Tobes, I think you miss the point of the SME's brilliant design when you say "as you no doubt realise, the SME V cannot be adjusted for effective length because of it's unslotted headshell mounts."
First of all, with an SME there is no need to adjust the effective arm length. With standard mount cartridges, the stylus/pivot distance will always be 233mm and the overhang will always be 17.8mm; which is achieved by sliding the base back and forth. When the overhang is at 17.8mm, the pivot to spindle distance is automatically correct (no need to drill a precisely located hole in the TT armboard) and the cartridge, when adjusted true and parallel to the headshell, will be tangent to the grooves at two points; and if the cartridge is standard, one need only add the difference to the 233mm and look up the adjusted overhang (DB provides a chart) and you're in business.
My only gripe is SME's roundabout and imprecise way of checking the overhang -- typically British! However, the design objective of the SME V tonearm was to fashion a headshell/armtube/counterweight-carriage out of a SINGLE casting, in order to provide the most rigid platform ever conceived for mounting a cartridge; along with their use of outrageously expensive ABEC 7 ball race bearings that nobody else uses. So you see, the single hole mounting arrangement is not an arbitrary SME affectation, but works to locate the cartridge in exact relation to the other tonearm dimensions. Setup is really a snap with a standard cartridge andnot much harder with a non-standard one.
Granted, one gives up certain niceties to enjoy the unique attributes of an SME V tonearm. For instance you can't adjust stylus azimuth; but on the other hand, any cartridge worthy of living in an SME V should come with perfectly aligned stylus/cantilever; and if it doesn't? well at those prices, it goes back for an exchange!!
Adjusting the SRA (some call it VTA) can also be frustrating if you're expecting to just 'dial it in' like a Graham or a Tri-Planar. And if your (most likely modern MC) cartridge is too short, you'll need a headshell spacer to keep the back of the armtube from hitting the edge of the record ;-)
My advice to Pureretro: You have one of the finest, most foolproof, durable and easy to set up tonearms in the world. I've owned mine since 1990, and in 2004 sent it to England for its 200,000 mile checkup (they couldn't find anything to adjust!) and to update the internal wiring. That was it! So keep the DB and buy a nice thin metal mm scale so you can check the overhang accurately. (You'll figure it out.) And if your eyesight is shot, just get a great big magnifying glass ;-)
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The SME V has a sliding base in order to provide for proper stylus overhang adjustment without the necessity of slotted headshell mounting holes. The SME V design philosophy is to have a completely rigid tonearm wand (which is also the reason the headshell cannot be rotated for azimuth adjustment.)
Supposedly, the SME V alignment templates provide for obtaining the proper stylus overhang, but I find them inexact (to say the least!) It's much easier to use a small thin metal millimeter scale placed carefully on the spindle with the other end supported on a rubber eraser or some such. Then with the anti-skating OFF, it's easy to set the stylus on the metal scale and rack the tonearm base back and forth to achieve precise stylus overhang right at the spindle.
After that it's relatively easy to use a DB or other protractor to adjust the cartridge parallel to the protractor gridlines at two points. |
Nobes, I understand your point, although I think "several mm" variation may be an exaggeration, especially with today's cartridges.
I'm not familiar with the use of the Mint alignment tool. However, I do know that a DB protractor gives accurate two-point tangency results so long as the stylus overhang is accurately adjusted for the tonearm being used. Small variations in stylus-to-pivot distance are apparently of far less consequence than an accurate (optimum) overhang setting. This is further illustrated by the fact that DB provides/allows a 6mm range of effective arm lengths in each of eight groups of arm lengths to which optimum overhang figures are attached. |
Dan, like I said, the SME alignment templates, though beautifully made, rely on 'by eye' guesstimates, which hardly cut it at that level of refinement; and I'm confident anyone who has ever used them would agree ;-)
The DB alignment protractor is also beautifully crafted and allows for very precise measurements; unfortunately though, DB leaves it up to the individual to figure out how to set the stylus overhang, and does not provide a tool for doing so. Failure to set overhang exactly, and the inability to use a Vernier scale probably account for poor results when they occur, but don't blame the DB. Used properly, I think it's as accurate as anything out there. |
Nandric, in all alignment procedures (except the SME) it's mandatory that a prescribed stylus-to-pivot distance (sometimes called 'Effective Arm Length') be maintained (thus necessitating slotted headshells ;-)
Further, a fixed arm length requires a specific (for that tonearm) spindle to pivot distance, and most tonearms come with an appropriate (though not always well crafted) template. If the one you got is sloppy, or non-existant, it's best to make your own out of a piece of acrylic. Slip one end over the spindle (with the platter removed) and, through a tiny hole in the template drilled the correct distance from the center of the spindle, scribe or draw an arc on the arm board. You can drill the arm mounting hole(s) anywhere along that arc.
