Linear tracking

[stereofanboy]

The recent belt vs DD thread reminded me of something I have often wondered about; linear tracking turntables. Right before cds really took over the market, most of the manufacturers were making linear tracking models. The marketing made them sound like the most obvious thing, but now they are pretty much, if not completely, gone.

Was a fatal flaw discovered with this type of table, or were they abandoned because turntables were considered to be a dying market? What about now?

 

[JohnVF]

The better ones work very well. And there's some high end linear tracking arms that you can still buy (Eminent Technology's air-bearing arm being one off the top of my head). For all of their added complexity, however, in my experience they really don't offer improvement over a great pivot arm, making it a big question-mark as to whether all that added complexity is worth it. One of my tables is linear tracking, a Mitsubishi LT-20. It's a very fine sounding table, and built very well. But I have pivot-arm tables that sound just as good and have a lot less things to go wrong. But when well-implemented, there's nothing wrong with them. I think a lot of the bad-press they get is because a number of cheap turntables used cheap linear tracking arms, and they're lackluster performance tainted the whole idea, because you get a lot of people chiming in with things like they 'crab walk'...moving, then playing, then moving...only really being tangential for a moment before the arm is off, which triggers its movement. I think anybody who has owned one of the better LT tables would disagree that this is a big issue when they're in proper adjustment, and if you press the people insulting them, you almost always find out that they've never actually owned much less used one for any length of time. The "expert by conjecture", which is prevalent in our hobby.

You can often get them pretty cheaply for the sound they deliver. I honestly like my Mitsubishi LT-20 a lot better than my Linn Axis, for example. I thin it sounds better, too. My only issue is that it's a bit sterile in the actual physical nature of the playback. Moving the arm by pushing buttons is just no fun to me. I like to manually cue. But this has nothing to do with the sound.

 

[js1138]

But I have pivot-arm tables that sound just as good and have a lot less things to go wrong.

Says it all.

 

[Arkay]

That "expert by conjecture" comment is absolutely correct. Competitors start specious arguments or rumors that any engineer or scientist (in a relevant field) can tell you are borderline (or completely) ridiculous, or taken way out of context, or extremely exaggerated, and those rumors somehow take on an undying life of their own, in the hands of people who have no relevant experience. Linear tonearms "crabwalk" (but even the cheap ones that do, are still WAY closer to a correct tangent, more than 95 percent of the time, compared to a pivot-arm). Direct drive motors "cog" (but only the earlier models, and only when you remove the platter, which is like trying to run a belt-drive motor without half the spindle.) Such distortions, half-truths and outright lies live on as widespread misconceptions.

There were --and are-- a number of excellent linear trackers made.

I and at least one other AKer (that I know of) own Pioneer PL-L1 linear trackers. VERY NICE turntables, by any measure.

Goldmund has made some great-sounding linear trackers, although theirs are not always easy to keep in good working condition.

Among new turntables, the Clearaudio statement and some others are also linear-tracking, and it's hard to fault their sound unless you are being ridiculously golden-ears picky.

It is simpler and cheaper to make a belt-drive pivot-arm TT than a DD linear tracker. Companies that tried to make the latter types at a modest price point inevitably made too many compromises, which gave the designs a bad name. But the companies that did things right made some great TTs and arms. Just not cheap ones. [The ultimate example is probably the Rockport Sirius III, a DD linear tracker that many believe is still the best TT ever made.]

 

[koseltri]

Those of us that have good ones like them for various reasons. The good ones are equal in SQ to comparable pivot tables. I like the auto function--I rarely have time to sit and cue (and more importantly, pick up) a tonearm. I can do other things at the same time and not worry. I like their complexity, their engineering is admirable. I like the idea of keeping them maintained (there really isn't much to do, and I haven't had one fail on me, tho' I picked up one that needs repair, which it can be). I don't have the money to tinker with cars, so it keeps me satisfied. And the :nerd: in me just thinks they're cool. And no protractor(s) to muck around with.

 

[derekva]

Those of us that have good ones like them for various reasons. The good ones are equal in SQ to comparable pivot tables. I like the auto function--I rarely have time to sit and cue (and more importantly, pick up) a tonearm. I can do other things at the same time and not worry. I like their complexity, their engineering is admirable. I like the idea of keeping them maintained (there really isn't much to do, and I haven't had one fail on me, tho' I picked up one that needs repair, which it can be). I don't have the money to tinker with cars, so it keeps me satisfied. And the :nerd: in me just thinks they're cool. And no protractor(s) to muck around with.

They also work very well for systems for kids, or in the case of the SL-7 that Scott generously sold me, for systems with limited space (e.g. trying to retro-fit a Maggie Imperial console).

The SL-7 is a very good linear tracking table in a very small form factor.

