[Wayner]

Please help unmess the confusion I am having with stylus location on my RB300 arm. I think there are lots of incorrect data out there on this arm. I bought my P3 used and didn't receive any manual or alignment tools. Pete Wriggle Audio claims the arms length from center of pivot to the end is 245 mm. That would be about 9.64"........NOT! it's length is more like 9.44" or 240. That is interesting cause the stated distance from platter spindle to center of arm pivot is suppose to be 222.97mm and an over hang of 17.23mm. That all adds up to 240.2mm from tonearm pivot (center) to stylus. For all practical purposes, that puts the stylus almost even with the end of the arm (vertically). Can anyone with a jig do some measuring for me, or look at your tonearm and stylus, are they aligned like mine?

Wayner

[TheChairGuy]

http://www.vinylengine.com/tonearm_database.php?make=Rega&sort=eff_length&ascdesc=ASC&type=1&pass=null&Search2=Search

John 

[Wayner]

Those are horrible numbers. The Baerwald curve looks terrible. 237mm length, 15 o/h, 21.63 o/s are not recommended by me. Where did the vinylengine get this (bad) info? It also puts the null points @ 60 and 115 whereas they should be at 66 and 120 and some change. tracking error is up to 2.5%

Wayner 

[TONEPUB]

Hi there:

Not sure if this will help, but if you send me an email
tonepub@yahoo.com

I do have the pdf of the manual for the RB300.  Happy to
send it your way.

[jrtrent]

Those are horrible numbers. The Baerwald curve looks terrible. 237mm length, 15 o/h, 21.63 o/s are not recommended by me. Where did the vinylengine get this (bad) info? It also puts the null points @ 60 and 115 whereas they should be at 66 and 120 and some change. tracking error is up to 2.5%

Rega does not use Baerwald alignment.  As far as I know, their alignment scheme is unique but very close to Stevenson.  All alignment methods (some popular ones are Baerwald, Loefgren, and Stevenson) for a pivoted arm are a compromise, and each has a different set of null points (Baerwald 66.0, 120.9; Loefgren 70.3, 116.6; Stevenson 60.3, 117.4), but each seeks to get the best out of the listening experience.  From what I've read, Stevenson alignment recognizes that the same degree of tracking angle error results in greater perceived distortion at the tighter inner groove than nearer the outside edge of the record, so the attempt is to minimize tracking angle error at the end of a record side at the expense of slightly greater tracking angle error at other points on the record.  This doesn't make it bad, just a different choice in compromises.  A friend who went from a turntable with Baerwald alignment to a Rega found he enjoyed cleaner, less distorted reproduction of the inner grooves of his albums without a noticeable deficit elsewhere.

[Wayner]

jrtrent,

Yes, even with the Baerwald template, distortion is higher at the beginning of the record. As it is, I went back to the original numbers of 223mm for spindle center to tonearm pivot center with a 17.23 overhang and 22.894 offset angle. These are supposed to be the real numbers according to Wriggle Audio. The curve those numbers produce are almost (but not exact) as the prefect Baerwald. That puts the null points at 66mm and 120mm. I am amazed at how much confusion concerning product specifications  there is around Rega products. Rega doesn't seem to want to entertain customers as all the inquiries seem to go to the nearest dealer, which I'm not really interested in talking to anyway.

Thanks for input.

Wayner

[TONEPUB]

A lot of that confusion probably stems from the top. Roy Gandy
doesn't think VTA is a big deal and he pretty much made the tables
to go with their cartridges, where you screw three screws on and
forget it.

[PumaCat]

As pointed out, Rega doesn't use Baerwald number, but Stephenson null points. You can find a protractor using Stephenson null points at Vinyl Engine.

[Wayner]

Any tonearm can be set to anyone of these guy's curves, wheather its Baerwald, Stephensen or Loefgren. They all use the same basic arm length, overhang and offset angle. Where they differ in their calculations is where the null points are. Also, this has nothing to do with VTA.

There is a geometrical relationship between the 3 factors of overhang, offset angle and arm length (stylus to pivot center). As the the arm becomes longer, the offset angle becomes less (depending on overhang). If you have CAD software, you can discover that yourself.

