Alignment with a Technics overhang gauge

Discussion in 'Audio Hardware' started by 33andathird, Sep 28, 2020.

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  1. 33andathird

    33andathird keep em spinning Thread Starter

    Location:
    ireland
    I have a Technics sl1500c and an ATVM95ml cartridge. When i purchased the cart, I aligned it with a Stevenson protractor from Vinyl Engine and got it fairly good, however the cartridge is skewed very slightly in the headshell (is this normal for an S shaped tonearm)?
    Anyway I've been getting a bit of Inner Groove Distortion/groove wear (cant tell) on some albums and thought what the heck, I'll try this overhang gauge contraption and see if it makes a difference, out of curiosity.
    So if I'm right- I align the stylus with the end of the gauge (going to be very difficult with a ML stylus lol), and make sure the cartridge is square in the headshell. Am I done after this? If so, it would be a hell of a lot easier than the protractor (I have to resort to the 'pencil lead' trick as the new AT carts are not square). The cantilever looks to be in line, however the stylus, when viewed from the side, seems to be ever so slightly pointed downward a bit. Is this normal? I'm probably just being over the top. It's probably designed to 'level out' when in contact with a record.
    Appreciate the help.
     
  2. patient_ot

    patient_ot Senior Member

    Location:
    USA
    Pics would help.

    With Stevenson alignment OR Technics alignment, the cart should be square in the headshell. NOT twisted toward or away from the spindle.
     
    33andathird likes this.
  3. 33andathird

    33andathird keep em spinning Thread Starter

    Location:
    ireland
    These curved carts are the BANE of my life right now. They'd be so much easier to get square if they were....square. They look cool, but I'd happily have the ugliest looking cart in the world if it meant easier alignment.
    I hope I didn't damage my records with the cart having been skewed...I didn't hear distortion on my LPS (bar a few with groove wear)
     
  4. 33andathird

    33andathird keep em spinning Thread Starter

    Location:
    ireland
    My eye is sore from all the squiniting and eyeballing, lol. I've successfully set the overhang with the gauge, I think. Stuck on a groove-worn album and unfortunately it's the same.
    Can I confirm the Technics overhang with a Stevenson protractor?
     
  5. patient_ot

    patient_ot Senior Member

    Location:
    USA
    Nope. The Technics overhang is proprietary. It's based on Stevenson but not the same. And even Stevenson alignments will vary a little, depending on the groove spacing standard used.
     
  6. Echo's Answer

    Echo's Answer Forum Resident

    Location:
    Chicago, IL
    Go buy some magnifying reader glasses from Walgreens. Makes it easier
     
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  7. Thorensman

    Thorensman Forum Resident

    Use the recommended Technics
    Tool

    I set up a SL1200 a while back

    Using my usual gauges its obvious
    That something was amiss.
    The setting was a measurement
    From rear of headshell to back of cartridge.
    It worked!
    Checking my results with my regular gauges made no sense at all.
    It worked beautifully
     
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  8. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    No, only with the Technics alignment and when using the Technics overhang gauge will it be straight and will you be aiming to get it straight.
    Technics is Stevenson, slightly modified for even better inner groove tracking.

    Alignment is setting the stylus tangent to the groove at both inner and outer alignment nulls, by setting both cartridge rotation and slot position. The Technics alignment system has never had the full specs published as far as I know, only inferred from research, so you can't verify at the nulls.

    Verify that the tonearm is perfectly horizontal when set in the groove (tonearm base height), and that the tracking weight is correct (to not throw off VTA by crushing the suspension, nor to allow grooves to lose contact). Then you can work with antiskate, which should be dialed near the tracking weight.


    Bayonet headshells also have a bit of play in the "pin"; there's usually about one degree of rotation depending on how you hold and twist it when you cinch the clamp up. Although you can eyeball it, this really can't be set for the variances found in cartridge and stylus manufacture except by using test records and instrumentation/analysis, as you are adjusting the azimuth to minimize crosstalk. Really bad azimuth, and you have to adjust/modify the tonearm-to-bayonet mounting.
     
  9. 33andathird

    33andathird keep em spinning Thread Starter

    Location:
    ireland
    Here are some photos. Sorry about the links but its the only way I can add them. Interesting about the difference, I could swear I heard people talking about how they always double check with a Stevenson. Anyway, checked it, and it's not the same.