-D

 

[PickyEars81]

I have one. It offers nice automated functionality, at the cost of maintaining additional belts and motors to control the automated functions. Mine is kind of low fi; only accepts p mounts. I like the Clearaudio linear trackers :drool:

 

[Zygmo]

I have one of those cheap ones....a Zenith, that nobody seems to remember (including belt supliers) After replacing the belts, it works fine, sounds ok. But talk about complexity!! And slow. But, it is compact. I use it as a spare in my computer room.

But, give me a pivoting tone arm anytime! :thmbsp:

 

[JohnVF]

They're easy to set up, too. I love how easy it is to set up my LT-20.

 

[Nat]

Okay, Okay -- hate to break up the lovefest, but those 'experts by conjecture' are only around because of the claim that linear arms have zero error. Obviously they do not, since then there would be no way for the arm to know to move as the groove advances inexorably inward. Sure it's true that a properly operating linear arm has less error than a properly operating pivoted arm over most of the record, but 'no error' is as true as 'perfect sound forever', and its annoying to hear the claim made, because its false, but more important, it's misleading.
With all aspects of vinyl reproduction, implementation is everything, and balancing conflicting goods is the essence of optimizing reproduction. And a linear arm is inevitably more complex than a pivoted arm (and though good bearings are expensive and pivoted arms have to have bearings, whereas linear arms do not necessarily have them). Therefore at a given price point, the linear arm is likely to be less well made than a pivoted arm.
And holding the cartridge perfectly tangential to the groove is only one thing that the arm does. All arms have resonances, and though the shorter linear arm may have an easier time being rigid, generally linear arms have much more different horizontal and vertical masses than pivoted arms, and this has to be handled properly.
And as John VF mentions, differences in how you interact with the arm have a big effect on how much you enjoy using the arm.
By the way -- no way is setting up the LT 20 easy, unless you have the supremely weird (therefore cool) specific protrator for it -- it is a plastic plate that fits over the spindle and, when the platter is turning, is forced against some other part of the table, with a grid that is a radius from the spindle and parallel to the arm travel. (Only when the plater is turning can you lower the arm to check alignment.)
Otherwise you have to measure the (rubber) edge of the headshell bayonet to the stylus tip, and, as far as I know, ignore the 49mm handwritten markings on the Vinyl Engine owner manual and measure 50mm (if you remove the rubber washer then it is 49mm). And you have to ignore suggestions you rest the stylus tip on the top of the spindle: First, you can't, since the spindle of the LT 20 is oddly tall, and, Second, that will give the wrong alignment since the arm travels an arc, not a straight path down to the record, and Third, the arm can't go that far.
Do I sound annoyed? That's another problem of linear arms -- all sorts of advice from people who assume that all perfect arms are exactly alike. (Of course, that's actually more or less true with those imperfect pivoted arms -- geometry is geometry, and you don't have the electrical interlocks that you have with linear arms. But the world of imperfect pivoted arms is just as imperfect -- there are the ranters who don't realize that there are different alignments, not just Baerwald, but also Lofgren (and Baerwald may have plagarized) and Stevenson -- you get those who claim that Technics, or even bolder, all japanese turntable makers who made TP4 arms are incompetent idiots.)
What a veil of tears we live in.

 

[22frank]

Linear Tracking DIY Rabco SL-8E

I got my Thorens TD 125 MK II years ago (1974) it came without a tonearm... I tried a Shure SME with Ortofon cartridge.. It worked fine, but the antiskating force correction seemed odd. All swing arms have this problem. The Rabco SL-8E doesnot have that problem. Like others state to play the record it must crab walk. Two small gold plated wires make and break contact. They must be cleaned sometimes and I'm sure they like smoke free rooms. The arm is shorter and moves up and down with the record better, in my opinon, then a long swing arm. At the time with the same cartridge the rabco sounded beter to me. It is a rube goldberg sort of operating thing. I have had no problems with it for 35 years. It is a DIY thing, I have to keep it running myself and I like that.. The hardest part was a plexiglass window on the dust cover that had to be made to get the cover to close. Love the vinyl sound over the CD DVD stuff!!

 

[Karma16]

HI Nat,
Perhaps you will reconsider your post when discussing air bearing arms. Here the tracking error truly is zero. I have two Eminent Technology ET2.5 air bearing linear tracking arms. No off tangent error is needed to maintain zero. I can tell you that they are the best I have experienced and I have experienced many fine, high end tone arms.

The problem with forums are the generalizations that evolve into truth. An example is when people discuss turntables they generally never consider the tone arm which usually integrated. In such a case, both the arm and table must be considered. In my case, my three turntables all have arms that were designed and built by another company and mounted by me. Thus, I truly can discuss the arm or turntable without consideration of the other. This is not true of integrated units.

Of course, they must work well together. That's a given.

