[neobop]

Because of the confusion on the universal template thread, I thought it would be a good idea to offer an explanation. I was hoping that someone else would initiate this, and offer alternate methods for aligning a cartridge, but I guess the thread was withdrawn.

Just like in geometry, there are sometimes different ways to solve a problem. It depends on what is known, and what you're looking for. In this case the problem involves circles mostly. The arc of the tonearm is part of a  circumference of a circle, with the length of the arm being the radius. The grooves of the record can be seen as a series of concentric circles with the spindle as the center. There is a line coming off the end of the arm. This line is the angle of the cartridge.

What is the objective here? We are looking set the line coming off the arm (cartridge) at a place along the arm, so that it is tangent to the groove in 2 places along the arm arc. So, in most cases the length of the arm can be varied somewhat. If you move the cartridge forward or backward, you're changing the arc of the arm.

In that other thread, I said that you can align a cartridge with most arms even if the spindle to arm mount is off slightly. With a 2 point protractor or one of the pivot based (Dennesen/Geodisc), you can. If you put the protractor on the platter and get tangency at those points, you have achieved that alignment. What you might have altered slightly, is offset angle and effective length.

What are the implications?
It depends on the arm, really. It also depends on how much these parameters are changed. Chances are, if the mounting distance is only off by a couple mm, not much if any audible change will occur. Any time you try a different alignment, you'll be making these same type of changes, assuming you don't re-mount your arm. Often, when changing alignment, you have to angle the cartridge slightly to get it squared up on the grid. When moving the cart further forward, as in going from Stevenson to Baerwald, the part closest to the spindle will usually have to go further back, increasing the offset angle. This does have implications. Once again, it depends on the arm, and whether or not the new alignment, with slightly more anti-skate required, sounds better than it did previously.

Mass market Japanese arms, back in the heyday, used mostly Stevenson alignment, or close to it. It was common to try a Baerwald on these, and everybody seemed to like it better. Sometimes the cart would have a much greater offset angle and look funny. It would usually sound better to most, if your cart would physically allow the change. Dimensions differ. Much of this depends on the arm length. IMO Stevenson can sound pretty good, but on longer arms only. The end of record sounds great, but the beginning can sound a little rough.

There are alternate alignments that have no name. If you don't have room to get Baerwald, you can get one of those straight line calibrated grids. Mark off your preferred alignments, and get as close as you can. Stevenson has nulls at 60.325 and 117.42 and Baerwald at 66 and 120.89. So if you get it to square at 64 and 119, it's a good alignment for that cartridge, if you like it.

I'm using Baerwald as an example, because it is the most popular. 98% of aftermarket devices are Baerwald. However, Loefgren B is gaining in popularity. It definitely has advantages, but most arms can not achieve it. That's where an alternate geometric approach comes in.
neo

[hesson11]

Well done, indeed, neobop. That's one of the most lucid explanations I've read, and I've read a lot of them. Of  course, a comprehensive explanation would require a hell of a lot more words, but your post could serve as a great introduction to anyone setting out on the often daunting path to vinyl competence.

-Bob

[neobop]

Thanks Bob.

I ended the initial post alluding to an alternate way to approach the problem of attaining the desired null points. Just like in geometry, there are often different ways a problem can be solved, depending on the information you're given. The use of an arc or TT/arm specific protractor is dependent on 1 constant. That is mounting distance or the distance from center spindle to the center of the arm mounting hole. If that is set exactly at specified distance, then an arc can be computed that will give you a grid set exactly on the alignment desired. Usually these arc protractors have a 2nd grid to check mounting distance. The 2nd grid is not necessary for the alignment if the arm is set correctly. Using Rega as an example, if you have a Rega table, then it's a pretty safe bet that you arm is set exactly at 222mm. If you wanted to change the Rega factory alignment, which is very close to Stevenson, to Baerwald, then a Rega/Baerwald arc protractor makes it relatively easy.

If your arm is not set exactly at factory specified mounting distance, but you can measure or figure out what that distance is, exactly, then you could use a custom arc protractor based on that mounting distance. Whether or not you can achieve a particular alignment, with a particular cartridge, is another question.

