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Disappointing experiences with a Dynavector XX-2 mkII, Linn Kore, and Ekos 2

Discussion in 'audio' started by hifiaf, Apr 23, 2020.

  1. Mr Pig

    Mr Pig ^'- -'^

    I'll be interested to hear what they say. I can't see how that can be damage. I think it left the factory like that.
     
  2. 2ManyBoxes

    2ManyBoxes pfm Member

    It's a Kore not a Keel. They are not CNC'd from a solid billet of aluminium, as the OP says they are glued and screwed together. I would think that that makes them more susceptible to manufacturing faults.

    However, as the OP is not the original owner and so there is a gap in the history of the item, Linn would be perfectly within their rights to say that someone has damaged it by dropping something heavy like a power amp on it. I suspect that that's what happened, the person you bought it from probably thought it looked all right after whatever the accident was and sold it anyway. It isn't obviously bent after all.

    It's a risk you take when buying second-hand, you've been unlucky. You can only stick it in a vice and hit it with a (plastic) hammer until it's sort of straight :) Maybe incorporate it into one of your bike frames, although it'd have to be for someone pretty small :D

    I bought a second-hand pair of SBLs once that looked fine but needed a lot doing to them because the person I bought them from had probably stored them in a garage or somewhere else damp and with spiders. Unfortunately I suspect that your problem may not be so easily fixed...
     
  3. 2ManyBoxes

    2ManyBoxes pfm Member

    So how come the same arm and cartridge works fine on another sub-chassis? The only time the OP gets the problem is when the Kore is fitted.
     
  4. hifiaf

    hifiaf pfm Member

    I've made a video showing what's happening. I found a disc in my collection with a HUGE runout area, a Roxy Music single. I set the VTF to 2.0, verified with two gauges. With anti-skate at 1.7-1.8, the arm flies inward. With anti-skate set to maximum, it's clearly exerting a lot of inward force, actually -- it pushes inward with the arm sitting on the rest, so against considerable resistance. But still, the arm flies inward. I can't explain all this conflicting data — a seemingly strong anti-skate spring, a cartridge that flies inward from near the outside of the disc. Perhaps someone else can!



    (I suppose one explanation is that the Soundsmith test makes no sense, and that arms should fly inward even with proper anti-skate set!)
     
  5. hifiaf

    hifiaf pfm Member

    I'm still getting the same problem with the (flat) Mober subchassis in place. Music is sounding a little better with the Mober than the Kore, but the main problem is independent of the subchassis.
     
  6. YNWOAN

    YNWOAN 100% Analogue

    Hmm...dunno, very weird. In the vid though, that's all run-out groove (absolutely massive though) and the stylus should lock onto that groove, not jump across the groove like that! There is definitely a stylus on that cantilever isn't there - or some very stubborn gunge welded to the back of the stylus?
     
    torstoi likes this.
  7. YNWOAN

    YNWOAN 100% Analogue

    Hmm.. good point - is that what's happening then?* If the OP has a small bubble level he should compare it on the headshell and the platter - but something would have to be massively misaligned to be doing this.

    * Oh, apparently you are mistaken (which is good because otherwise something really weird is happening).
     
  8. sq225917

    sq225917 Bit of this, bit of that

    That's weird, the fact it slips on the rest is crazy, never even seen that.
     
    torstoi likes this.
  9. hifiaf

    hifiaf pfm Member

    Yes, definitely a stylus on there. I've looked at it with a 20x loupe and it's absolutely clean. It tracks grooves when you put them straight in without problem (aside from a bit of sibilance, not much outside the norm). Indeed, it tracks that (massive) runout just fine coming out of the song. But inserted in between, it flies off at top speed, as you can see.
     
  10. YNWOAN

    YNWOAN 100% Analogue

    Yes, indeed! As you say in the vid, the behaviour on the rest would suggest the anti-skate mechanism is working fine.
     
  11. YNWOAN

    YNWOAN 100% Analogue

    Yeah, I’ve seen that before - usually giving the rubber on the lift/lower support a rub with some alcohol stops it.
     
  12. Vimtokid

    Vimtokid pfm Member

    Arm is definitely clearing the rest, isn't it?
     
  13. hifiaf

    hifiaf pfm Member

    Yes, definitely clearing the rest.
     