Sparky

 

[Nat]

Karma16 -- yours is a point often made, but I'm not persuaded. I recognize that air bearing arms don't pivot in the horizontal point, and that their friction is very low, but the groove will go where it wills, and the only way the arm can move is if the groove pushes the stylus, and the stylus is attached to a suspension, which is flexible, and that compliance is acting into a fairly large mass, so the groove is going to force the stylus out of tangency first to get it going, and then to stop it from overshooting.
YES -- this error is small, and the debate is like that I had recently with a student who was (mis)quoting a calculus teacher, arguing that .999 repeating is identical with 1. Granted the difference may be functionally unimportant, but the two numbers are different, and if they aren't, then no number is distinct from another.
And saying that a linear arm is functionally error free is an importantly different thing than saying it is error free, because it brings function into consideration -- and in a complex mechanism, function is crucially important. In the real world, dust, dried grease, lack of perfect horizontality, misalignment and so on always matter.

 

[Karma16]

HI Nat,
But an air bearing is friction free. No grease, no horizintal pivot. The major error (very small) is the pitch of the groove which is variable due to variable pitch cutters. This acts on the mass of the arm but the force is very small. Friction and tracking error are non factors. Of course this is also true for skating force.

Actually, I'm not going to argue further. I suggest that you not argue either. You are just being difficult obviously with no first hand experience. Just go listen to an air bearing arm and make up your own mind. But watch out, you may buy one. You should for so many reasons.

Sparky

 

[guest116]

I got my Thorens TD 125 MK II years ago (1974) it came without a tonearm... I tried a Shure SME with Ortofon cartridge.. It worked fine, but the antiskating force correction seemed odd. All swing arms have this problem. The Rabco SL-8E doesnot have that problem. Like others state to play the record it must crab walk. Two small gold plated wires make and break contact. They must be cleaned sometimes and I'm sure they like smoke free rooms. The arm is shorter and moves up and down with the record better, in my opinon, then a long swing arm. At the time with the same cartridge the rabco sounded beter to me. It is a rube goldberg sort of operating thing. I have had no problems with it for 35 years. It is a DIY thing, I have to keep it running myself and I like that.. The hardest part was a plexiglass window on the dust cover that had to be made to get the cover to close. Love the vinyl sound over the CD DVD stuff!!

I use nothing but LT arms and won't ever go back to a pivot. The SL-8E was the first LT arm I used and I love it still. Currently using the Trans-Fi Terminator T3Pro air bearing arm.
The Rabco's mechanism is more complex than a pivoting arm, but it's reliable. Set up is far easier since the distance from the spindle to the arm base can be anything from 16.5 to 20.5 mm. Maximum tracking error is only .16 degree, less than the tracking error inherent in the standard-length pivoting arm. There are no skating forces to deal with.
The air bearing Terminator is far simpler than the Rabco and outperforms it, but I'll never sell my SL-8E. One of these days, I'll have another turntable to mount it on.

 

[SA-708]

... the groove will go where it wills, and the only way the arm can move is if the groove pushes the stylus....

Doesn't that also apply to pivot arms?

 

[Rey1]

if you press the people insulting them, you almost always find out that they've never actually owned much less used one for any length of time. The "expert by conjecture", which is prevalent in our hobby.

I agree completely! I own a PS-SL7 that I love. It sounds great, is well built and seems reliable. Technics also had some nice ones. That being said, they are no better than a good pivot arm table.

 

[Nat]

Karma16: we've disagreed about this before, I think. My comment about grease was obviously with regard to mechanically driven arms -- I was commenting about about the real world problems of all arms, and giving illustrative examples.
Not sure why you are so certain I have no first hand experience. It is true that experience is often a good corrective to theory, but that cuts both ways -- I have experience of good sounding linear arms, but I also have experience of crabwalking, and even of the two at the same time, which is why I think that other aspects of arm performance than tracking error matter more.

 

[Aerobat]

Karma16: we've disagreed about this before, I think. My comment about grease was obviously with regard to mechanically driven arms -- I was commenting about about the real world problems of all arms, and giving illustrative examples.
Not sure why you are so certain I have no first hand experience. It is true that experience is often a good corrective to theory, but that cuts both ways -- I have experience of good sounding linear arms, but I also have experience of crabwalking, and even of the two at the same time, which is why I think that other aspects of arm performance than tracking error matter more.

I don't think anyone ever said linear arms have zero error, yet this is what you seem to be arguing against. Linear arms have less error, and no skating force.

 

[Nat]

If you go back to the beginning of this thread, I was responding to the 'expert by conjecture' comment, the implication of which was that if you suggest that linear arms are as problematic as pivoted arms , you must not actually have sufficient experience of linear arms and therefore don't know what you are talking about. Very frequently - not always -- this claim is accompanied by the claim that linear arms have no error, as if this is self evident and incontrovertible.
The point I have argued is that in the real world, you have to deal with all the practical ills of misalignment, things being out of level, things working improperly, resonances, masses, blah blah blah. These things may actually be more important than the type of arm, even in situations where the arms are working perfectly, and the complexity of linear arms is a significant hazard to whatever perfections are claimed for them.
I know many people don't agree.