[Wayner]

I have enjoyed reading the article on "Arc Angels"  in the June 2010 Stereophile. As someone who has studied this geometry for some  time, it is very interesting to find the relationships between spindle to  tonearm center, overhang and offset angel. I have included a list of 5 tonearms  that have a spindle to tonearm pivot distance from 200mm to 220mm. It's  interesting to find (and as it should be) as the arm gets longer, the overhang  decreases as does the offset angle, if one is to maintain null point positions.  For my illustration, I used the null positions favored by Loefgren B curve that  has the inner null radii at 70.285 and the outer null radii at  116.604.
   
SPINDLE TO TONE ARM PIVOT    OVERHANG    STYLUS TO  TONEARM PIVOT    OFFSET ANGLE

200                                                  19.535                        219.535                                 25.192                           

205                                                  19.099                        224.099                                 24.644

210                                                  18.682                        228.682                                 24.118

215                                                  18.282                        233.282                                 23.613

220                                                  17.898                        237.898                                 23.128   

Of course, if we continue to make the arm longer,  the overhang and offset angle will start to approach zero, but then, the tonearm  pivot would have to located over at the neighbors, ha.   I also included some CAD drawn graphics to better  illustrate this.   
200mm

 
205mm

 
210mm

 
215mm

 
220mm

Wayner
 

[jtwrace]

I've been reading about the Feickert Adjust +.  It's interesting...

http://www.adjustplus.de/index.php?lang=english

[TONEPUB]

Not me, I'm buying a linear track arm!




You get the "A" for effort though.  It's great to see someone actually applying a little science and hands on vs. just arguing about it!

Much appreciated effort....

[Wayner]

Thanks Jeff,

Perhaps I will cave some day and buy a nice linear tracker, until then........

All I got is lint in the pockets!

Wayner

[rcag_ils]

Have we been making cartridge alignment way too complicated?

I installed a Grado Red on my Systemdek, and used a protractor that I printed out off Enjoy the Music .com, it's a 2 point protractor.

I couldn't get the stylus to land on the 2 points exactly, but I got it very close, it sounded terrible.

Then I used the good old Geodisc, basically a one point protractor, I got the stylus to be dead on to the one point, and it sounded wonderful. Can someone explain that?

[Wayner]

Well, with the 2 point system, you can't be "kind of close". That is what sets the offset angle and as it has been stated before, 1/4 of a degree error can result in horrible results.

Wayner

[rcag_ils]

I rarely start out with a two point system, I did it this time because of all the different talks in this forum, so I wanted to try.

For me, I would put more wears and tears on the headshell more than anything else. I used the Geodisc and get it to be dead on, then check it with a two point system, and the two points are not dead on.

[neobop]

I rarely start out with a two point system, I did it this time because of all the different talks in this forum, so I wanted to try.

For me, I would put more wears and tears on the headshell more than anything else. I used the Geodisc and get it to be dead on, then check it with a two point system, and the two points are not dead on.

Either they were different alignments with different nulls, or your download was not to scale. You can check the spindle to inner grid distance on the download compared to the Geodisc. The Geodisc should be 66mm. If your closer 2-point grid is at 70.29mm, it's a Loefgren B protractor.

Most Systemdek arms use the Linn geometry, at least the original one did. That works with the inner null at 66mm - Loefgren A. With most cartridges it won't reach 70.29.
neo

[Wayner]

Neo, is the Geodisc a Baerwald alignment?

Then with a one point alignment system, it's hard to have an argument, there is nothing to conflict with the position. On a 2 point system, there are the 2 position grids that must end up with the same alignment (like with the front of the cartridge). When the cartridge looks the same on both sets of grids, then you have a good overhang. The 2 point system does 2 things. It first sets overhang for that particular null point set, and at the same time, sets offset angle.

I like the 3 point system as it is more accurate. First the overhang is set, then the 2 null points align the offset.

