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LP-12 Naim Aro Owners Please Read

Discussion in 'audio' started by LinnAroMan, Nov 21, 2009.

  1. Nik

    Nik pfm Member

    Depends on what alignment you want. Stephenson, Baerwald, and Löfgren give different answers and these are just suggested alignments. Where do you want the null points to be?
     
  2. John

    John pfm Member

    Thanks,

    Just to compare apples to apples, what would be the associated pivot to spindle distances with 7mm and then can you do the same for 10mm?
     
  3. Nik

    Nik pfm Member

    Parallel trackers have their own problems. If it's active, it needs to move out of alignment before the servo can react to correct the alignment, and how good is the structural integrity at the servo end? How good is the tracking error in practice?

    If it's passive, the levelling has to be exact, and the stylus has to drive the whole moving mass in the horizontal plane. How can the cartridge's suspension have anything like the right compliance for that and also work properly in the vertical plane?
     
  4. andyr

    andyr Registered User

    That is truly a staggeringly smug statement, teme. :p Let me just "return your serve" ... if it sounds better, it is better! :D

    A couple of Sundays ago, a friend of mine came over to listen; he's a guitarist and loves "Friday Night in San Francisco". I put it on and when the first track was finished he said "I must've played that over 500 times (CD) and I heard things then, that I have never heard before".

    So, even if you claim it must be a bodged, out-of-tune mess, my LP12 sounds great. :)

    So you are one of these people who say putting a Keel on an LP12 "takes away the LP12 character"? (Because it certainly wasn't thought of when Ivor developed the LP12.)

    You must also say that the Radikal must be a bad idea, because Linn always promoted their AC motor (and controllers) against OL's DC drive?

    My opinion is that things can be done to an old stock LP12 which improve upon what it was before. A Keel is one - as is the Rubikon - as is a L2 over a L1 (over a Valhalla).

    I could go on about the arm and the plinth but I won't! As you said (Linn said) "if it sounds better, it is better"! :D

    Regards,

    Andy
     
  5. Nik

    Nik pfm Member

    7 mm: effective length 228.15, Baerwald 209.94, Löfgren B 209.42
    10 mm: effective length 230.84, Baerwald 212.86, Löfgren B 212.35

    I'm using Naim's offset angle of 24° for all these. This can only be correct at the stylus tip for one effective length when you have holes, not slots, so there must be a small error. I'll see if I can work out how much.

    The Baerwald and Löfgren figures are from the Vinyl Engine Calculator BTW.
     
  6. Teme

    Teme Retrophile

    So we actually agree on something? I.e. it is not about being optimal by some measure (that can almost always be countered by another measure) but rather about sounding great to our respective ears?

    I'd appreciate if you did not try and put words into my mouth as this is not my view, i.e. I am not "one of those people" (whoever they may be).

    Indeed. And if I did not think so, why would I have a Keel, a Radikal, an Aro and a Dynavector on my deck?

    Br,
    Teme
     
  7. andyr

    andyr Registered User

    We agree on several things, teme - like, an LP12 is a very worthwhile record spinner, for instance. :)

    My only point in all of this is that IMO there is some conflict happening, when one uses an Aro with a cartridge having a different bolt-hole-to-stylus distance than what it was carefully designed for. With a DV cartridge, you have done the best you can but you are unable to optimise that combination, due to the lack of headshell slots to compensate for the different b-h-t-s distance (and the different offset angle associated with this).

    Me - I would find this a nagging problem - no matter how good it sounded. :) That's why the Aro wasn't on my shopping list when I replaced the DV505 arm that the dealer sold with my LP12 in 1978, about 8 years ago.

    With my G2.2, I can optimise with whatever cartridge I choose to use. The Benz LP and before that, a Benz Ruby2, are what I have used; next cartridge upgrade will be to a Benz LP S, next time I need a retip. :)

    Regards,

    Andy
     
  8. John

    John pfm Member

    Thanks Nik!

    7 mm: effective length 228.15, Baerwald 209.94, Löfgren B 209.42
    8.5mm: effective length 229.49, Baerwald 211.4, Löfgren B 210.9
    10 mm: effective length 230.84, Baerwald 212.86, Löfgren B 212.35

    Assuming all these measurements are correct, it looks like the Aro/Keel is more optimized for a 8.5mm cartridge like Teme suggested.

    James, looks like the GS would suit the newer Lyra quite nicely.

    Makes you wonder what the pivot to third bolt measurement on the Aro vs. Ekos is?
     