    Squaring the cart, I go by the bevelled edge of the front and eyeball the corners- https://photos.app.goo.gl/QonHL9KqohF7eyTo9
    https://photos.app.goo.gl/oZCy96VzwvQXeo3J8

    Setting the overhang: https://photos.app.goo.gl/JmSFnBZq2QZcS2E8A
    https://photos.app.goo.gl/Zx1y1r2EjqvRq38G7
    https://photos.app.goo.gl/GFgy8f5s5iyyW88J7

    Really appreciate the help, you really live up to your namesake dealing with the likes of me!!
     
    ralphb97 likes this.
  10. 33andathird

    33andathird keep em spinning Thread Starter

    Location:
    ireland
    Yes, it's the official gauge.
     
  11. patient_ot

    patient_ot Senior Member

    Location:
    USA
    Hard to tell from those pics, but in the first set of pics it looks like the cart is pointing a hair to the left rather than being centered. Technically, what we really want to align is the stylus, not the cart body. AT quality control is usually pretty good though. What I would do is a get a razor blade or some kind of small straight edge to verify the cart is straight in the headshell, then look at the stylus and make sure that is where it needs to be on the tip of the gauge.

    NOTE: it looks like your gauge might be warped. Unfortunately a bunch of them are. That's going to make things more difficult for you.
     
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  12. mkane

    mkane Strictly Analog

    Location:
    Auburn CA
    Print out a protractor and use that.
     
    Lownote30 likes this.
  13. 33andathird

    33andathird keep em spinning Thread Starter

    Location:
    ireland
    Have you even read the thread mate
     
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  14. Dr. J.

    Dr. J. Music is in my soul

    Location:
    Memphis, TN
    FWIW, I have the same cart and always use the overhang gauge to get my alignment right. But I do it with the gauge standing up on a tall chest of drawers so I can get my eye level with the edge of the gauge. That way also I am sighting the stylus tip alone, so I am not thrown off by the cantilever and cartridge body.
     
  15. Wayne Nielson

    Wayne Nielson Forum Resident

    Location:
    My House
    The Technics arm is 215 mm from pivot to spindle. The overhang is 15mm. It is designed around a Stevenson "DIN" alignment, it is a Stevenson DIN alignment.

    Actual mathematical numbers are:

    Overhang: 14.929
    Offset angle: 22.120
    Inner null radius: 57.500°
    Outer null radius 115.522°
    Effective arm length: 229.929mm
     
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  16. 33andathird

    33andathird keep em spinning Thread Starter

    Location:
    ireland
    Thanks, how the hell do you stop the cart from moving when tightening the screws lol
     
  17. 33andathird

    33andathird keep em spinning Thread Starter

    Location:
    ireland
    Does anyone think that having had my cartridge slightly skewed in the headshell before this would have caused wear? This was done with a protractor and if I can recall was not perfect but almost.
     
  18. 33andathird

    33andathird keep em spinning Thread Starter

    Location:
    ireland
    Do you double check it with anything after?
     
  19. Dr. J.

    Dr. J. Music is in my soul

    Location:
    Memphis, TN
    Nope, not usually (double checked once maybe); maybe I should but never have had a problem. The VM95ml is so quiet in the groove and I get zero IGD or mistracking that I must be spot on.
     
  20. shnaggletooth

    shnaggletooth Senior Member

    Location:
    NJ
    Having similar questions. The only alignment that matters is the stylus tip to the edge of the tool, right? If the tip appears to be "off-center" looking straight-down from the front of the cart (at an angle), that's ok, as long as the tip lines up to the tool?

    (Ok, you might have answered my question, already, Dr. J)

     
  21. Dr. J.

    Dr. J. Music is in my soul

    Location:
    Memphis, TN
    I would say no. I mean the stylus tip should be centered in the middle of the gauge where mine, at least, has a slight groove. I wouldn't be comfortable with it to the right or left of that mark too much. Maybe not the end of the world for a conical or elliptical profile but certainly not a shibata or mircoline. Something like this:

    [​IMG]
     
    Last edited: Sep 28, 2020
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  22. shnaggletooth

    shnaggletooth Senior Member

    Location:
    NJ
    Both my carts have stylus tips that don't seem to be square with the cart bodies (Stanton 680EL and Shure M91ED), which makes everything a pain in the butt. But then, both are ellipticals. Am thinking of upgrading to the VM95ml (at least, for my best records), so total alignment will have to be a consideration.
     
  23. mkane

    mkane Strictly Analog

    Location:
    Auburn CA
    I have. your gauge is warped
     
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  24. mkane

    mkane Strictly Analog

    Location:
    Auburn CA
    Keep one side snug after you get the overhang close. Then tweek, get it right, snug the other and check again.
     
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  25. mkane

    mkane Strictly Analog

    Location:
    Auburn CA
    Using the gauge that comes with the deck assumes your cartridge is perfect.
     
    Lownote30 likes this.
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