[vinylengine]

I aligned the cartridge with the Geo-Disc, recheck it with the two point protractor that I printed off "enjoy the music". They come very, very close, good enough for me.

That's good - they may be close but they shouldn't quite match - the null points on the "enjoy the music" protractor are oddball as they aren't Baerwald, according to the designer they where chosen by ear to match his tonearm and the average groove radii of his records (!)

It just goes to show how difficult it is to visually confirm two completely different alignments.

Also most stylus are not cut to the same shape as the record cutting stylus, so you'd have to get something like an Ortofon if you want precise reproduction.

You're right there. My Goldring uses a Gyger S stylus but it's a pig to tune in because (a) the stylus is tiny and (b) it's shaped to sit low in the groove. On the other hand with a spherical stylus you have to get alignment way out to hear a significant deterioration of sound, but it's never going to sound as good.

Regards,
JaS

[Wayner]

I don't know where I got the numbers from, that was long ago. Somebody has them published.

Anyway, yes now we are connecting. The longer arms produce lower distortion curves because the arc across the record gets flatter and flatter. If we had a 10 foot arm, it's arc would almost look like a straight line in a short section. Now i think your seeing where I'm coming from.

To your second part,

 "Also are you saying that this is the only mounting distance from which you can align to points calculated using Baerwald's equations?"

Yes. One arc, one arc center. However, there are 3 factors that make the entire game very confusing. Those factors are pivot to spindle, overhang and offset. I haven't a clue how many combinations of different variables can give almost exact results.

As an example with your Technics offering, you really extended the overhang, but decreased the offset angle and it dialed really close.

It may take a super computer to figure out all of the possiblites.

The whole thing forms a triangle

This has been a head banger. Are you getting tired?

Wayner  aa

[Wayner]

By the way, for those of you who are reading the thread, vinylengine is a worthy opponent! I truly expected challenges, and I got them. This is what makes us great. The fact that we can disagree on just about everything (you bastards!), yet there isn't a better place I'd like to spend my Saturday!

I do think the world of many of you and I'm sure this debate will continue.

My advantage is that I have a very powerful CAD system. I can do in minutes what would have taken Baerwald and Loefgren days and days. That's technology for you.

And many of you may wonder who is going to be the winner. I don't think there is going to be one. That's OK too. I'm glad vinylengine joined in our forum and hope he continues, just to keep me on my toes.

For now, I have a Weber Grill calling my name and a wife hoping I can wip up some viddles. There will also be some beer and tunes in the garage, and yes it will be vinyl.

A little Boston or Yes or maybe the Beatles?

Wayner 

[BobM]

Well I check my cartridge wih the Lofgrin A (Baerwold) curve I printed out and the stylus lined up pretty much perfect, but the angle of the cartridge body was off just a tinge. So I moved it a bit and re-proved that the stylus tip is still spot on the crosshairs for both points (it is).

So I'll try and give it a listen a little later on this afternoon/tonight o see if I hear any difference. I'm absolutely certain that it will be phenominal due to the after effects of the Pina Colada's that I am enjoying at this moment. (did I spell this whole message corretcly?)

Bob

[vinylengine]

"Also are you saying that this is the only mounting distance from which you can align to points calculated using Baerwald's equations?"

Yes. One arc, one arc center. However, there are 3 factors that make the entire game very confusing. Those factors are pivot to spindle, overhang and offset. I haven't a clue how many combinations of different variables can give almost exact results.

As an example with your Technics offering, you really extended the overhang, but decreased the offset angle and it dialed really close.

I'm almost ready to call it a night as I'm knackered, but it's been interesting

I've been re-reading the Graeme Dennes papers 'analysis of Loefgren geometry' and 'is the Loefgren solution unique?' and I think the error in the measured offset angle in the CAD plot may be due to measuring to the default 'Baerwald' null points? For all practical purposes aligning to 60mm and 120.9mm is fine for any length arm (providing you have room in the headshell) but they are not exact and you should be sure to use 65.998 and 120.891 on the plot. If I get a chance I'll drop Autocad back on my laptop and have a play this week.

Interestingly in the paper Graeme gives figures for his 'perfect Loefgren A solution' where he adjusted the offset angle and overhang to make the weighted tracking error exactly equal at the 3 points and the lowest possible at these three points for a given effective length and inner and outer groove radii.

