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Stevenson Alignment not working - what am I doing wrong?

Discussion in 'Turntables' started by Kencat, Jan 30, 2007.

  1. Kencat

    Kencat Super Member

    Messages:
    1,657
    Location:
    Peterborough, Ontario
    Need some advice folks. I've been spending lots of time with the Vinylengine Stevenson protractor (after messing with the Baerwald and Loefgren until reading the Stevenson is typical on the Japanese TT's). I've tried on two TT's - a Technics SL-20 and a Realistic R-8010, with different cartridges and two different headshells.

    I keep getting though, where the cartridge is as far forward in the slots as possible, and severely cocked counterclockwise (from top looking down), but still not quite lined up. It looks like the cartridge still needs to go further forward but I'm out of slot length.

    Checking with my Technics overhang gage, the needle tip is beyond the 52 mm specified.

    I have verified the line length on the printed protractor.

    Any ideas on what I may be doing wrong, or anyone else experienced this?
     

    Attached Files:

  2. Mark B

    Mark B Yamaha Fan Subscriber

    Messages:
    5,017
    Location:
    usa
    How you are setting up the protractor?

    Place your protractor over the spindle and then rotate the protractor / platter until you can place the stylus on the alignment point on the outer grid. Align the cartridge so it is parallel to the grid lines. Then rotate the protractor / platter until you can place the stylus on the alignment point on the inner grid. Align the cartridge so it is parallel to the grid lines. Then check the alignment again on the outer grid, and make any necessary final adjustments.
     
  3. ozmoid

    ozmoid Lunatic Member

    Messages:
    13,422
    Ken, try setting the overhang right and just line the cart up square with the headshell. On the Japanese S-arms, that should give you a near perfect alignment if I understand this correctly.

    The protractor can be frustrating.
     
  4. Kencat

    Kencat Super Member

    Messages:
    1,657
    Location:
    Peterborough, Ontario
    There is no line to sight to the tonearm pivot point on this Stevenson printout. I've seen the mirrored protractor that you are probably referring to (turntable basics?). I've been using an iterative approach as explained here - http://www.audioasylum.com/audio/vinyl/messages/51464.html

    I think in the end, the same outcome is achieved but with a bit more "steps". There will be a certain overhang and cartridge twist that fits both grids.

    It's just that the iterative steps drives the cartridge out of bounds so to speak. :sigh:
     
  5. hakaplan

    hakaplan Needs professional help

    Messages:
    10,727
    Location:
    Philadelphia, PA
    Ken, I agree with Ozmoid. Use the overhang gauge on the Technics. Are you sure the protractor was printed out to correct scale?

    Since all Japanese turntables were designed so that the cartridge is parallel with the headshell, the easiest way to use the Stevenson protractor is to use a single point, and align the cart parallel and so the stylus is on that point. When you then move the arm over to the other point, it should be lined up or very close. You'll probably have to use that method for the Realistic unless you have a gauge for it or know the length measurement.

    PS. Your link is the correct way to use a protractor, but you don't have to go through all that for this--the Japanese mfrs specifically wanted it to be easy for you.
     
  6. Kencat

    Kencat Super Member

    Messages:
    1,657
    Location:
    Peterborough, Ontario
    Aye to your last statement.:D

    But if the protractor is "correct", and the overhang gage setting gives a way off Stevenson alignment........which is the right one ?

    I have to say though that the "nearly there" protractor setting sounds pretty good and there are no tracking issues.

    I'll have to try the overhang gage and listen to it I guess. Sure would like the 2 pt. grid to work though, as this makes sense.

    I'm thinking of elongating the slots in one of the headshells and maybe even get the Baerwald to work out.
     
  7. hakaplan

    hakaplan Needs professional help

    Messages:
    10,727
    Location:
    Philadelphia, PA
    Also, that headshell is too short for the Technics. You will have to elongate the slots or get either a Technics or Stanton or one of their lookalikes.
     
  8. Kencat

    Kencat Super Member

    Messages:
    1,657
    Location:
    Peterborough, Ontario

    Hey there Hakaplan.

    The cross-page line was very close to the specified length on the printed protractor. I suppose the up-down direction could be suspect - too bad there is not a reference line in that direction.

    No gage or clue as to what the overhang is on the Realistic (not a bad little TT BTW with a nice AKG P7E cart). The pics are from a cart done on the Realistic.

    If the overhang gage setting does not match the protractor I'll be worrying about which is right. :scratch2: Just the kind of crazy guy I am. Oh well :D
     
  9. Kencat

    Kencat Super Member

    Messages:
    1,657
    Location:
    Peterborough, Ontario
    Actually, it is OK. I just found (well my wife did) the overhang gage tonight, and put it on the same headshell setup as in the pics. No problem pulling the cart back so the stylus tip lines up.

    The tip is currently about 3-5 mm forward of the overhang gage.

    I should be "good to go".
     
  10. Mark B

    Mark B Yamaha Fan Subscriber

    Messages:
    5,017
    Location:
    usa
    Sorry about that Kencat - when I posted that I didn't remember that the Stevenson protractor doesn't have a sighting line. I edited my original post, but too late.
     
  11. Kencat

    Kencat Super Member

    Messages:
    1,657
    Location:
    Peterborough, Ontario
    Hey, no problem Mark. I appreciate the responses. They all end up helping in some way :yes:
     
  12. vinylengine

    vinylengine AK Old Timer

    Messages:
    352
    Hi,
    There's some (understandable) confusion here regarding alignment :scratch2:

    If you have an overhang gauge and know the recommended overhang for your turntable, you can use this to set the manufacturers original alignment.

