnets that prefer to be used long, such as alnicos and platirons. Such magnets require a long cartridge body (look at a Koetsu from the early 80s to see what I mean), and make it difficult to keep the mounting screwholes close enough to the stylus position. Now if I were to design something like the present Lyra designs but with a 1.7mm cantilever like a Dynavector DV17, I'd have the oppposite problem, and would need to integrate some kind of extender (like a stretched limousine) into the cartridge body to push the stylus sufficiently foward of the mounting screwholes.
The cartridge body outline (as seen from above) also turns out to be an important factor; cartridge bodies that remain square out to their corners are the most flexible because they give the designer maximum freedom to change the locations of the mounting screwholes without alteration to the other dimensions. In contrast, the signature Lyra body shape isn't well-suited for long magnet structures, because the angled corners midway along the cartridge body make it impossible to bring the mounting screwholes any farther forward.
IOW, 3/8 inch works well for some kinds of designs, but can be an ordeal and constraint for others ;-). I have been willing to adjust my designs to accomodate the 3/8 inch standard, but doing so has been tough going at times, and has definitely created a lot of extra work. If I didn't firmly believe in the importance of at least some kind of standard in cartridge dimensions, I'd likely disregard the IEC standard as being an unnecessary constraint on my design freedom.
When (not if) the 3/8 inch IEC standard is an impediment to cartridge design, it is understandable that some cartridge designers may choose to ignore it because it increases the design effort required and makes their work more difficult then they care to justify.
FWIW, based on engineering drawings that I have seen, even Ortofon doesn't always adhere to the IEC standard.
regards, jonathan carr |
Fair enough, Axel. Thank you.
BTW, please note that applying tracking force to a cantilever will extend the stylus position forward by a small but noticeable amount. This is why Bob Graham's gauge uses a see-through crosshair piece that is weighted, to ensure that the stylus receives enough vertical force to shift it into the right location.
Ideally, Bob should add some kind of force or weight adjuster to his gauge so that it can be dialled in precisely for cartridges that have different tracking force requirements. Also there should be some type of height adjuster to enable the crosshair piece to remain in a horizontal state regardless of the cartridge height. But this, I suppose, belongs in a different thread - perhaps "Will Grahams, etc benefit with....." ;-)
regards, jonathan carr |
Mike, it sounds like the base of your Skala has been pushed backward relative to the pillar, probably during a mounting/unmounting operation. Unlike any of our other cartridge models (which are all monolithic structures), the Skala employs a two-section structure which is comprised of a small-footprint vertical metal pillar (which the cantilever assembly is mounted to, and a larger-footprint horizontal polymer base which carries the mounting screw bosses. A slide-and-rail system friction-fits the two sections to each other, thereby providing a relatively lossy interface (and therefore greater mechanical damping), but the downside of such a system is that under certain circumstances the sections can move slightly relative to each other.
Once the mounting screws are torqued down, they cause the polymer base to compress and bend, which then pulls the footprint of the vertical pillar firmly against the headshell surface so that everything is locked in position and cannot move. But if the polymer base is pulled or pushed before the mounting screws are in place and properly torqued down, it is possible for it to slide fore and aft. There is a built-in stopper to prevent excess base movement, but the base can slide a little before it hits the stopper. Mike, if you have measured 10.5mm from mounting screwhole center to stylus, it means that the polymer base has been pushed back relative to the metal pillar and should be pulled forward a little.
It is possible to pull the polymer base back forward, but you need to be very sure and very careful when doing this - otherwise there is a good chance that you will break the cantilever. If you want to try to nudge the base back to where it belongs and feel that you are up to the task, send me an email and I will think of a suitable way to describe the procedures that you need to take, with as little hazard to the cantilever as possible.
I am not going to post this information publically, because someone is going to follow the instructions, make a mistake and trash the cantilever.
FWIW, the exact location of the polymer base means absolutely nothing for the sound and performance (the Skala can play happily without any base at all), but for easier setup with arc protractors, it is better that the base is in the right position.
regards, jonathan carr
PS. Is anyone familiar with the Max Townshend gauge (US patent 166,447)? The actual gauge is a little different from the patent, primarily in how the error lines are defined. The patent shows straight error lines which indicate the error amount in degrees, while the actual gauge has curved error lines which indicate the error amount in distortion percentages. I find this tool to be quite useful, and extremely versatile (even when the hole for the arm pillar has been drilled in the wrong location, or the geometry data for the tonearm is missing). |
Raul: Yes, I think that to insist on 9.52 would be a severe limitation on cartridge designers. I can easily envision configurations which would tend to be shorter than 9.52, and I can envision configurations which would tend to be longer, too. Of course, if cartridge designers all avoided architectural diversity and only used configurations which fit into the 9~10mm range, 9.52mm would be OK (grin).
One other major variable is the rubber damper systems used in most cartridges. In the small sizes used in cartridges, rubber is not a very consistent material. The characteristic that you are looking for primarily from a damper is consistent damping behavior, but due to the variable nature of the material, consistent damping behavior is not the same thing as consistent thickness, or even consistent pressure. When I was just starting out in cartridge design and still inexperienced, I thought that a consistent pressure system would be perfect for adjusting the dampers and suspension, and would make a major step towards consistent dimensions. So I designed a calibrated adjustable weight system to apply consistent pressure to the dampers and suspension during the building process, and instructed a batch of cartridges to be built like this. The dimensions were fairly consistent (albeit not absolutely so). However, the performance measurements were all over the place, really bad, and that batch of cartridges needed to be built again.
I learned the hard way that each damper is unique, it is better to let a trained and experienced cartridge craftsman adjust the dampers individually, and accept whatever dimensions that arise from this.
You can, of course, prioritize consistent dimensions (like I did decades ago), but most likely you will find that the cure leads to worse diseases in other areas.
One thing that I haven't seen yet in these threads is an effort to _quantify_ the change in distortion that will occur if a cartridge is not precisely 9.52mm, what happens to the distortion if the base is shifted backwards (assuming an SME), how much the headshell offset angle needs to be changed to compensate, and how much slack you need between the headshell screwholes and mounting screws to accomplish the requisite change in offset angle. Cartridge alignment is never going to be perfect - for example a Baerwald alignment only results in zero tracking distortion at two tiny places over a span of 100mm or so. If we are going to talk about distortion, at least let us try to first quantify it, and then we can decide for ourselves if the level of distortion is acceptable or not.
FWIW, also note that some other tonearms with fixed screwhole headshells, like the Naim Aro, appear to have been designed with a much shorter cartridge in mind, From what I can tell, these were designed for cartridges of 7.5mm or 7mm pitch. The same applies to the Linn arms, if you use the third hole.
cheers! |