He doesn't suggest you should try to use them in practice, but in theory these should give good results on an arm with a 233.4848008400749 mounting distance 

Effective length: 250mm
Offset angle: 21.9625719271288 degrees
Overhang: 16.5151991599251 mm
Inner null radius: 65.9785567649371 mm
Outer null radius: 121.021861771216 mm

Somehow I don't think my eyesight is up to it!

As an example with your Technics offering, you really extended the overhang, but decreased the offset angle and it dialed really close.

These are the figures I get for Baerwald alignment from 3 separate tools, but I'd like to plot several more examples to confirm it? Of course this doesn't mean it's practical to place the cartridge in the right position in every arm. For example SMEs would be impossible as they have fixed effective length but adjustable mounting distance...

Regards,
JaS

[vinylengine]

So I'll try and give it a listen a little later on this afternoon/tonight o see if I hear any difference. I'm absolutely certain that it will be phenominal due to the after effects of the Pina Colada's that I am enjoying at this moment. (did I spell this whole message corretcly?)

LOL I hope you dialled it in before you opened the bottle

Regards,
JaS

[Brett Buck]

The tonearm is made from wood and is 60cm long! The Horo WJE 168, according to designer Luigi Pasqualini (shown), was designed as a "musical instrument" would be. The price has not yet been announced.

Wouldn't that produce awful results, as the sound reproduction would be contaminated by the resonating frequency/characteristics of the tone-arm?

   Absolutely. This is why guys who are strictly musicians with no engineering training or experience are frequently terrible audio engineers. It's "design by analogy" (false analogy in this case). Something along the lines of "Gee, a Stradivarius sounds good, so if I make a turntable like a Stradivarius, it must also sound good". The same logic on the consumer side explains almost all the really idiotic talk about mpingo resonator dots, single-ended triodes, etc.

    Brett

[vinylengine]

OK I think I've got it 

If you're setting out to prove/disprove whether the offset angle is achievable you really need to use a similarly high degree of accuracy when plotting the arc and null points.

I plotted the Baerwald arc for a 215mm mounting distance to an accuracy of 3 decimal places using Autocad (as given by the J Ellison spreadsheet and confirmed with the arc generator software).

Here are the figures from the spreadsheet:

inner null point: 65.998mm
outer null point: 120.891mm
mounting distance: 215mm
effective length: 232.817mm
offset angle: 23.664 degrees

I then measured the offset angle at the null points of 65.998 and 120.891mm and got the correct offset angle at both points!



This clearly shows that it is possible to align to Baerwald IEC null points with an arm of 215mm mounting distance by setting the effective length and offset angle as per Baerwald equations.

Regards,
JaS

PS I've never tried plotting the figures before and always trusted in the original research This thread has been very informative.

[vinylengine]

To show that this isn't a one off and the null points on a universal two-point Baerwald protractor are applicable to all arm mounting distances, here's another plot, this time for arms at 222mm (Rega etc), again using the same null points.

Here are the calculated figures:

inner null point: 65.998mm
outer null point: 120.891mm
mounting distance: 222mm
effective length: 239.296mm
offset angle: 22.986 degrees

And here in practice showing that if you align at both null points you will get the overhang and offset angle that Baerwald calculated:



Regards,
JaS

[Wayner]

Good morning vinylengine!

Your up early! I guess you and I were headed down the same course. Below is a printout of the arm in it's travels across the record surface at some evenly spaced intervals. The 2 red circles are the null points. NO I did not carry the decimal point out to 29 places!! Ha, ha.







The angles are hard to read but this is what they read from bottom to top:

88.242
88.890
89.481
90.006 null point (should be 90.00)
90.453
90.804
91.039
91.097
91.028
89.990 null point (should be 90)
88.817
86.915
83.860

So my 2 null points are off cause I didn't carry the decimal out farther.

Isn't this fun?

Wayner 

[Wayner]

And now if we look at the generated curves, we can see the relationship of the tone arm angle (relative to being perpendicular to the groove) in the blue line showing tracking error.



Wayner

[vinylengine]

So my 2 null points are off cause I didn't carry the decimal out farther

10/10 for trying to plot it in the first place though - most folks would have just taken it for granted (me included)

It's also worth noting that in Graeme Dennes paper 'is the Loefgren solution unique?' he proves that there is only one overhang/offset angle that will provide the lowest weighted tracking error at the inner, middle and outer groove radii for any given effective length, and that the Loefgren A equation can calculate these figures.