  14. torstoi

    torstoi pfm Member

    With no tracking force and no anti skate & in balanced state,
    is the arm swinging smoothly up and down when gently tipped at ?
    A careful blow (ideally with the needle protection on) should send it
    swinging in wave-like movement over across the platter.
    Up and down movement should be very sensible & when perfectly balanced,
    should end in ~horizontal position.
    Mine randomly just froze in any higher or lower position during this test once
    & then I knew my bearings had to be looked over by J7.

    I'm really curious what's going on with your deck now.
    In worst case the bearings are not 100% anymore, skate is also a bit off or not reliable at all -no idea
    and it could also be the suspension of your DV received some damage in the past.
    Would be extremely bad luck, but not impossible.
    Would track like a pig and near impossible to get on song in said combination.

    I hope the DV is ok, but the fact you cannot even beat an Adikt is a bit scaring.

    That said, why not get some brand new & relatively cheap AT95E as a guinea pig
    and try if you can get that to track right & perform @ ~1,7gr?

    If you get that to play music as you'd roughly expect it to,
    would rather point towards the DV having some issue perhaps.
     
  15. hifiaf

    hifiaf pfm Member

    Just had a great chat with J7 about this. His thoughts:

    1) He thinks the Soundsmith test is flawed. He says that a sharp tip like the one on the XX-2 is going to actually cut into the space between* the run-out grooves, creating more friction than even loads of anti-skate. So that's why it's flying inward: the test is flawed.

    2) He wonders if the issue isn't the compliance of the XX-2 -- it seems to him too stiff, like it's jumping out of the groove, bouncing right off the surface of the disc because it's so stiff. It does seem pretty stiff to me. It settles a little when it's put on a record, but the sagging is minimal. He thought maybe it had been badly retipped with the suspension set wrong. Or it could have left the factory that way.

    3) He thought it could be the Ekos bearings, but probably not. I agree: I've done all the usual bearing tests, including the swing test, and they seem fine.

    Speaking of retipping, he told me to beware my other MC cart, an Expert Stylus retipped Troika that I haven't tried yet, and which has seen zero hours of use since retipping. A topic for another day.

    But for now: J7 thinks the arm seems fine, the anti-skate dial seems fine. The thing to check out is the cartridge compliance. I'll see if I can get a Dynavector dealer around here to have a look...

    * Unintentionally, another Roxy Music reference.
     
    Mr Pig and torstoi like this.
  16. hifiaf

    hifiaf pfm Member

    Here are two looks at the XX-2 dropping into a groove. Any thoughts on compliance/stiffness here (if you can even tell from two shaky videos)?



     
  17. Dan K

    Dan K pfm Member

    I'm sticking with my original diagnosis. That looks to have 'bananaed" because it was cut from cheap rolled stock and then not heat treated/ stress relieved. It should have been machined from cast tooling plate.

    Linn might be interested as this may have turned up before. They should be able to pull the drawing + trace the machine shop and material order. Possible they fecked up and spec'd something like generic '6082' instead of '6000 series CAST + annealed tool plate'. Either that or the machine shop did them over. Will be interesting to get their response

    http://www.metalweb.co.uk/product/aluminium/aluminium-rolled-plate-sheet/

    http://www.metalweb.co.uk/product/aluminium/tooling-plate/

    Perhaps too much geekery
     
    YNWOAN and hifiaf like this.
  18. forester

    forester pfm Member

    There's more to my Kore than I thought (can't see the underneath).
     
  19. sq225917

    sq225917 Bit of this, bit of that

    I dont know the Linn antiskate mech at all. So my suggestion would be try setting it accurately with a white noise test track and dual channel oscilloscope. Ignore what the dial says, just adjust until you get the same voltage on both channel.

    My expectation is that it wont be possible as that arms behaviour is wild.

    Try it with both carts, if you can set the adikt but not the dv then you know where the fault lies.

    A soft faced dead blow hammer will straighten that chassis enough.
     
    Last edited: Apr 25, 2020
    torstoi likes this.
  20. 2ManyBoxes

    2ManyBoxes pfm Member

    The cartridge looks fine to me when it hits the record. I think the videos are pretty clear.

    I'm struggling to think how you would find out if the cartridge suspension is knackered. I suppose that you could get hold of another XX-2 and try them out on the same test record. Not a cheap option obviously :) particularly as Dynavector have recently chosen to change their prices from bargain to WTF :eek:

    Was it definitely in it's original packaging when you got it?
     

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