  9. James

    James Lord of the Erg\o/s

    This is brilliant. I was contemplating the DVXX2 (8.5mm) and almost bought a lightly used Helikon SL (7.8mm) amidst the confusion. Now I see the path is clear for a 9.5mm Kleos or Delos to get near perfect Baerwald alignment.

    Thanks Nik and John.
     
  10. John

    John pfm Member

    The specs drawn up by Nik is finally adding some clarity to the discussion. The thing that is interesting to me is that I always thought the Aro was optimized for Linn cartridges. The 7mm to 10mm specification found in the Aro owner's manual now makes sense when put with a 211mm +/- 1.5mm pivot to spindle spec.
     
  11. James

    James Lord of the Erg\o/s

    This makes the 7mm Linn carts plainly wrong with a 211mm rigid Keel. Who would have thought ...

    James :D
     
  12. John

    John pfm Member

    Paul,

    How do you account for the Troika sized cartridge when entering numbers into the calculator?
     
  13. Paul R

    Paul R pfm Member

  14. John

    John pfm Member

    How do you get the implication of the Troika based on the bolt measurement from the drawings and Nik's calculations. The 7mm to 10mm specs in the Naim Aro owner's manual makes it appear that 8.5mm would be optimal in a fixed chassis.
     
  15. Paul R

    Paul R pfm Member

    I don't. The Naim specs are 229/18/24. Are you suggesting that the Troika in an ARO doesn't meet these specs? This is independent of whether you mount the arm 221mm from the spindle.

    Paul
     
  16. John

    John pfm Member

    I'm trying to arrive at what the optimal cartridge bolt to stylus measurement is based on the fixed Aro headshell bolts and fixed arm pivot that a Keel sub-chassis presents. Seems like 8.5mm to me.
     
  17. Nik

    Nik pfm Member

    Please don't place too much faith in my figures. There seemed to be some doubt about what the Aro spec actually was and I thought the pivot-to-cartridge bolt distance would help. It's easy to measure on the real thing and some trig would do the rest. The geometry/trig turned out to be trickier than I thought but I think it's right.

    It would make sense that the Aro's geometry is the same as the Ekos's and I think it is, bearing in mind measurement tolerances and rounding:-
    Ekos: offset 24°, effective length 229 mm, pivot-spindle 211.

    The "other" Aro spec is
    Aro: offset 24°, effective length 230.5, pivot-spindle 212.5.
    Taking that effective length we get
    effective length 230.5, Baerwald 212.49, Löfgren B 211.98
    but the offset should be 23.9°. I think this requires a stylus-to-cartridge bolt distance of 9.6 mm.

    Might as well put it all together:-
    7 mm: effective length 228.15, Baerwald 209.94, Löfgren B 209.42, offset 24.2
    8 mm: effective length 229.04, Baerwald 210.91, Löfgren B 210.39, offset 24.1
    8.5mm: effective length 229.49, Baerwald 211.39, Löfgren B 210.88, offset 24.0
    9.6 mm: effective length 230.5, Baerwald 212.49, Löfgren B 211.98, offset 23.9
    10 mm: effective length 230.84, Baerwald 212.86, Löfgren B 212.35, offset 23.9
     
  18. Teme

    Teme Retrophile

    This is really good stuff. However, there is still one thing that bothers me. I wonder if the below is the right measure to use in the calculation:

    Or should we rather use the distance from the pivot to the midpoint between the two front bolts (and the offset and the cart stylus tip to mount hole distance as before)? This distance would be slightly less than the 224.5mm used for the above calculations.

    If yes, I assume that the distance between the front bolts is somewhere around 12-13mm (the Dynavector drawings show 12.7mm for example). The midpoint naturally being half of that. And I guess the offset angle also has to be taken into account here before deducting from the 224.5mm measurement? Or am I off the mark?

    Br,
    Teme
     
  19. Nik

    Nik pfm Member

    Excellent point. That is the measurement I originally asked for but when you think about it, measuring to the centre of one bolt hole is easier and takes another potential source of error out of things. You wouldn't need to deduct from the 224.5 figure if you measured to the midpoint, and when it comes to the geometry/trig calcs, it makes no difference as long as we know which point we're using.

    The distance between the 2 "normal" bolt holes was standardised at 1/2" ages ago. This is 12.7 mm and I used 1/2 that, 6.35, in my calcs as the distance between the outer bolt hole and the point from which the mount-to-stylus distance is measured.
     
  20. Teme

    Teme Retrophile

    ^Ok. Great. My hat off to you for doing these calculations!

    Br,
    Teme
     

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