As a disclaimer, I just want to say that there are some arms that are inappropriate for this kind of geometry manipulation. I have a unipivot that specifies every set-up parameter and any deviation will degrade performance. Even the angle of the arm, between the rest position and a line to the spindle from the mounting hole, is specified (57 degrees). The mounting hole is not coincident with the pivot. But this is the exception rather than the rule. With most arms you'll not have this consideration.

Now there are computer programs.....
neo

[steveblezy]

Indeed there are many ways to solve a problem. As I mentioned for myself in the previous thread, the most convient method for me was with the  Feickert protractor due to the way it works. I have been using a Rega based arm and had it at 222mm but not with the recommended Stevenson nulls. I used both  Baerwald and Lofgren. In both cases I always managed to hit their null points. In both cases it was possible because I first set the required effective length as the first step.  They both sounded good. Recently, The Feickert people have added something to your pdf instruction for Rega owners when using their protractor which was to have a spindle-pivot of 218/219mm instead of 222mm. I tried it, first setting my overhang and I hit both null points. So, regarding alternatives, 1 arm, two different spindle-pivots, 2 different nulls. They all sound great and are each achievable. While I have never used the Dennesen/Geodisc, I expect that you can probable achieve something similar, but, I have never tried them so I am only guessing.

No matter what method or tool you use, if you can set your effective length correctly and if the headshell allows the required movement, I would expect that you can use a variety of different spindle-pivot distances and achieve good results.

Steve

[Wayner]

Unfortunately, there are a few missing pieces to the alignment puzzle. If you examine each of the null points defined by Stevenson, Baerwald or Lofgren (Loefgren), they all have shifted the distortion curve either towards the center, or towards the beginning of the LP. Every one of the curves is a trade-off, shifting the null points changes this. Some tonearm lenghts have only 1 null point in the effective playing area, and an example of that is the Technics SL-1200 and all of the series designs that use the 215mm P to S spacing and the supplied Technics overhang adjustment tool. Setting the Technics with this tool graphs out very poor with an extreme amount of distortion at the beginning of the record. If we look at the specifications for the Technics arm, we discover that the effective length is 230mm, meaning that the included stlyus gauge puts the overhang at 15mm. Why did Technics engineers decide on this overhang? I have no idea. If we change the overhange to 18.282mm we can achive the Lofgren B curve (null points at 70.285 and 116.604) and reduce overall average distortion and reduce lead-in distortion, making the Technics a better performer.

To determine the required overhang, the vinylengine website has a small program called TemplateGen. It asks for the pivot to stylus distance of your turntable, you select if you want Lofgren A (Bearwald) or Lofgren B curves (also select IEC) and it will give you the perfect overhang for that S to P distance.

I have drafted these results on CAD and they are perfectly correct. You may then print out the curve and point graph, but much care and repeat printing must be done to get the scale correct.

I will say that the "industy" is confusing the consumers on this whole topic, because most people don't understand geometry and think there is some magic pill to the whole topic. It's just all plain geometry.

Now, I'm not going to argue with neobop which guy has the best or most popular set of null points, but I will say that which ever one you pick (and I also do not suggest Stevenson's), that you get all the numbers correct. By the way, if you want to set the Technics to Bearwald's curve, then use 17.817 (null points at 65.998 and 120.891)

In either curve, the overhang has been changed from 15 to 17.817, or 18.282, which is a significant amount. This method can be used with almost any table made and will improve the over all sound, along with properly set SRA and anti-skate.

I should point out that when the stylus is set to a null point set, that is what sets the offset angle. Most alignment tools will have grid work that you align your front end of the cartridge to at both points. If it does not align at both points, something is wrong and the overhang is incorrect.

Wayner

[neobop]

Hi Steve,
Denesen/Geodisc are alignment specific. They are Loefgren A/Baerwald. Also, if you can't sight your pivot intersection from above (Dennesen) or from the spindle side (Geodisc), they are useless. But if you can sight the pivots, they are an easy to use 1 grid alignment, just like an arc protractor, only mounting distance does not have to be perfect. 

