My new alignment template generator

by **Joesph55** » 05 Mar 2009 06:11

I have a few questions about setting up and using this program. I am a complete noob, dont understand the math at this level , but I would like to try and put my first cartridge on my vintage Pioneer turntable. My first question is about the groove radius selection. Could someone please give an explanation on which is the correct one for my purpose, is there a standard that is used for a majority of vinyl? Is there reading on this subject someone could suggest. I did a printout of the Lofgren A protractor, I used typical as the groove radius (until I understand more) My Pioneer Pivot to spindle is 206.5mm, when I printed the protractor the specs on the printout for effective lenght and overhang are way off compared to the factory specs. I realize that the protractor math is more precise than the specs Pioneer put in there manual. Once I find out which is the correct groove radius, should I follow the specs on the protractor, and not pay attention to the factory specs, As an example, the protractor spec gives my tonearm an effective lenght of 225.391, with an overhang of 19.391, the manual for my table states the effective lenght is 221mm with a 15.5mm overhang. Sorry for the dumb questions, noob here :roll:

Regards, Ed

by **JaS** » 05 Mar 2009 13:37

Joesph55 wrote:My first question is about the groove radius selection. Could someone please give an explanation on which is the correct one for my purpose, is there a standard that is used for a majority of vinyl?

DIN is the Japanese and IEC the international standard for maximum and minimum groove radius. Obviously records vary so in theory you could optimise the protractor null points for an average based on your records. Alternatively just use IEC and you should be OK for anything you throw at the turntable.

I realize that the protractor math is more precise than the specs Pioneer put in there manual. Once I find out which is the correct groove radius, should I follow the specs on the protractor, and not pay attention to the factory specs

The overhang, offset angle and angle of the cartridge in the headshell will change depending on the null points the protractor uses. For example, if you choose Baerwald or Loefgren and the arm manufacturer originally specified Stevenson (or similar) alignment then you should ignore the manufacturers specs - used correctly the protractor will set the overhang and offset angle accurately for the chosen alignment.

Regards,
JaS

by **Joesph55** » 06 Mar 2009 06:32

Jas,

Thank you kindly for your reply, that is what I neeeded to know. I am a bit nervous as this will be my first cartridge install :shock:

Regards, ED

by **Axon** » 06 Mar 2009 07:46

Conrad Hoffman wrote:I haven't done exactly what I've described above, but here are some photos that I think illustrate the problem, at least with very compliant cartridges like my OM30-
<snip>
From this, I'd have to say that aligning to the cantilever with high compliance cartridges is problematic. IMO, this is probably a worst case situation, but the error sources are real. It seems that either a bit of pressure on the platter is necessary (risky and hard to be consistant), or one is better off aligning the cartridge body. For less compliant cartridges, or where the geometry somehow prevents the cantilever from deflecting, aligning to the cantilever makes a certain amount of sense.

Comments? Am I crazy?

A part of me wants to say that this deflection may also be due to uneven suspension wear, although I don't have much to back that up.

Moving the platter while the stylus is down will cause the contact friction to increase for a fraction of a second, causing a short increase in effective length beyond its stationary value (but close to the length while in play). I'd imagine that as this goes back to normal with the manual platter rotation stops, the cantilever will spring back up and this will still cause some minor change in cantilever angle. Hard to quantify though.

As far as alignment is concerned, isn't the simplest solution simply to set the VTF to 0.1g while aligning, and just live with the effective length deviation while in play? No downforce, no VTA change, no problem.

by **Conrad Hoffman** » 07 Mar 2009 02:08

The deflection is the same for both old and brand new styli, and it took me a long time to decide it wasn't some flaw with the arm or cartridge. IMO, changing the VTF is a perfectly good solution, it's just that I fear few people recognize the problem and end up with a flawed alignment because somebody convinced them aligning to the cantilever is vastly superior, when in fact it has many pitfalls. If one can't duplicate the cantilever position that occurs during actual record play, there's no point in aligning to it.

by **Audie** » 27 May 2009 19:45

Conrad, great work on your alignment protractors. Much appreciated.

Re. The deflection of the canterlever when lowered on to an alignment point on a stationary protractor.

I have always reasoned rhat this was due to a force created because the canterlever is unable to take up a neutral position on the protractor, due to being impeded in it's movment by the template surface.

This restriction will vary depending on the degree of smoothness of the template surface, being severest if an indentation is made at the alignment point.

As the arm is lowered to the alignment point, the stylus, being restricted in it's movement on the stationary protractor, will create a force on the canterlever, tending to push the arm upwards. However, the compliance of the canterlever suspension will instead result in the canterlever being deflected, instead of the mass of the tonearm.

I've always gently adjusted the template to try to move the stylus slightly forward, maybe 1/2 mm, to relieve that tension in the canterlever.
In doing so the canterlever will align as it was before being lowered to the record.

Audie.

by **Audie** » 30 May 2009 06:28

Part 1

Re. my last post: It was made in a sleep deprived state, around 4 AM, so may need clarifying.