    If you don't know the overhang for your table then you need to use a two-point protractor, and align to both points. This may require some offsetting of the cartridge in the headshell if the manufacturers chosen alignment is different to that of the protractor.

    FWIW 99% of commercial aftermarket protractors (Altai, HFN, Turntable Basics, Ortofon etc) use Baerwald alignment which may be difficult to align to on many older arms as the headshells may not have enough room in the slots.

    If you set alignment using an overhang gauge, don't be surprised if the cartridge doesn't line up with a Baerwald/Loefgren/Stevenson protractor, manufacturers use varying null points/alignment. This is very common - you should only ever double check alignment with a protractor that uses the same null points. If you check out the null points in my tonearm database you'll see that very few arms align perfectly to Stevenson or Baerwald null points with stock overhang. However, if you stick to a protractor whose null points are closest to those chosen by the manufacturer you shouldn't have too much trouble aligning at both points.

    PS A 'quick and dirty' way to align a cartridge how the manufacturer intended is to make it parallel to the sides of the headshell with the mounting bolts central in the slots. This will often give the correct overhang straight off - but always check :thmbsp:
     
  13. Kencat

    Kencat Super Member

    Messages:
    1,657
    Location:
    Peterborough, Ontario
    Thanks for that great explanation JaS. It helps my angst a lot.

    The reason I made that statement about which method would be "right" was because it was being stated here that the Japanese S-arms were of Stevenson alignment, including the Technics. Therefore, if one used the Technics overhang gauge (on a Technics of course), the Stevenson 2 pt. protractor should also line up bang on.

    I haven't tried that yet, but based on where the cartridge ended up using the protractor, I'm pretty sure it will not match the overhang gauge. I will maybe try it later tonight for fun and enlightenment (although I'm not going to use the Technics because the tonearm bearings are kind of stiff - the arm doesn't bob a few times when trying to balance it).

    I understand then, from what you wrote, is that the various Japanese (and others) S-arm manufacturers did not necessarily adhere to a strict "Stevenson" geometry standard, so if the cartridge is going cockeyed trying to get the Stevenson 2 pt. to work, I should not worry. :D

    Does it make sense though that I'm running out of headshell slot length for the Stevenson? From what I've read this would be expected for the Baerwald and Loefgren Alignments, but the Stevenson should be closer to the Japanese S-arms geometry.....or maybe not ???
     
  14. trinescope

    trinescope Member

    Messages:
    83
    Location:
    Fort Worth, TX
    What I found when I checked a SL-1200 arm aligned using the Technics gauge was that the Stevenson alignment was VERY close (but not perfect), so a Stevenson alignment should be possible in the absence of the manufacturer's gauge without resorting to any modification of the headshell.
     
  15. hakaplan

    hakaplan Needs professional help

    Messages:
    10,727
    Location:
    Philadelphia, PA
    Agreed. It will be closer to Stevenson than either of the other two.
     
  16. Kencat

    Kencat Super Member

    Messages:
    1,657
    Location:
    Peterborough, Ontario
    you gents are correct.

    Erich, Howard,

    Well, I did the experiment tonight. Set up the Technics headshell with a new AKG (NOS) cart to the overhang gage. Installed the headshell on the Technics and checked it to the Stevenson protractor. Not quite perfect but damn close. The inside grid was 99.5% though :thmbsp: You guys are right on.

    Now, what's interesting, is that when I put this technics gage set-up headshell on the Realistic TT, it is quite a bit off. Both grids show that the cart needs to twist clockwise or go shorter....hmmm, why was I going longer and twisting before???? I gotta retry the Stevenson protractor on the Realistic again. I'll get this beat yet.

    There is no overhang gage with the Realistic.

    I appreciate all the help on this. Once mastered, this will be good skills to have as I move up the TT ladder......now for all those other adjustments :D
     
  17. ozmoid

    ozmoid Lunatic Member

    Messages:
    13,422
    Between the two tables, there is likely a difference in arm length and offset (pivot > spindle) distance. That'll throw your cart alignment from another table right out the door...
     
  18. hakaplan

    hakaplan Needs professional help

    Messages:
    10,727
    Location:
    Philadelphia, PA
    Ozmoid is right, you can only use that overhang gauge (52mm) on the Technics. I remeasured myself and found that with the cartridge parallel to the headshell, the Technics gauge puts the stylus tip 2mm short of both of the Stevenson null points. The other protractors were farther off.

    Most of the other Japanese tables have shorter stylus to end-of-headshell measurements and you've discovered that the Realistic does, as well. Having measured myself I know that Pioneer, Sony, JVC, and Hitachi all coincide exactly with Stevenson. My guess is that the Realistic will, too.
     
  19. vinylengine

    vinylengine AK Old Timer

    Messages:
    352
    As Hakaplan says, most Japanese arms tend to be very close to Stevenson alignment - but they do vary!

    Historically, Japanese arms weren't strictly speaking Stevenson, rather they where designed for DIN (JIS) standard pressings which have a maximum outer radius of 146.05mm and minimum inner radius of 57.5mm. US/European arms tend to be designed for IEC radii of 146.05mm and 60.325mm. Stevenson alignment is biased towards low distortion on the inner grooves, hence the similarity with the alignment of many Japanese arms which are expecting to read grooves closer to the label.

    It's also worth noting that early SME arms had Stevenson alignment, but later models went over to Baerwald which is more suitable to real life pressings and has lower overall distortion.

    Unusually, when Rega designed their RB250/300 arms they copied the geometry from the Japanese built arms they had used previously, so 25 years on their current top of the range RB700 and RB1000 arms still have an alignment better suited to early Japanese pressings, or lower inner groove distortion (depending on how you look at it!) :scratch2:
     

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