It's unusual that you are able to get all 3 standard alignments with your Rega based arm. Due to cartridge mounting and headshell limitations, often all 3 is not doable. Loefgren B, with nulls out to 70.29 and 116.6 often requires reducing the eff length somewhat. I guess this is the reason for the 118/119 alternate mounting distance.

Changing alignments requires changing overhang or changing mounting distance or both. Normally, it's overhang that is changed. Overhang is simply that part of the eff length that goes past the spindle. To get the cart to null at different points, requires a different eff length/pivot to stylus distance. That is what you're changing when you move your cart further forward or back.
neo

EDIT: Wayner, no argument here. I wasn't disputing a specific alignment, only the viability of using an estimated eff length for certain alignment methods. Peace.

[JoshK]

I have been reading up on the topic of alignments for all of 2 days.  I had never seen the names Bearwald, Lofgren (except for Nils), or Denesen, et al until that other thread.

However, my simplistic understanding of the problem is that vinyl is cut with a linear tracking like cutter, so the cutting head moves horizontally along a line.  Most conventional tonearms pivot from a single point therefore the stylus follows an arc.

The arc must approximate the line the best it can.  The deviation of the arc from the line is called the tracking error.  This is much like the opposite problem as calculus where a bunch of small lines approximates a curve. 

What Baerwald demonstrated was that for a given arc curvature that the tracking error could be minimized with a certain alignment with "null" points at a certain two points.  This is really analytic geometry, a fairly classic calculus problem. 

That is really my understanding of the problem.  He chose to minimize the tracking error of the arc from the line, this ensures minimal distortion for the entirety of playback.  I am assuming alternative alignments make different compromises or are better suited for a different arc curvature (different arm length).  Is that correct?

Tangential comment:
I see tons of obscenely expensive hi-end convential pivot tonearms on the market and then wonder why.  Why not just go linear-tracking tonearm?  I can see the reason for convential pivot for economical tonearms, but why hi-end? 

[TheChairGuy]

That is really my understanding of the problem.  He chose to minimize the tracking error of the arc from the line, this ensures minimal distortion for the entirety of playback.  I am assuming alternative alignments make different compromises or are better suited for a different arc curvature (different arm length).  Is that correct?

Tangential comment:
I see tons of obscenely expensive hi-end convential pivot tonearms on the market and then wonder why.  Why not just go linear-tracking tonearm?  I can see the reason for convential pivot for economical tonearms, but why hi-end?

Linear-trackers don't perform particularly well with warps.  So their 'laboratory' advantage is often muted by real world conditions.  Vacuum hold downs and outer and inner ring weights seem almost essential with their use.

Longer than-bog-std-9" -arms are a different matter.  That makes sense in almost very way to improve tracing distortion if that option is available. Good ones exist today for less than the cost of many obscene priced 9" arms....and will out-track nearly any 9" arm in both theory and reality as they will coast over warps better, too, as they have higher tracing limits across the 12" arc. 

An further added advantage to longer arms (be they 10", 10.5" or even 12") is that the improvement in tracking is so great that they are less tweeky to set up perfectly...they have higher abilities to begin, so you don't have to tweek their geometries to get out the best efforts. 

Longer tonearms are like Shaquille O'Neill (in his prime)...he didn't have to work as hard as others around him as he had inherent advantages built in (tall, HUGE, fast for his size, etc).  Even in games he coasted, he was still often the most dominating player on the court 

John

[BobM]

Tangential comment:
I see tons of obscenely expensive hi-end convential pivot tonearms on the market and then wonder why.  Why not just go linear-tracking tonearm?  I can see the reason for convential pivot for economical tonearms, but why hi-end?

Pivoted arms just need to move around that pivot. Linear arms need to slide. When they slide they need to stay centered in the groove, which may or may not be cut perfectly, so they can bump one way or the other (think of a non-centered hole in a record) causing their own distortion. Neither is a perfect solution and both on an imperfect medium. But pivoted arms are just easier to manufacturer, although they may be harder to align and you can never get it perfect.