Dan asserts that "With an arc-style protractor made for the table/arm combo, there is no need to measure P2S" (I think he meant cartridge/arm combo,) but unfortunately, this is true only if the arm mounting holes have been drilled, and the arm mounted with utmost accuracy, the correct distance from the spindle, per the tonearm manufacturer's specs. In reality, that is REALLY HARD TO DO without proper shop tools, drill press, etc.) If there's any doubt (and even if your TT came with the TA mounted) it's best to field-measure your particular equipment setup and provide the actual P2S dimension to the toolmaker prior to fabrication ;-)
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"P2s and effective length are not dependent on the cartridge used." True. They are instead dependent on the tonearm design and must not be changed. Providing slotted headshell mounting holes therefore allows mounting the cartridge so the exact stylus-to-pivot distance required by the manufacturer can be set, regardless of the cartridge's stylus-to-mounting hole dimension. So with (most) arms you need to be able to adjust the fore/aft position of the cartridge in the headshell. The spindle-to-pivot distance is also specified by the tonearm manufacturer/designer and combined with the specified EAL (effective arm length) provides the correct arm geometry.
Nandric: "BTW the slots are to provide for the distance between the stylus-tip and the fastening bolts because this distance differ by carts. Or so I thought." That is not correct. The slots are to allow one to shift the cartridge fore or aft until the stylus tip is the PROPER DISTANCE FROM THE ARM PIVOT ;-) That distance is called the 'effective arm length', and is pre-determined by the tonearm designer. |
Axel, please! It is NOT another "VTA post" ;-) You do me an injustice!
VTA and SRA are NOT 'loosely' related. In fact, they are not related at all! You really need to edumacate yourself if you want to discuss such subjects.
Yes, the torque of the fingerlift is miniscule compared to the resistance of the vertical bearings. Fingerlift torgue is an issue of course with unipivot tonearms. As for the 'resonance' of the fingerlift? Another 'audio chimera'. It is apparently made of spring steel, yes, but constrained only at one end -- so if it does resonate, be assured it's WELL ABOVE the range of human hearing and at an amplitude only bats could hear! Good God!! |
Dan, the SME slide mount moves the entire tonearm (pivot and all) back and forth, pretty much toward or away from the spindle. Moving this carriage does not change the arm length, which on an SME is 233mm from pivot to the tip of the stylus (of a cartridge with standard stylus-to-mounting hole dimensions.)
Because of the fixed cartridge mounting holes, the arm length of an SME (and pretty much ONLY an SME) wiil increase/decrease by however much more or less the stylus-to-cartridge-mounting-hole dimension deviates from the standard. I.e., if the stylus is forward of the cartridge mounting holes say 2mm more than standard, the the effective length of the SME arm will be 235mm, not 233mm. It's not a disaster though, because you simply have to increase the overhang a tiny amount (according to a chart) and everything goes back into proper relationship.
Personally, I'd advise anyone using an SME IV or V to use cartridges with standard stylus-to-mounting hole dimensions. It makes life easier and still leaves a zillion cartridges to choose from ;-).
Setting up proper SME arm geometry involves two steps:
1,) checking/setting the stylus overhang (using the sliding carriage base), and
2.) adjusting the cartridge horizontally to align with the gridlines of a DB (or other conventional protractor) at the two null points (there's enough play in the mounting holes to allow this adjustment.) And that's it ;-) |
Nandric, Jonathan Carr (who manufactures the very fine Lyra cartridges) and I agree completely, even though I said it somewhat differently. I said: Because of the fixed cartridge mounting holes, the arm length of an SME (and pretty much ONLY an SME) will increase/decrease by however much more or less the stylus-to-cartridge-mounting-hole dimension deviates from the standard. I.e., if the stylus is forward of the cartridge mounting holes say 2mm more than standard, the the effective length of the SME arm will be 235mm, not 233mm. It's not a disaster though, because you simply have to increase the overhang a tiny amount (according to a chart) and everything goes back into proper relationship.