The null points are 2 geometrical points on the record where the stylus is perfectly parallel to the record grooves. It only happens at two points. The problem is most of us use an arcing tonearm, but the record master was cut using a linear tracking lathe. It cut the grooves in a straight line from outside to inside. When you use an arcing tonearm, the obvious thing is that the arc can't follow a straight line. These guys (Baerwald, etc) did some geometry to discover the best place for the stylus tip in regards to the tonearm design, to keep tracking error and tracking distortion at their lowest possible level.

You guys need to go to http://www.enjoythemusic.com/freestuff.htm and find the Baerwald/Loefgren "B" Excel curve generator. When you find out the specifications or already have them, you can enter the values into the Excel spreadsheet and see how your particular set up will generate a curve. The values I have used generates a very nice curve, almost exactly matching the theoretical. The Excel spreadsheet will calculate where the 2 null points are, what the tracking distortion is thru the sweep of the arm and what the tracking distortion is the same sweep.

The important thing to do is to set your stylus to the null points you get from the calculations. This may prove kind of difficult if you do not have a CAD program. I have drawn out the two null point positions and created horizontal and vertical lines around the points (front and sides) so that I can Parallax the front surface of my cartridge (which is flat) to the lines. I print this out full scale, cut the spindle hole out and there is my Rega arm alignment jig.

How does it sound? awesome! Last night there was some very good vinyl listening. I need to get rid of some motor rumble (see my project blog) but in the end this table will be sweet.

Wayner

[jrtrent]

Any tonearm can be set to anyone of these guy's curves, wheather its Baerwald, Stephensen or Loefgren. They all use the same basic arm length, overhang and offset angle. Where they differ in their calculations is where the null points are.

A little overstated, I think.  Yes, they all use the same basic parameters of arm length, overhang, and offset angle, but, as an example, some arms designed and mounted for Stevenson alignment can lack sufficient range of adjustment to achieve the overhang needed for Baerwald, Rega's RB100 on the P1 being an example (not to mention the underhung, zero offset angle arms used on some DJ 'tables).  Using Baerwald alignment on a Rega turntable also means losing the increased rigidity of the 3-hole mounting scheme used for most of their cartridge range.

I agree that John Elison's spreadsheet is a great tool that I've learned a lot from (plus it's just fun to play with!).  For those who can't access it (such as myself, not currently owning Microsoft Excel software), below is a link to a post by Mr. Elison with respect to the tracking error and distortion using both Baerwald and Rega's own alignment on a Rega arm.  Baerwald achieves the same distortion level at the innermost groove, the peak between null points, and the outermost groove.  Rega achieves zero distortion at the innermost groove but has a slightly higher distortion peak between the null points and at the outermost groove.

http://db.audioasylum.com/cgi/m.mpl?forum=vinyl&n=795129

By the way, I use Baerwald alignment myself on both my LP12 and Well Tempered as I like the ease of use of the Baerwald-based alignment tool I've used for the past 23 years (Geo-Disc) and have no complaints abou the sound.  It could also be noted that Rega alignment, and the similar Stevenson alignment, loses its inner groove distortion advantage for records that aren't cut that close to the center (a lot of my classical collection are, but very few from other genres).  But again, Rega's alignment choice is not a bad one, just a different one.  If I used a Rega 'table and cartridge, I would gladly give up Baerwald alignment for the increased rigidity of their 3-bolt mounting--now that's a difference I can hear!

[Wayner]

jrtrent,

I agree except I don't really like the Rega cartridges. As far as using the Baerwald alignment, I'm just plugging in Rega values and that what ya get. It's a nice looking curve. I will check out your suggestion (I'm not that vein).

Wayner 

[Wayner]

Ya, I thougth I've seen that curve before. First null point at the usual end of record, second one closer than normal. Rega traded off some early distortion values (that are higher then Baerwalds) to clip the end of record distortion. Maybe someday I'll try it.

Maybe here is a good place to put Rega's arm specifications:

1. Distance from platter spindle center to tonearm pivot center: 222mm.
2. Overhang: 15mm
3. Offset angle: 21.596 degrees.

For the record, I'm using these numbers to get the baerwald curve:

1. Distance from platter spindle center to tonearm pivot center: 222.97mm
2. Overhang: 17.23mm
3. Offset angle: 23 degrees.

Wayner

[Wayner]

I'm stuck using the Baerwald curve on my new turntable project (see my project topic) as I set the arm to spindle distance at 222.97mm. If I put my Rega RB300 arm back onto my P3, I'll try the Rega settings.

Wayner