Wayner

[jimdgoulding]

I was at a bud's house a few nights ago and he has a Nottingham Space 294 table and Ace Space 12" arm and came away thinking there is definitely something to be gained from a 12"arm.  We played three of my albums that sounded superb and his 20th Anniversary 45rpm Famous Blue Raincoat.  I wish I could remember the name of his Salk speakers (started with the letter P, I think) but I can say that they were mellow as a cello.  I've heard and was impressed by AliG's HT3's but these ones didn't remind me of them.  They have an obelisk shape with a ribbon tweet that was completely undetectable.  I couldn't say that about the HT3's*.  Anyway. my bud is re-building an air bearing linear tracker and can definitely expect an offer from me for his Ace Space arm when he's done. 

*Thinking about comments like this or in general, one should always keep something in mind . . room and system difference.  AliG's room, for example, put the listener in the near, very near field.

[neobop]

Neo, is the Geodisc a Baerwald alignment?

Then with a one point alignment system, it's hard to have an argument, there is nothing to conflict with the position. On a 2 point system, there are the 2 position grids that must end up with the same alignment (like with the front of the cartridge). When the cartridge looks the same on both sets of grids, then you have a good overhang. The 2 point system does 2 things. It first sets overhang for that particular null point set, and at the same time, sets offset angle.

I like the 3 point system as it is more accurate. First the overhang is set, then the 2 null points align the offset.

Wayner

Both the Geodisc and Dennesen are Baerwald (Loefgren A). It does make it easy. The only thing is, when aligning you have to be careful that the platter doesn't move. I've check both against a 2 point Baerwald protractor, like DB Systems, and it comes out perfect. 

Baerwald has a lot going for it. While getting near equal error at beginning, middle and end, the overall amount of error (tracking angle) is good. Maybe a bit worse than Loefgren B, but end of record performance is better. Lots of people have problems with end of record. Looking at that (end) from the perspective of tracking angle, Stevenson is by far the best, but other compromises make it unacceptable for many.

I've found that effective length has a lot to do with it. IMO arms with less than 235mm eff length really need Baerwald alignment. With Stevenson, 9" arms don't sound good at the beginning. Maybe there are 9" arms that, with a particular cartridge can get Loefgren B, I don't know. If it sounds OK at the end, then why not. With longer arms try whatever you can get to line up. All the particular problems diminish with length. Although I must say, arms between 9.5" and 10.5" usuallyseem best to me.
neo

EDIT: to avoid any confusion, when I said tracking angle (above), I mean horizontal or alignment.

[neobop]

I posted, on one of the other threads I guess, about using a straight line calibrated protractor, with no grids as such. It has parallel lines going the length. With it, you can get nulls anywhere from 60 to 150mm.

Cartridge stylus to mounting bolt distance varies and arms are designed to use factory recommended alignment. These are factors that limit your options choosing a particular alignment. If you find yourself a couple of mm short of a particular alignment, say Loefgren B, you could either move your arm a few mm toward the platter, or try an in-between alignment.
Baerwald - 66 & 120.89
Loefgren B - 70.29 & 116.6
If you can only go out to 68mm and get it squared up, see if it is also squared up around 118 or 119. It should be, and you'll have a Loegfren A/B 

You can get that protractor on the same page as the others. Scroll down to Chpratz and click on the picture. Take your printer off auto-size and check for correct distance:
http://www.vinylengine.com/cartridge-alignment-protractors.shtml

Sometimes you can modify to get what you want. I have one table with a removable SME type headshell. A Sony PS-X50. The stock alignment is close to Stevenson. Even though the arm is unusually long for that kind of table, the cartridge and headshell limit how I can align. I wanted a lighter headshell anyway, so I got a light weight aluminum one. This one had a lip on the front so I ground it off. Then I elongated the slots with a mini file. Aluminum is soft and it's not hard to do. Now I can use Baerwald with just about any cartridge (I think).
neo

[neobop]

Somebody lamented the lack of standardization with cartridge stylus to mounting bolt distance. An effort was made to have cartridges with standardized spacing. There are some arms that have holes in the headshell, rather than slots, and do not have adjustable mounting distance for the arm, like SME. The Naim Nima I believe is 1 such model. A unipivot that requires carts to have 9mm spacing between mounting bolts and stylus. You might be able to get a list of carts that meet this spec from Naim or a Naim fan club. I understand this is a very nice sounding arm.

