My new alignment template generator

the thin end of the wedge
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Conrad Hoffman
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My new alignment template generator

Post by Conrad Hoffman » 21 Jan 2009 15:34

Ok, I admit it. I tested this on the unsuspecting folks at the asylum first. After a few revisions, here's my cartridge arc alignment template and strobe disk generator. It's far smaller than bitmaps of the same thing, plus you can choose your specific pivot-to-spindle distance, groove radius and alignment strategy choice. It also prints pretty darn nice strobe disks. Freeware, no viri, no strings attached. Please let me know what you think.

http://www.conradhoffman.com/chsw.htm

Note: this program is for Windows systems only

JaS
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Post by JaS » 21 Jan 2009 16:11

Hi,
I haven't had a chance to check a printout yet but from a quick 'print to PDF' it looks very good!

It's shockingly simple to use, even with the ability to choose different alignment methods, inner and outer groove diameters and X/Y print error correction.

Nice work. All you need to do know is find a way for it to align the cartridge without the user getting out of his chair :)

Regards,
JaS

scho2684
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Post by scho2684 » 21 Jan 2009 17:19

=D> Very, very nice!
As stated above, very simple to use, good work!

Regards,
Marco

Conrad Hoffman
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Post by Conrad Hoffman » 24 Jan 2009 03:58

Minor news flash- I just uploaded version 1.04 that accommodates longer tonearms without going off the paper. Nobody asked for it yet, but I figure somebody with a 12" tonearm will be along sooner or later!

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Post by Conrad Hoffman » 26 Jan 2009 07:16

Last changes for a while- added the 45rpm ring to the 50hz strobe disk, fixed some dumb text errors and added some notes. Give this thing a try!

Klaus R.
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Re: My new alignment template generator

Post by Klaus R. » 26 Jan 2009 11:28

Conrad Hoffman wrote:...plus you can choose .... alignment strategy

I had a look and saw that there's Baerwald, Loefgren B and Stevenson A to choose from. Loefgren was the first in 1938 to develop a solution for this problem, followed by Baerwald 1941, Bauer 1945, Seagrave 1956, Stevenson 1966. Graeme Dennes analysed the various solutions in 1983 and found that they are mathematicall identical to those of Loefgren.:

https://www.vinylengine.com/turntable_f ... php?t=4854

see in particular e-pages 7, 8.

Give credit where credit is due! Baerwald's solution is identical to Loefgren's A-solution. Clearly, in view of these (historical and mathematical) facts, credit should be given to Loefgren, and to Loefgren alone, not Baerwald, and it should read "Loefgren A" / "Loefgren B" instead of "Baerwald" / "Loefgren B".

On a sideline, the only manufacturers that make that (incorrect) distinction (Baerwald, Loefgren) on their websites are Wally Malewicz and Judy Spotheim (La Luce turntable). I have contacted both asking to set the record straight in view of the facts. As you can see, neither has modified the site accordingly:

http://www.simplyblack.net/WVC/index_wally.html (Wally Tractor)
http://www.spj-laluce.com/products.htm (Lyla tone arm)


Klaus

andyr
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Re: My new alignment template generator

Post by andyr » 26 Jan 2009 12:02

Klaus R. wrote:
I had a look and saw that there's Baerwald, Loefgren B and Stevenson A to choose from. Loefgren was the first in 1938 to develop a solution for this problem, followed by Baerwald 1941, Bauer 1945, Seagrave 1956, Stevenson 1966. Graeme Dennes analysed the various solutions in 1983 and found that they are mathematically identical to those of Loefgren.

Klaus
Hi Klaus,

So where does that leave us wrt the Stephenson alignment? :?

As I understand it, he simply chose different inner and outer null points? This has some relationship to the radius of the inner & outer grooves but, if I decide that most of my LPs have different inner & outer groove radii, what is the logic to choose the best alignment?

Regards,

Andy

missan
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Post by missan » 26 Jan 2009 12:02

From what I can see, the Stevenson null points is according to design 1C.
Not beeing an expert on this, I have normally presumed that the design 1B was what Stevenson recommended, and what is normally also referred to as Stevenson. The 1C is a little more suited for 7" records.
missan

Klaus R.
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Post by Klaus R. » 26 Jan 2009 13:34

Andy,

according to Graeme, Stevenson A uses the same equations as Löfgren with a different goal, i.e. zero distortion at the inner groove. So yes, basically it's only about different null points.