The fact that the null points to achieve this alignment are the same for all length arms is a happy coincidence that makes a universal protractor work (as long as you have the room to align to it - but that's for another day!).

Regards,
JaS

[Wayner]

I would like to summarize a bit for those who maybe got lost in the translation.

First, we know that null points are directly related to arm geometry and the relative position of absolute perpendicularity to centerline of the groove modulations. We also know these null points can drift up or down the scale depending on geometry of the arm mounting relative to the platter and the overhang obtainable.

We also know that average distortions will decrease with longer tonearms (not the violin tonearm, however! Ha, ha), and inversely increase with shorter lengths. Why? because the shorter radii has a greater arc. The longer radii has a lesser arc. Again, all relative to the physical geometry of the table/arm combination.

Next, we know that a verity of arm/table combinations may pass thru the same null point positions, however we also know that their path will not match Baerwald's "perfect arm" and because of this, distortions at the beginning, or at the end of the record may be  higher (or lower, depending on arm lenght) and in between null points.

The other observation I have is that I have some reservations about departing from the manufacturer's recommended overhang. The reason for this is that some tonearms may physically not be able to reach to that particular distance. I have one on my studio that is at the end of it's slots with no other direction to go.

This is where the playground comes into play. The user may have to fool with many combinations of overhang and offset angle that are within the limits of his/her tonearm/table configuration. I would guess that there are hundreds if not thousands of turntable models and I couldn't begin to guess at the problems that may be encountered.

The goal is the lowest tracking distortion (and average), and the lowest tracking error distortion.

I'm going to breakfast.

Wayner 

[orthobiz]

SOH
CAH
TOA

Sorry, but I wanted to post somethingand I just don't know enough geometry!!

Paul

[Listens2tubes]

This is all very thought provoking, being I have spent mucho time setting up my RB250 using the D B Systems DBP-10 Phono Alignment Protractor. Back in the late 70's this was the real deal. Seems to have fallen into obscurity since though. So Wayner will you be making up alignment cards to order? I would be interested in seeing what changes with the correct null points. 

[doug s.]

Ah, here is the problem. You have to strike the arc using Baerwald's spindle to tonearm pivot center. Any alignment jig that references Baerwald's 2 null points, start with the 210.427mm spacing. You just can't change that number to any distance you want. That is the number the null points are drawn from.

So I could draw your different overhang number, but not from the 215mm distance of the Technics. That would be like digging up your house and moving it over 2 feet.

That, my friend is the whole purpose of this thread. You can't do what you just told me to do.

Wayner 

wayner, this is where i think you may not be getting what jas is saying, and where perhaps some confusion may be left out there for us winylfools.   

afaik, using an alignment jig that references baerwald's 2 null points, you can get a proper alignment with a tonearm of any length, not yust one w/210.427mm spindle to tonearm pivot center spacing.  as jas says, the way to do it is to adjust overhang and offset.  the only changes to the baerwald alignment will be greater error w/shorter tonearms, and less error w/longer arms, when not on the null points...  baerwald's calcs yust happen to use 210.427mm as tonearm length.  (perhaps this is/was the length of a standard/common/popular tonearm?)

doug s.

[doug s.]

The tonearm is made from wood and is 60cm long! The Horo WJE 168, according to designer Luigi Pasqualini (shown), was designed as a "musical instrument" would be. The price has not yet been announced.

Wouldn't that produce awful results, as the sound reproduction would be contaminated by the resonating frequency/characteristics of the tone-arm?

   Absolutely. This is why guys who are strictly musicians with no engineering training or experience are frequently terrible audio engineers. It's "design by analogy" (false analogy in this case). Something along the lines of "Gee, a Stradivarius sounds good, so if I make a turntable like a Stradivarius, it must also sound good". The same logic on the consumer side explains almost all the really idiotic talk about mpingo resonator dots, single-ended triodes, etc.

    Brett

any tonearm 60cm long will sound better than than a standard ~23cm tonearm, all other things being equal.  but, there's the rub - whether or not this violin-bow-like arm is "all other things being equal"!     while i think a 60cm arm is a nice, if impractical solution to pivoted arm tracking error, the execution is critical; i'd think something like carbon-fibre, titanium, etc., might be better - ie: something offering a more rigid platform.  but, perhaps, being 24" away from the pivot, the wood is rigid enough in this application.  certainly does look odd.  i have seen wintage 16" transcription arms, those look plenty weird enough...

doug s.