Disclaimer - I'm writing this from memory. If I got the name of the Naim wrong, or the 9mm is actually 10, it's accidental. If you're interested in more predictable cart dimensions, this is it, AFAIK.

Warning - Some of these Naim fans might belong to the Flat Earth Society. Approach with caution. I suggest humoring them till you get the information you're looking for. If you engage in prolonged dialogue with some of them, you may find yourself upside down on the underside of the world. It would seem that you're actually right side up, but in fact, you could be in a parallel Universe or time/space continuum.

neo

[Ericus Rex]

Warning - Some of these Naim fans might belong to the Flat Earth Society. Approach with caution. I suggest humoring them till you get the information you're looking for. If you engage in prolonged dialogue with some of them, you may find yourself upside down on the underside of the world. It would seem that you're actually right side up, but in fact, you could be in a parallel Universe or time/space continuum.

 

[analognut]

Neobop touches on what I have to say, but it's not the point he was making and many people will have missed this important fact:

If you are using a downloaded protractor which has been printed out you need to make dang sure your printer has printed the distances exactly right!

There is one particular downloadable protractor which has a long straight line along the x-axis of the printout and another one along the y-axis. The idea is that you measure them to be sure your printer is printing accurately, and if not, the software is adjustable to compensate for the error of the printer. Waaay cool. Not to mention that you can set for Lofgren A/ Baerwald, Lofgren B, Stevenson, or your own custom alignment. And there is more. Also, the small program which does this has a very good help section, which I advise everyone to read. There is a ton of good info in it. Get the protractor here: http://conradhoffman.com/chsw.htm   

[vinylengine]

Have we been making cartridge alignment way too complicated?

I installed a Grado Red on my Systemdek, and used a protractor that I printed out off Enjoy the Music .com, it's a 2 point protractor.

I couldn't get the stylus to land on the 2 points exactly, but I got it very close, it sounded terrible.

Then I used the good old Geodisc, basically a one point protractor, I got the stylus to be dead on to the one point, and it sounded wonderful. Can someone explain that?

Hi,
If you where following the instructions given by Enjoy the Music you will struggle to align to their protractor with some arms.

The correct way of using a two point protractor is to set overhang at the first point, then rotate the protractor a little and place the stylus on the second point to adjust the angle of the cartridge while keeping the overhang set at the first point. You then repeat the process until it's spot on. As long as you don't run our of adjustment slot, you will be able to get perfect alignment at both points using this method.

Enjoy the Music say you should keep their protractor stationary while swapping between points, but the correct angle between the two radial lines on the protractor is different for every length arm so it will be impossible to align at both points with some arms. The angle is a gimmick - to align at both points you should rotate the protractor. Used properly it's an interesting alternative to Lofgren based protractors (eg Lofgren B, Baerwald and Stevenson) as it uses custom null points chosen by ear rather than being chosen to mathematically reduce distortion.

The Geodisc tool aligns the cartridge to the two Baerwald IEC null points (different to the custom points used by Enjoy the Music) but because it has a 'sight line' to locate the grid you only need to set the cartridge overhang and offset angle at one point. However, the accuracy is affected by the need to align the sight line perfectly at the pivot point, which on most arms is difficult to see. Get it right and the result should be good, get the line a couple of degrees out and all bets are off  It's a good tool if used very carefully though.

Regards,
JaS

[hesson11]

Have we been making cartridge alignment way too complicated?