To begin, the large deflection of the canterlever of the high compliance cartridge in Conrad's photo, suggests to me it is due mostly to arm bias being applied.
Although the arm bias may have been set to the zero bias mark, it may still be applying bias. This is not unusual.
In such a case, the bias should be moved below the zero mark, if possible, to correct this.
IMO, a deflection of the canterlever sideways due to the cartridge suspension being restricted from settling (as a result the applied VTF) would be much less than depicted.

Audie.

by **Audie** » 30 May 2009 06:44

Part 2. ( to prevent being timed out - happens a lot to me- slow typer)

A cartridge suspension which is prevented from assuming it's correct attitude, due to the restrictive nature of the template surface, will introduce another inaccuracy into the cartridge alignment process.

If a pin mark is made at the null point, to overcome the difficulty of positioning a stylus accurately, this restriction to movement of the stylus is greatest, and could be as much as 0.5mm.
This amount of error is significient on it's own, and more so when added to the other visual alignment errors inherent in the alignment process.

A simple remedy, I feel, is to gently move the template forward from the stylus ( away from the arm pivot) to let the suspension relax.
The aim is to reduce the error.
A glass template, although not frictionless, may need little or no adjustment.

Audie.

by **Conrad Hoffman** » 03 Jul 2009 05:51

Haven't been around much lately, but for those still reading I want to offer a simple experiment. Get a piece of thin solid wire, maybe 6-12" long. About 1" up, bend the wire by, I dunno, 20-40 degrees. Now, pretend the long straight portion is the tone arm, and the short part is the cantilever. The bend represents the offset and resulting angle. Pull on the ends of the wire. The angle of the bend will open up. Or push, and it will close down. This is exactly how the combination of cartridge offset combined with friction drives the cantilever off center. It's a fundamental flaw of pivoted tone arms where offset is used to get the very low tracking angle errors we want. IMHO, tracking angle error is important, but the dynamic moments applied to the cantilever while playing a record are highly undesirable. So far as alignment, a low friction template is desirable, also to reduce the chance of stylus damage, but I don't think it will ever be low enough that the problem can be dismissed. BTW, I never understood (maybe still don't) just what anti-skate was really doing, but as the friction opens the angle and deflects the cantilever, the correct amount of anti-skate will bring the deflection back to zero. Or somewhere close.

by **Logan** » 23 Jul 2009 04:46

For what it is worth:

I recently purchased a new turntable and the distributor aligned the cartridge (on a Michell TecnoArm - a highly modified Rega RB250) with the effective and very expensive Dr Fieckert device.

I printed off your new Stevenson 222mm protractor, and find that the cartridge is perfectly aligned with this. So I can be quite confident checking with your protractor at a saving of some $300.

Incidently, printing on mylar film for OHP transparencies is much superior to printing on paper.

by **Alec124c41** » 23 Jul 2009 06:05

Logan, listen a while to your set-up, then try a Baerwald protractor. You might like it better.
BTW, I like to print protractors on photo paper.

Cheers,
Alec

by **blakep** » 03 Aug 2009 19:45

I have a question that may simply be a variation on Ed's above. Forgive me if it's a stupid one.

I'm about to mount a Jelco 750D on my Gyro. It looks as though Jelco specified Stevenson as using the generator (214 Pivot to Spindle) in that Stevenson gets me closest to the Jelco specs of 229 effective length (228.995) and overhang of 15 (14.995).

Given that Lofgren A seems to be the preferred alignment in this thread does anyone have any opinions on which protractor I should use if the Lofgren protractor gives pretty significantly different results on the effective length and overhang (overhang can be out by as much as 4.13 mm and effective length by 2.75 mm or so). I can see the overhang being an issue with cartridge mounting possibly and my thoughts are that I should just stick with the Stevenson alignment that gets closest to the manufacturers specs. Is that thought process flawed?

If I did try the Lofgren (is it even worth it in this case?), am I correct in assuming that I should be trying to get to the closest "effective length" spec using the generator as opposed to the closest overhang spec?

Opinions welcome and thanks in advance for any advice and also to Conrad for so generously making this available!

by **Alec124c41** » 03 Aug 2009 21:56

If you are going to try different alignment protocols, forget the effective length and overhang specs. These only pertain to one set-up.
Baerwald will give longer figures than Stevenson. You can't use Baerwald, and try to match Stevenson numbers.
Print out both protractors. If your table is set to Stevenson, optimize it and listen for a while. Then realign to Baerwald, and listen some more. Decide for yourself which sounds better to you, with your set-up.

Cheers,
Alec

by **cam08529** » 05 Aug 2009 04:01

Another noob question-I apologize in advance if it has already been asked and answered. I just stumbled upon a Dual 1019 with a good head shell but I need to install a new cartridge. I don't have the jig Dual supplied with the table to install the cartridge. I measured the spindle to pivot distance at 185mm, left other stuff as typical and adjusted for printer error. So far so good but the arm has a hook in it where the tube attaches to the arm. My alignment points can't be right because they are at the very tip of the head shell. With this head shell the cartridge can't overhang because there is a lip in front of the head shell.

Can the protractor take into account arms that have a "dog leg" in them? If so, how do I do it?

Regards

Jeff C