Personally, I'd advise anyone using an SME IV or V to use cartridges with standard stylus-to-mounting hole dimensions. It makes life easier and still leaves a zillion cartridges to choose from ;-). He said: Baerwald alignment even if the cartridge doesn't adhere to 9.52mm (and the effective length therefore changes). Simply recalculate and readjust the overhang (via the SME's sliding base), likewise for the offset angle (the difference in diameter between screwhole diameter and screw diameter should be enough to accommodate the majority of cases). The tonearm geometry will now be a little different from what SME designed for, and you most likely will need to switch to another alignment gauge (not an arc-type). Not as convenient, but the results should sound fine, which is the most important thing. I also mentioned, as Jonathan did, that there is enough play in the SME mounting holes to provide for offset adjustment if necessary. Neither of us even suggested (much less stated) that an SME IV or V arm could not accomodate ANY cartridge, and I don't know how you came to that understanding. As for variations in spindle diameter - well they can't vary too much can they? ;-) It's only important that a template hole fit over the spindle without significant play - an easy thing to fix (if it occurs) with a couple turns of teflon tape. Drilling the armboard so the mounted tonearm winds up the proper distance from the spindle is far more important in my opinion, and not as easy as it seems at first. My "beloved SME V" is the most rigid yet fluid cartridge mounting platform ever concieved. The fixed mounting holes are absolutely necessary for that achievement. In case you were unaware, SME makes a Model V with an adjustable headshell for those willing to trade the utmost performance for a bit more convenience. Neil . |
Axelwhal, believe it or not, there is a small coterie of SME V owners who are quite anal retentive. They're the ones who refuse to use the arm with the finger lift attached, and who remove the bridge across the main bearing. With all audio refinements/improvements/adjustments, proof of concept is always going to be decided by the answer to two questions: "Can you hear a difference?" and "Do you like the Emperor's new clothes?" No one who uses anything more sophisticated than a record changer will argue against careful setup - even those who haven't learned to do it themselves. The implication that certain arms/tools can provide 'tighter' setup tolerances is just baloney as I see it. I've been setting up arms and cartridges for 50 years, and I'm a stikler for precision in all things mechanical. The only changes I've witnessed in all that time vis a vis tonearm setup, are tools (such as Mint and Wally) that make the process easier -- especially for those who don't have a lot of practice and/or skill. What makes me laugh is the notion that one can do a better job using those tools. Maybe faster, but not better. If anyone using a line contact (or micro-ridge) stylus equipped cartridge really wants to experience a revelation in cartridge performance I would refer them to the following thread: http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1140840022&openmine&Nsgarch&4&5&st0 Boy! Do I wish someone would make a tool for doing that!!~ . |
Axel, you clearly did not read my thread on SRA.
"VTA" isn't even a real world entity (or concept or whatever) and is absolutely useless. People who think VTA is real are indeed doomed to "keep on chasing 'sound'" because VTA doesn't exist (unless your cartridge just happens to match the cutterhead in all dimensions and angles -- yeah right!) So just forget about it!
As for SME mods, I just don't believe in guilding the lily (or removing petals from it ;-) The SME arm is all about RIGIDITY and ZERO FRICTION -- both to the max. So I have to assume the bridge is there for rigidity, or else, as Bette Midler would say, "Why botha?!" As for the finger lift, I hardly think the tiny axial torque it creates will affect those huge ABEC horizontal bearings in the slightest.
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Axel, here again is the link: http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1140840022&openmine&Nsgarch&4&5&st0And in any case *SRA* is wrong also, since it should be then called *SCLRA* Stylus-Contact-Line-Rake-Angle, since the 'stylus' is only doing that picking-up via its 'contact-line' touching the groove, yes?
And as it so happens, the angle of the contact-line maybe just as unrelated to that 'clump' of stylus also! Technically you have a point, however, the usual fabrication of line-contact styli (except the Shibata) produces a shape that is symmetrical when seen from the front or the side. Thats why it's so relatively easy (as my photographs show) to determine when the "line of contact" is perpendicular to the record surface. Getting from there to a useful rake angle is a fairly simple calculation, and with some tonearms, a fairly simple procedure (NOT the SME unfortunately ;-( The idea of properly setting the SRA (again, only an important issue with line contact styli) is to have the ridges on each side of the stylus 'lean' forward at the same rake angle as the cutterhead (or did you think cutterheads were positioned straight up and down? Ever try using a chisel that way ;-) Ah the fingerlift again. Well, I don't care if you amplifiy it a million times, you won't hear it ;-) |
Typical cutterhead angle is 1.5 deg. +/- depending on the lathe operator. I confirmed this with Stan Ricker, a well-known mastering engineer and lathe operator (Cardas Test Record.)
The precise angle of the cantilever to the record surface is irrelevant for playback. It can vary from zero deg. (for strain gauge cartridges) to 90 deg. (Decca cartridges) and everything in between.
However, ensuring that a line contact stylus' edges line up with the angled groove undulations is essential, no matter how it's attached to the cantilever, or what the VTA winds up being. Don't worry about those things.
It's nice to be able to adjust SRA on the fly to compensate for different record thicknesses and lathe operator preferences, but 1.4 degrees seems to be a good average if 'on the fly' is not possible (e.g. SME arms.)
If you set up your arm geometry carefully and adjust for close to the correct SRA (or exact SRA if your arm provides) that is at least 90% of the job.
It's then easy enough to check for correct azimuth with a test record, and for VTF by ear. Anti-skating force settings for line contact styli is about 25% that necessary for spherical or elliptical styli because of lower friction and groove drag.
If you'll follow this strategy, you can be confident you are getting the most out of your tonearm and cartridge. |
Well, I like baloney. Especially fried. So I guess that the rather large population of A'goners who have achieved better results using both the Wally and MintLP are just delusional? C'mon Dan. You know that's not what I meant, right? I'm confident, using my "stone age" methods, I can achieve the same precision as someone using a Wally or a Mint at least with my arm. But then, I've had a lot of practice, am very patient, and have a few tricks I've learned over the years ;-) It's not something I do often, so I'm willing to trade a little xtra time for a lot of xtra money. Heck, it makes me crazy just seeing my DB protractor sitting there in the drawer, staring at me! |