[Wayner]

Right now I have superimposed 3 arc on one drawing and they all follow a different path. I have the original Baerwald path, the new Technics and Rega path per JaS's new numbers. All 3 paths crisscross each other. And right now I thinking about a new problem.

Most 2 point alignment systems rely on a 3rd vector, that being the theoretical perfect path. Now I have 3 different paths with the same null points. I may need a day or two to think about this one, but I smell trouble.

If anyone here doesn't think this is complicated, come on.

Also, there are tables with shorter arms that will perhaps not even reach this far. I'm thinking Marantz and Harmon Kardon for starters. I don't think there is enough slot to get to the new embelished position.

More to come.

Wayner       

[oneinthepipe]

Wayner:

I've been away for a few days and have been reading the posts on my Treo.

Fascinating stuff.  Way over my head, but your discussion helped me visualize the issues. 

Did the cutter heads use the same geometry or were some records cut differently?  Would differing cutter head settings, if any, effect cartridge alignment? 

I remember some of those linear tracking tonearms from B&O, HK, Rabco (IIRC), Revox, and others.  I don't remember why they didn't become the standard. 

I haven't had the time to readjust the cartridge on my AR EB-101, and after reading your whitepaper, I am not exactly sure what to do, except to use your alignment tool, but I am not sure if I should rely on the factory-determined overhang, unless I have misinterpreted something.

[vinylengine]

Right now I have superimposed 3 arc on one drawing and they all follow a different path. I have the original Baerwald path, the new Technics and Rega path per JaS's new numbers. All 3 paths crisscross each other. And right now I thinking about a new problem.

Hi Wayner,
I think part of the problem is deciding what result we want to achieve I'm busy this week but I'll leave you with more food for thought, and more figures to play with!

Loefgren A
This equation is designed to give the lowest possible but equal distortion at the beginning, middle and end of any given playing field. The idea is that you have a moderate amount of distortion evenly distributed across the record and Baerwald 'rediscovered' this in his paper 3 years later. This applies to any set of groove dimensions and arm length. Neither he nor Baerwald specified the grooves or the arm length as standards had not yet been developed * but the equation has since been applied to the groove diameters of microgroove records and that's where the conventional 'Baerwald' null points come from.

Loefgren B
This equation is slightly different as it gives you the overhang and offset angles that will give the lowest average tracing error and tracing distortion across the record for any length arm. In the case of IEC standard minimum and maximum groove diameters for long playing records the resulting null points are at 70.285 and 116.604mm. If you can align to these you will get the lowest possible average tracing error and distortion.

For the 215mm mounting distance Technics arm in my previous example these are the resulting dimensions (you can calculate these easily using Conrad Hoffman's arc program) - note that for Loefgren B the offset angle is always the same as with Loefgren A, but the overhang has increased.

mounting distance: 215.000mm
effective length: 233.282mm
offset angle: 23.614  degrees
overhang: 18.282mm
inner null point: 70.285mm
outer null point: 116.604mm

So in theory if you can align to these null points, and the only thing getting in your way is the amount of room in your headshell to set the overhang and offset angle, then you have the lowest possible average error across IEC standard records

As I see it the two remaining questions are:

Can my arm align to the Loefgren A or B geometry?
I think this can only be verified by physically trying to align to the given null points. In theory any length of arm can align to this geometry, but the design of the headshell and length/width of slots can make this impossible. If you know the full extent of adjustment of overhang/offset for any given arm you could probably calculate the best null points possible, otherwise you can only verify by experimentation with the known best points (Loefgren A and B or maybe Stevenson?) and the manufacturers original alignment, which to be honest normally sounds fine in practice.

Can I get lower distortion with record X?
In theory you can minimise the distortion for any given record or collection of records by applying the Loefgren equation to a records measured inner and outer groove radii, or the average across a selection from your record collection. Conrad Hoffman's arc protractor generator comes to the rescue here as it will print an arc and null points for your arm's mounting distance, and your choice of geometry (Loefgren A, B or Stevenson) and groove diameters (IEC, DIN or custom).

Regards,
JaS

* Baerwald's paper on arm geometry was published 7 years before the first 12-inch, long play, 33⅓ rpm microgroove record was made.