Setting "Overhang" Using a "Double Null Point Grid" Type Alignment Gauge

The animated graphic here is taken from the DVD "21st Century Vinyl: Michael Fremer's Practical Guide to Turntable Set-up". The gauge is similar to the kind supplied by Pro-Ject and other turntable manufacturers. It's accuracy is predicated upon the correct pivot-to-spindle for the particular tonearm.

If your turntable is one that's factory supplied with the arm, chances are very good that distance will be correct. If your 'table has the armboard drilled by a dealer or the person from whom you bought the 'table used, measure the distance and be sure it meets spec! You can find out pivot to spindle distances on the the vinyl website.

This gauge sets the "overhang". The "overhang" is the pivot to spindle distance plus the amount the stylus literally "overhangs" beyond the spindle. The arm's "effective length" is the pivot to spindle distance plus the overhang. If your arm allows, you can actually move it so the tube rests on top of the spindle and the distance from there to the stylus tip is the "overhang", which is usually also specified in the arm's specs. It's usually around 16 or 17mm for a 9" tone arm.

The gauge shows the two "null" points where there is zero tracking error (the stylus is tangential to the groove) if you accurately set up the stylus!

To begin, once you've installed the cartridge mid-way in the head shell and set tracking force close to the midrange of the suggested tracking force, put the gauge over the spindle and carefully lower the stylus onto the "X" mark on the gauge (it's hidden under red stylus in the graphic. Rotate the gauge as needed to accomplish this.

Then carefully twist the cartridge in the head shell (loosen the screws slightly if necessary) until the cantilever (red line) is parallel to the hashmarks and the stylus is centered on the "X".

Now carefully lift the stylus using the cueing lever and move the arm to the inner grid (of course you'll have to move rotate the gauge). Align the gauge so the the cantilever is again parallel to the hash marks.

If upon doing so, the stylus tip rests on the "X" you are done! But that almost never happens! Usually it will be in front of or behind the "X". If it's in front of the "X" move the cartridge slightly back in the head shell and start over. If it's behind the "X" move it slightly forward and start over.

Continue doing this until the stylus sits precisely in the "X" and the cantilever when viewed from directly in front, is parallel to the hash marks. Or do it until you want to tear the hair from your head in frustration, at which point just take a break and then resume.

When you are done, re-set your tracking force and then check the two grids again. If it's off, start over! If you didn't have to move the cartridge much in the head shell you should be done!

Stevieray's picture

Talk about pulling the hair from your head!  However, after years of other BS methods, this thing actually makes my setup sound better.

A question for others that have used this gauge:  as you know,m the clear overlay has the grid marks, but the lower plastic card has the stylus alignment point.

'Trouble is, that clear overlay wants to always "bow up", thus making a gap between the cards, resulting in optical "offset" or something of the sort.  'Any way to make that card lay down, short of putting some weights on it -- tiny ones at that; something that would still allow movement of the whole gauge and/or sliding of the overlay.

Whomever called this thing "fiddly" hit the nail on the head.  But as I said, if you've got the patience you will be rewarded!

only analog for me's picture

After a number of years of setting up turntables from the afordable Thorens 166 to the massive Micro Seiki 8000 at a hign end stereo shop in Miami, Florida, with the resulting premature aging, the aforementioned hairlose, and guaranteed entrance into hell many times over with various alignment devices, I always like the concept of the "cart-a-lign" alignment device the most, but not the execution. The primary feature I liked was the mirrored plastic surface which not only protected the stylus from damage like the db, but more importantly, it allowed for parralax free alignment of the cantilever, that is if you had good close-up eyesight. However, the alignment marks were not all the straight and the scoring of the plastic was way to wide with a circular pattern for the thin boron and jeweled cantilevers becoming popular at the time. I later rescored the mirrored plastic with the "new" Stevenson? null points when they were said to provide a lower distortion, can't say as I heard any big difference between the two though. I always hoped someone would come out with a precision made version of the "cart-a-lign", it was my favorite of the alignment devices at the time. I agree with you Mike, the massive turntables like the Micros always had a "solid" sound the lightweight 'tables like the then widely popular Linn Sondek Lp 12 could never provide, ever noticed how damn many "improvements" by Linn and others have to be added to get the "best" sound out of the LP 12, where the massive Micros and other massive 'tables deliver? I'm sure some "linn" devotee will slash my comments... However, I can't say I completely agree with the 92 degree set-and-forget-for-ever-record advice. I remember my Winn Jewel cartridge sounding good but nothing special until I moved it that last nth degree up or down where the sound would suddenly come alive, and it wasn't subtle, I ended up marking all my albums for the exact readout of my specially mounted swiss made dial indicator, I really hated having to realign for various records, and I wouldn't have done it if I didn't hear a big difference, I was 23 y.o. at the time so my hearing was very good. I have thought of building another "table" and I really hope the 92 degrees is the end setting, I'm too old to screw with stereo equipment like I use to, I want to set back listen and relax.................

AndersKH's picture

Funny that you say that that "boomerang" is your favorite as it is my favorite too.

only analog for me's picture

I'm surprised the box doesn't allow for spelling errors to be shown, I'm sure I made a few...

actarus71's picture

my AVID Rega alignement tool. I would love to try the WallyTractor but I'm not paying $150 for a protractor...

jellis's picture

Hello "only analog for me",

I have been using a "cart-a-lign" since 1980 or 81 it was cutting edge at that time.

Made a hobby out of setting up several friends tables there is nothing like the look on someone's face when they hear their own system post alignment.

If memory serves I had to order it from the company out of the east [New York ?] at a cost of $35.

only analog for me's picture

Hi jellis, I bought my "cart-a-lign" around the same time as you. At that time I was working at "Audio by Caruso" in the Kendall area, south of Miami, I still have mine and use it when needed. I've thought of building a premium version, but the cost to manufacture has always killed any further interest. I've always felt that hi quality audio should be affordable, although I do love building and reading about "damn-the-torpedos" approach by various manufacturers. I too have always tried to push the envelope with the best quality parts, and being a picky-ass certainly doesn't help, unfortunately, that has almost always pushed the price up and out of reach for most audiophiles, I seem to have expensive tastes... in everything, lol, $35.00 is a distant memory. Happy Holidays to all!

praxiteles's picture

I don't think you can get a really correct overhang by following the manufacturing specs. you have to find out by testing. I don't think any of the protractors are much good either because there are so many different carts on the market. Here are my findings.