It seems that Well Tempered designer William Firebaugh thinks so. His Amadeus and Simplex turntables feature a fixed-position headshell with no provision for adjusting overhang or tracking angle.

http://welltemperedlab.wordpress.com/2009/02/27/tracking-angle-error/

-Bob

[neobop]

It seems that Well Tempered designer William Firebaugh thinks so. His Amadeus and Simplex turntables feature a fixed-position headshell with no provision for adjusting overhang or tracking angle.

http://welltemperedlab.wordpress.com/2009/02/27/tracking-angle-error/

-Bob

I know Firebaugh'ss TTs can sound very good. I set one up in the late '80s and managed to align a cart on it. IMO not having some provision for alignment is a design mistake. I don't care what they say about outer groove velocity. You can have unacceptable tracking angle error if the nulls are not reasonable. I don't know about the present offerings, but the arm on that early one was too short for that kind of approach.

To be honest, I really don't remember all the details of that table and know nothing about present offerings. Maybe it's like Naim and relies on carts with "standard" stylus to mounting bolt distance?

You've read testimonials from people about misaligning a bit and getting horrendous results. Well Tempered is not exempt.
neo

[vinylengine]

It seems that Well Tempered designer William Firebaugh thinks so. His Amadeus and Simplex turntables feature a fixed-position headshell with no provision for adjusting overhang or tracking angle

Hi,
It's an interesting viewpoint and one that seems to be shared by Naim in the design of their ARO tonearm?

Using a protractor for cartridge alignment is all about reducing tracing error/distortion as much as possible. FWIW in a well designed 12" arm like the SME 312 having the stylus overhang out by just 1mm doubles peak distortion and 2mm nearly quadruples it (the effect is slightly lessened in shorter arms but still dramatic). Of course, whether an increase from 0.504% to 1.084% peak distortion (SME312 +1mm overhang) is audible is open to debate? I read that in one study tracing distortion figures of closer to 10% where needed before they became audible, but I'm pretty certain the true figure is lower than that...

Regards,
JaS

[Wayner]

The correct way of using a two point protractor is to set overhang at the first point, then rotate the protractor a little and place the stylus on the second point to adjust the angle of the cartridge while keeping the overhang set at the first point. You then repeat the process until it's spot on. As long as you don't run our of adjustment slot, you will be able to get perfect alignment at both points using this method.

Enjoy the Music say you should keep their protractor stationary while swapping between points, but the correct angle between the two radial lines on the protractor is different for every length arm so it will be impossible to align at both points with some arms. The angle is a gimmick - to align at both points you should rotate the protractor.

Regards,
JaS

Since most 2 point protractors are designed around either Bearwald or Lofgren's null points (where the stylus is perfectly perpendicluar to the record groove), the act of aligning to the 2 points, which usually involves using a grid pattern to match the front flat feature found on most cartridges at each point, will automatically set the overhang and the offset angle.

If we want to align a Technics SL-1200 to Lofgren's B curve, with null points at 70.285 and 116.604, and we know that the spindle to pivot distance is 215 mm, going back and forth (you have to move the protractor) from point 1 to point 2, checking the alignment of the front of the cartridge with the grid, and repeating this tedious process until the cartridge front looks completely parallel to the grid at both points will, theoritically put the overhang at 18.282mm with the offset angle at 23.613 degrees. That is because this overhang, along with the offset angle (even when they are unknown) are the only 2 values that will produce the 2 desired null points. No other overhang and offset angle value for a 215mm S to P distance will produce the same effect.

Now I do agree with vinylengine that doing the 2 points alone still has a tolerance problem, because the human eye has difficulty (even when paralleling the cartridge to the grid) with a degree of accuracy. Setting the overhang first, and now this value must be known, will reduce the error factor and actuall make the process much easier.

The only physical feature that will stop any tone arm from achieving any popular null positions is just plane real estate. That means, are the slots long enough to move the cartridge where you need it. Some tables only offer 2 holes, and this is very piss poor designing, or perhaps it's a lack of understanding, regarding cartridge alignment.

Here again is the CAD drawing of the Technics that I mentioned:

 

Wayner