Confused by "Stylus overhang".

I bought one of these years ago and found it to work quite well.

http://www.turntablebasics.com/

Basically, I masking tape the mirror to the platter. Then I point the sight line to the pivot point on the tonearm, lining that up with thread to confirm an exact line up. Then I tape the platter down with masking tape so that it does not move, and check alignment on the sight line again. Once that's all lined up, I then mount the cartridge so that the body lines up with the box square lines of the outer boxes and the stylus falls exactly on the outer cross hairs. Once mounted, I check everything again, remove the masking tape and mirror, and I'm done.

But to address the OP's question, 'Stylus Overhang' is usually a specification given from either the pivot point on the arm to the stylus point at the other end, or sometimes from the outside of the O ring on the headshell to the stylus point. Turntable manufacturers will pick a particular tonearm geometry and then assign this specification in order to properly align a cartridge and stylus to that tonearm geometry.

There are several common types of tonearm geometric configurations. No matter which is chosen, the attempt is to counter inevitable tracking errors of a pivoting tonearm. You may have heard of linear-tracking tonearms, these were designed to completely eliminate this type of tracking error. But on a pivoting tonearm, at some point or points (called the null point or points) the stylus will be perfectly perpendicular to the groove walls. The rest of the time, there will be an alignment error -- albeit slight -- as the tonearm works its' way through the pivot of travel from outer to inner groove.

The common geometric configurations that Protractors are made from are named Stephenson, and Baerwald. Both assume two null points...so if you picture yourself plopping the needle down at the beginning of a record and playing a whole side, first the tonearm starts working toward Null Point One, sounding cleaner, and cleaner, with less and less distortion. Once it hits Null Point One, it's perfectly in line. From here, it starts to degrade a little bit, but then improves again as it nears Null Point Two. Again, it is perfectly in line. Then it starts to degrade as it continues on it's way to the lead out groove.

Baerwald and Stephenson differ by where they have decided these null points should be. Some turntables sound better with one, some with the other...in fact, some are designed for one or the other. Often, its not known which they were designed for, or if they were designed for them, or one of the manufacturer's choosing. Technics, for instance, seems to be very close to a Stephenson design for most of their S arm turntables.

So one can use a protractor to come up with the proper alignment, OR, if given the overhang specification, one can simply measure the distance from either the pivot to the stylus or the O-ring on the headshell to the stylus and essentially accomplish the same thing. Most turntablists (as I like to call folks who really get into this stuff) end up using a protractor of some sort, as it gives a better visual confirmation that everything is lined up properly and also allows accountancy for slightly askew cantilevers and such.

 

You did well. Curved or straight arm - doesn't matter - think about it. It doesn't matter what curves the arm goes through to get to the stylus - the arm has a pivot at one end and a stylus at the other.

 

There is some good information in this thread, but the word overhang is being misused. This is overhang.

 

Indeed..that is the point I am addressing.....trying to find an accurate way to get that 15mm without a purpose built tool Bob!

 

The advice given in this thread regarding arc protractors and 2-point protractors has been correct, as far as I see. Marantz 45 adapters had overhang marks on them. They would work on other turntables. I once drew the one below on AutoCAD for someone who wanted a replica. The cross was 15 mm from the center and positioned across from the tonearm when the arrow is pointed toward the rear of the turntable.



The reality of it is, there is no true optimum. With a pivot-to-spindle distance of 214 mm, overhang per Stevenson would be 16 mm and Baerwald would be 18 mm. Who's to say the manufacturer's alignment is better than Stevenson and Baerwald? Below is a comparison of the tracking distortion with "Arm1" set at 15 mm overhang and an offset angle of 22 degrees. Lofgren A (Baerwald), Lofgren B, and Stevenson also appear on the comparison. You can see there are times when 15 mm and 22 degrees would be best and times when it would be worst. You pick your poison with any method.



Thanks to vinylengine.com for the calculator.

 

Not to open a can of worms here, but I firmly believe one ought to carefully align the cantilever on the protractor rather than sighting the cartridge body on the grids.

 

Assuming that I correctly understand what you mean by "align the cantilever on the protractor", there's no "can of worms" here; that is the most reliable way to do it, as some cartridges' cantilevers are not aligned properly with respect to the cartridge body.

 

A manufacturer may give an overhang spec, but the truth is that the spec will be different for different alignment methods.

 

Those work quite well but they are expensive if you can find one. Where are you seeing them?

The one on the right is a replica of the original Dennesen Soundtractor. Here is a picture of one in use:



It came in a metal version and a cheaper plastic one for people like me.

 

Right...it's just that some vinyl listeners don't think it's necessary, preferring to just square the cartridge body instead of checking that the stylus tip sits within the indicated points.

 

Oh, I didn't realize that that's what you meant. I was referring to the orientation (right angle or not) of the cantilever with respect to the cartridge body. It's not always perfectly straight.

 

And that's why it's important, of course, there being sample-to-sample variances on how the cantilever is fixed within the cartridge body.

 

saw them on ebay

 

You could make a template like the one I just made. Cut the round hole carefully, place over the center spindle, and point the long line toward the tonearm pivot. Raise the template up near the top of the center spindle and be careful because the cartridge will want to slide off the center spindle when you line the needle up with the cross marks at 15mm.

You will place the cartridge parallel with the head shell.

 

It's threads like this that made me really wish everyone had just agreed to make p-mounts, or some similar plug-and-play self aligning system.

 

forgot it sells for $179 I'm thinking about buying one.

 

I get all this for the most part, and have a laminated grid alignment guide for all the various null point types like Baerwald, Lofgren A or B and Stevenson etc. It also has an overhang grid for setting that first.
That's where it gets murky for me because I have read here and there that use of different null point math may change or require a different overhang ? I only started thinking about this because I read about that aspect and I have a turntable now (Marantz TT15S) that only gives a required distance from stylus tip to a point at the head shell juncture and then a fixed offset procedure (I think).
I got it second hand and I would typically just look up the overhang requirement then move on to Baerwald grid.
I also remember someone at Ava HiFi recommending for a Sony PSX-6 to use a different overhang and Lofgren B for a setup on that TT with the explanation 'to get the needle out there more'
OK so I get that the further distance from the pivot will distort less as it traces, but adhering to certain parameters pertaining to the tonearms resonant limitations is probably something one would want to stick with as opposed to trying to get as much length as possible out of the setup.
So all the overhang specs given per tonearm are based on what null points they use for the alignment they feel is optimum? So then if you can find out what that is yet want to change to a different null math -then what for overhang?
I suppose the arc protractors solve this, and there is the mint protractor that is built to spec per tonearm.
But since I have a grid that allows for any set up -how do I calculate overhang accurately (know which overhang measurement to use)?