You've got to love vinyl to get it right and maximize its virtues. It is not for anti-tweakers. In fact, half the fun may be just discussing all its inhereht flaws and intricate setup necessities. Flog me, I'm a vinyl lover!

[Wayner]

I have been reading up on the topic of alignments for all of 2 days.  I had never seen the names Bearwald, Lofgren (except for Nils), or Denesen, et al until that other thread.

However, my simplistic understanding of the problem is that vinyl is cut with a linear tracking like cutter, so the cutting head moves horizontally along a line.  Most conventional tonearms pivot from a single point therefore the stylus follows an arc.

The arc must approximate the line the best it can.  The deviation of the arc from the line is called the tracking error.  This is much like the opposite problem as calculus where a bunch of small lines approximates a curve. 

What Baerwald demonstrated was that for a given arc curvature that the tracking error could be minimized with a certain alignment with "null" points at a certain two points.  This is really analytic geometry, a fairly classic calculus problem. 

That is really my understanding of the problem.  He chose to minimize the tracking error of the arc from the line, this ensures minimal distortion for the entirety of playback.  I am assuming alternative alignments make different compromises or are better suited for a different arc curvature (different arm length).  Is that correct?

Tangential comment:
I see tons of obscenely expensive hi-end convential pivot tonearms on the market and then wonder why.  Why not just go linear-tracking tonearm?  I can see the reason for convential pivot for economical tonearms, but why hi-end?

That is pretty much it in a nut shell, however, other math geeks, found other null points that are "better", that is where Lofgren came in. Actually the story I heard was that Lofgren was the original creator of the "A" curve and Baerwald admonished on it a bit, but the numbers (and null points are the same.

I think the good news is that everyone is starting to understand the relationships between S to P, overhang and offset angle. They all play a dance with each other. When one changes (as neobop as said) it's usually the overhang, because most tables and arms are at a fixed point, so the only 2 other influences to play with are overhang, and then it's married to offset angle.

Enjoythemusic.com has a nice Excel program, that actuall starts out with Baerwalds "perfect arm" numbers. I think he is the only one that ever came out with the perfect design numbers, as I have never seen Lofgren nail down anything. It's probably no big deal as the distortion curves are so damn close anyway.

I found it actually amazing myself when I discovered that many different S to P lengths can actually end up with the same null points. This blew my mind for awhile. But then I realized that the record is round and when we lengthen the arm, overhang shrinks as well as offset angle. I've been thinking about this shit seriously for about 4 years, almost driving me nuts, but then one day, the light came on.

The phasing distortions still elude me, way too  much math and way over my head. I concede.

The interesting thing to think about is with either Bearwald's or Lofren's null points, these are the only two spots on the entire record side that the timing of the left and right channels are in synchronization. Did that blow you away? If at any other point on the record, our stylus is not perpendicular to the record grooves, one of the channels is lagging in time. It is a very small length of time, but nonetheless, lags. I think this is where some of the weird phase-shifting comes from that some people say they can hear. I don't think I can, and I'm not going to worry about it.

The next big question I have is why didn't the industy standardize some things? Why isn't the a measurement standard for the distance between stylus and mounting holes? If there is, I've never seen it. They standardized the distance between the mounting holes at .500", but that is about it. The other thing that bothers me is why the industry didn't standardize the SRA. If the cartridge is recommended to trak at 1.5 grams, then the SRA should be at 92 degrees at that VTF. Then all we poor consumers would have to do is set the arm parallel to the record surface and be done with. But, no, we have to get USB microscopes and other kinds of viewing devices to see if we can see the fricken stylus, then to try and even figure out what lead-in angle it is.

This hobbie can be very frustrating. I do feel for the newbies. I've been spinning vinyl for about 45 years and I still have lots of questions, questions I not sure too many can answer.

As we go on..........