The problem with Stevenson A is that, while the outer radius is about the same all the time, the inner radii are really different, so which one do you choose? Whatever the approach or radius is you are using, it's a compromise anyway. You get optimum results for records having that radius and less than optimum results for all the others. I measured the inner radii of my collection and as it happens, the inner null point is approx. at the average inner recorded radius.

Has anybody compared Löfgren A and Stevenson A to see whether it makes an audible difference?


Klaus

JaS
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Post by JaS » 26 Jan 2009 15:59

Klaus R. wrote:Has anybody compared Löfgren A and Stevenson A to see whether it makes an audible difference?
Hi Klaus,
I tried Stevenson, Löfgren B, and Baerwald (!) and to be honest I found it very difficult to hear repeatable differences between them. I'm always surprised when people say they hear night and day differences or that a particular protractor makes a massive difference compared to any other using the same null points.

I use Löfgren A null points as technically they should be better than Stevenson and they suit the slots in my arms better than Löfgren B, but I'm not obsessive about it :wink:

Regards,
JaS

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Post by Seb » 26 Jan 2009 16:32

Jas wrote: I'm always surprised when people say they hear night and day differences or that a particular protractor makes a massive difference compared to any other using the same null points.
me too

best regards

Seb

Conrad Hoffman
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Post by Conrad Hoffman » 26 Jan 2009 17:32

Glad to see some interest! I don't have any problem changing Baerwald to Löfgren A, but called it Baerwald because that's the most popular name and I didn't want to clutter up the screen with a dual name. I used the wonderful Graeme Dennes paper to sort out the formulas and, as he says, if Löfgren wrote the only paper on alignment, we'd still be doing things exactly the same way.

I learned something interesting while experimenting yesterday. When the stylus is off the record or template, the cantilever forms an angle to the arm. You knew that. When the stylus is on the record or template, the angle is reduced. You knew that too. What I hadn't thought about was that this increases the effective length of the arm slightly. Not much, not enough to really measure, but enough to put axial force on the cantilever. Because the arm pivot isn't in line with the cantilever, the cantilever will be deflected in the cartridge body towards the spindle. IMO, this makes aligning to the cantilever more problematic, especially with high compliance cartridges. Once friction is overcome, say playing a record, or if the template had zero friction, the cantilever re-centers.

What do people have to say about this- I'm far from being any expert on the topic?

Conrad Hoffman
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Post by Conrad Hoffman » 27 Jan 2009 02:32

Your wish is my command- Baerwald has been purged and replaced with Löfgren A, though I did keep a note in the Help screen for those who are looking for Baerwald. Also defaulted the selection to Löfgren B, as that seems to be the most logical choice for most people, though as I understand things, some arms will only allow Stevenson, which accounts for most of the interest in that. Any comments on the axial force issue? I added some notes on that as well.

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Post by Conrad Hoffman » 27 Jan 2009 05:01

I'm in favor of naming things after the originator, and here it's no big deal. OTOH, the Whetstone Bridge was actually invented by Christie, but if I talked about a Christie Bridge, everybody would think I'd flipped!

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Post by Graeme Dennes » 27 Jan 2009 14:57

If I could add a couple of points to an interesting discussion.

As a background note re null points. Null points are based on (ie, are calculated from) the inner and outer groove radii selected for alignment optimisation purposes. They are outputs only. They are not the drivers of the optimisation process, but the consequences of it.

Of course, they may be specified for use in an alignment procedure or for when using a particular alignment tool, but their specifying does automatically pre-determine the values of the inner and outer groove radii (from which the null points were calculated).

As a background note re the Stevenson A alignment. Stevenson's goal was to minimise (in fact to make zero) the weighted tracking error (WTE) and the resulting distortion at the specified inner groove radius. In and of itself, this was a worthwhile outcome. However, under the Stevenson A alignment, the WTE and the distortion occurring over about 75 percent of the record playing time is greater than that which occurs under the Löfgren A alignment for the same conditions (ie arm length and groove radii). Further, the Stevenson A alignment is only significantly better than the Löfgren A alignment during the last 3-4 mm of the record playing surface (usually less than one minute of playing time).

Plotting the WTE of these alignments will confirm the above. It is primarily for these reasons that the Stevenson A alignment was never going to be broadly accepted and adopted.

Practically, this leaves us to choose between the Löfgren A and Löfgren B alignments, although the Löfgren A alignment still continues to be the most widely adopted alignment standard.

Graeme Dennes

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