Wayner 

[neobop]

As I understand it, both Baerwald (Loefgren A) and Loefgren B, were first described by Loefgren. Some people object to the alignment being called Baerwald. AFAIK Wayner is right about the distortion numbers etc being refined by Baerwald. Yrs ago everyone referred to the alignment as Baerwald.

The objectives of the alignments are slightly different. Loefgren A is designed to equalize distortion throughout the entire record. Beginning, middle, and end are the same, is the goal. Loefgren B is trying to minimize distortion completely. If you notice the nulls of Loefgren B are closer to the middle where distortion is greatest.

Stevenson said that distortion and tracking challenges are greater at the inner grooves because of the smaller circles (grooves). So the Stevenson alignment has the inner null set at the standard lead-out groove distance, 60.325mm. Stevenson does perform best at the inner grooves, but at the expense of the beginning.
neo

[neobop]

Concerning arm length:
It's rather obvious that increasing arm length will minimize tracking angle error. There are other benefits as well that John talked about in his post. A longer arm will tend to minimize audibility of warps (warp wow), and SRA variations associated with less than flat records.

If you look at the cartridge/arm/record from the side, while playing a record, you can see this as a big triangle or combination of triangles. The needle is one end of 2 sides of the triangle. The plane of the record is one side. If you draw a theoretical line from the needle to the arm pivots, the arm tube is another side. Drop down a straight line from the pivots to the plane of the record, and you have a right triangle. I think you can see that this is a simplification, but the principals will hold true for most record players. I think you can also see that if you increase length of the hypotenuse (arm length) of this triangle, the behavior described above, will occur. The longer the hypotenuse, the less change will occur at the angle between the arm tube and the straight line dropped down to the record plane.

The down side of a long arm is that arm mass tends to go way up and MOI (moment of inertia) gets degraded.
neo

[TheChairGuy]

The down side of a long arm is that arm mass tends to go way up and MOI (moment of inertia) gets degraded.
neo

Yeah, I have also heard that rigidity suffers as the arm increases in length, too, degrading performance in ways....while tracking is simultaneously benefits. 

I think I've heard this in practice, too

The Ortofon X5-MC is a fantastic sounding cartridge in many ways....it's amazingly clear and I find the midrange and treble to be great to listen to (smoother and almost as lifelike as my vaunted Grado's...and that's just a great thing).  It's eerily quiet and has hair-raising imaging, too, that is a treat. But, it has the most tepid/light bass of any cartridge I have ever owned and have read others mentioning this is passing about it, too.

I don't know the reasons for it - but, it's bass output really is paltry.  So a great cartridge falls to mid-pack for me because of this failing.

Playing it in the 10 or 10.5" arms I have points out this failing.  But, playing in a 9" arm (various) seems to disguise this failing a bit more so I can bear listening to it without taking note of the bass lightness.  It sounds great in my JVC QL-F6 (9") and painful in my JVC QL-Y66F (10") and VPI Classic (10.5")

There are differences heard in all my other cartridges with a variety of arms, but none so transformative as the Ortofon X5-MC in respect to bass...and my overall enjoyment of it.  It simply doesn't sound right at all on the longer arms (and with a stupid, fatty, overly heavy cantilever that Ortofon uses, you'd think it would benefit most of all from the better tracking longer arms)

All the other cartridges are in one way or another, sound better in the longer arms where reduced 'crunchiness' is clearly heard on piano, in particular.  The Grado's, with prodigious bass, sound MUCH better on the longer arms...I suspect bass output is reduced somehow, while tracking (not the strongest suit of Grado's) rises...making for a match made in heaven with the longer arms.

I don't have any scientific measurements for any of this...but the steps have been repeated enough times now that I hear the same things repeatedly in each arm.

Anyhow, food for thought.

John

[Jeff K]

I believe Technics arms have two null points. Albeit, the second null is closer to the spindle that the other popular alignments.


http://www.vinylengine.com/twisting-your-cartridge-headshell.shtml

[Wayner]

I believe Technics arms have two null points. Albeit, the second null is closer to the spindle that the other popular alignments.


http://www.vinylengine.com/twisting-your-cartridge-headshell.shtml

Yes, it does, but it's in the label area and therefore, not a useful null point.

Wayner

[Jeff K]

Yes, it does, but it's in the label area and therefore, not a useful null point.

My labels' edges are all at about 50 mm from center. The Technics nulls at about 58 mm and Stevenson is 60 mm. Granted, it is 2 mm into the run-out area and doesn't make much sense.

[Wayner]

Yes, on my Excel calculator, inner null is 58.8mm and outer is 113.5 with a .536% average tracking distortion, going up to .752% in between the null points. This is just plain bad, and easily fixed with the new Lofgren numbers. The Technics is still a "best buy" in my books 'cause they got lot's of other things really right. I still recommend this table to many people, budget or otherwise. Just change the overhang and offset angle.

Wayner

[neobop]

Earlier in this thread we discussed arm length and some of the advantages and disadvantages. I said that one of the disadvantages is a greater (worse) MOI. The moment of inertia of a rotating object describes how difficult it is for that object to change its angular motion around the axis. MOI can also pertain to non rotating objects. Here's a better explanation than I can give. If you just read the description, you'll understand.
http://en.wikipedia.org/wiki/Moment_of_inertia

So, I think you can see that a longer arm has a worse MOI, as a function of that distance. There is a greater time lag between the stylus and pivots. The motions of the stylus are not just 2 dimensional, horizontal and vertical, they are 3 dimensional. Grooves are cut at 45 degrees. I have read that this is referred to as the sphere of tracking. Anyway, I don't think it's too hard to visualize that a longer arm will be slower to respond to the motions of the cartridge.

Some things that will improve the MOI for any pivoting arm are an underslung counterweight (assuming the weight is above the plane of the record) and having the counterweight as close to the pivots as possible. If your counterweight is far from the pivots, you could try adding a weight to the bottom of the counterweight and re-balancing. The improvement is most notable on warped records.

IMO the best sounding arms tend to be between 9 1/4" and 10 1/2". This is long enough to reduce tracking angle error without the added mass, MOI of a longer (12") arm. Like most generalizations, this is not necessarily true.

neo

[Letitroll98]

Hi Neo,

Having never owned an arm of extended length, e.g. 12" or even the 10.5" of the newer VPI arms, I couldn't comment directly on their sound.  But as I understand it you could improve the effects of higher MOI with better quality arm bearings and stiffer materials, as well as lower MOI by using lighter materials.  So you would have to take it away from a direct comparison of just arm X with an extended length by designing a different, and likely much more expensive arm, but you could get the benefits of lower tracing errors.  I leave it to your expertise if you have come across any that have achieved this paradigm. 

Regarding alignment strategies, one thing hasn't been mentioned, choosing a different inner groove point.  If you move out from the typical 60-63mm inner groove and use 70-75mm, you can dramatically lower distortion across the record.  Most modern records don't go much further inwards of 75mm anyway.  The downside is if you do have many records that go deep into the inner portion and use the 60-63mm space, distortion rises dramatically.

Thanks for listening to my first AC post.   

[TheChairGuy]

Thanks for listening to my first AC post.

Good to have you here, too, Letitroll

IMO the best sounding arms tend to be between 9 1/4" and 10 1/2". This is long enough to reduce tracking angle error without the added mass, MOI of a longer (12") arm. Like most generalizations, this is not necessarily true.

Harry over at VPI has always said the sweet spot in his tonearm choices are the 10 and 10.5" arms. 

I have both a table with 10" arm (JVC QL-Y66F) and 10.5" arm (VPI Classic) and the reduction of 'crunch' (tracking distortion) that I hear especially in piano pieces in noted next to 9" arms on other tables I own or have owned.

I haven't had a 12" to compare further.

Another nice thing about the longer arms as they naturally track better...you don't have to quite put in the gnats hair effort in dialing in their geometry.  In fact, I think the newest Well Tempered 10.5" arm has fixed mounts for cartridge...allowing no adjustment of overhang for various cartridges (as the differences are truly minimal because of the 10.5" arm length)

John