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SME V centering problem

Discussion in 'audio' started by Cool_jeeves, Jan 10, 2021.

  1. Vinny

    Vinny pfm Member

    The opposite to having the cart' connected correctly?
    In which case, the cart' is a dud.

    You don't need to do anything else if this is the case, except fit another cart' and sort the dud.
     
  2. Cesare

    Cesare pfm Member

    I think the first step is to try with a different cartridge and to examine that one closely. If it's behaving weirdly, there is of course the chance it's knackering up your records, so be careful with it till you've decided where the problem lies. The easiest I imagine would be to swap the cartridge onto another deck and see if the problem follows the cartridge. This is where removable head-shells would be handy...

    Let's assume the diamond isn't aligned quite correctly, and is putting pressure on the groove in a weird way giving you this effect. As you play through the side the curvature of the groove changes, so I can imagine some sort of alignment which would cause problems at the beginning vs the end of the side, even if everything else checks out visually.

    If the problem were across the entire side, it would suggest anti-skate is turned up too high (I think that's right, the left is the inside of the groove?), so you could I guess try turning the skate down and see if this changes anything, but again, i'd be careful with an untrusted stylus on your record collection...
     
  3. Cool_jeeves

    Cool_jeeves pfm Member

    Sorry - i misread this to mean swapping tonearm leads. let me try swapping cart leads - but I am pretty sure I connected them as specified in the ART 9 manual in the first place. That and swapping back to another cart, DL103R, which was playing correctly. Will try both in the next few days.
     
  4. Vinny

    Vinny pfm Member

    You have done essentially the same, and proved that the cart' is dud.
     
  5. Cool_jeeves

    Cool_jeeves pfm Member

    No...i left the cart leads unchanged. Just changed the connections at the phono stage by swapping left and right. I expected the image to switch to the other wide and it did. In any case I am mentioning that the image moves slowly to center on its own. And that after that it is perfectly fine. How does that make the cartridge a dud?
     
  6. Vinny

    Vinny pfm Member

    4 connections/leads, 2 for L and 2 for R, exit the cart' and travel down the armtube and then connect to 2 leads that usually end in phono plugs. Those plugs connect to either an SUT, head amp' or phono stage.

    What have you swapped? What was the effect? Now think about how that effect was achieved. Plus, another cart' works fine.
    You have proved that the dud is sending a consistently dud signal.

    For some reason, at certain angles to the groove, the dud cart' is preferentially reading one side of the groove. The stylus/cantilever DO NOT remain at the same angle to the groove throughout play - that much is an approximation and hence the need for careful set-up. Insofar as you have good results with one cart', I am assuming that you have set up the dud cart' correctly too.
     
  7. Sue Pertwee-Tyr

    Sue Pertwee-Tyr Well, I can dream, can’t I?

    I’d guess that, given the OP explains that the cart is a refurb with a new cantilever, that the work done is in some way defective. Probably doesn’t take much misalignment to create an imbalance. So duff cart, send it back.
     
  8. Cool_jeeves

    Cool_jeeves pfm Member

    No way but to re-install the DL103R - verify all is well, then ART9 again (hopefully problem would have disappeared), then if it doesnt, send back. OK. Let me see... Painful with an SME V with its fixed headshell.
     
  9. Martin M

    Martin M Crueller than April

    Hi, if you have the phono stage selected and the volume turned up a little, if you touch the headshell with one hand and the amplifier with the other, do you get a bit of a humming noise through the speakers?
     
  10. Craig B

    Craig B Re:trophile

    Suggest you test play a record with anti-skating bias set to zero and then repeat play with it set to maximum. This should reveal whether or not stylus azimuth is ever so slightly misaligned and/or cantilever suspension integrity has been compromised during rebuild, with the combination of 'normal' AS force vs. decreasing groove radius (and therefore decreasing inside force) torsionally correcting the stylus azimuth as it moves inward.

    My supposition here is that one of these two play scenarios will result in poor image centering across the whole of the record, vs. the other possibly being an improvement from the off (or sooner than previously). I won't mention which of the two I suspect, as I'd rather not affect expectation bias. Best to ignore any reduction in Lch or Rch tracking ability, and simply listen for L vs. R level difference/image balance.

    Supposition based upon skating force as it relates to groove radius:
    [​IMG]
     
    Last edited: Jan 12, 2021
  11. Craig B

    Craig B Re:trophile

    @Cool_jeeves,

    I've been thinking about your dilemma and have been wondering whether there have been any developments.

    Craig
     
  12. Cool_jeeves

    Cool_jeeves pfm Member

    Hi Craig, i will be able to do this on the weekend only...there is also the Brisbane Test Match...On the sound problem, i will 1) play with min and then max antiskate 2) note each time when image centering starts to happen correctly 3) take apart the whole thing and get back to the DL103R and test for centering 4) repeat the whole thing with the modded ART9. And note down observations each time.
     
  13. Craig B

    Craig B Re:trophile

    Sounds like you've got your priorities well in order there, @Cool_jeeves! :)

    Not to criticize your intended methodology, however, I think that 4) would be redundant. Suggest the following:

    Should 1) return obvious different outcomes, subsequently noted in 2), followed by 3) confirming the problem to be the ART9 as being at fault, then 4) might be better as "consult with rebuilder as to why stylus (not cartridge) azimuth consistently changes across a record side".​

    What might really help here, is if you can get some close-up front-on photos of the stylus in the groove (relative to both record surface and cartridge body) taken under normal play during the first 10mins, and then again when the image centres, as well as during each of the max vs. min AS tests. These should be of benefit wrt assistance from here, as well as wrt any case subsequently presented to the rebuilder.

    From what you have described so far, I am of the opinion that a cantilever suspension tie wire adjustment may be the cure. It need by done by someone who is familiar with top AT MCs, as there is an art (no pun intended) to tuning these things. IOWs, it could end up perfectly and stably aligned but sound crap.

    audio-technica AT-ART9 MC (note the presence of two suspension adjust screws, the larger as anchor, the smaller as tuning dial):
    [​IMG]
     
  14. Jowcol

    Jowcol pfm Member

    Interesting how so many are missing the point that the fault goes away after playing half a side.

    If the cartridge has been rebuilt, then it is old. If it has had a new cantilever/stylus installed, then I assume it hasn't been completely rebuilt. That means the suspension is old. And I expect that after playing half a record side the suspension has been softened up......or something to that effect.
    Suspension rubber deteriorates. I think that is what your problem is.
     
  15. Craig B

    Craig B Re:trophile

    The OP reported the sound to be "perfect except that for the first half of each side of an LP, the sound is louder on the left channel than the right, and hence the image is formed to one side".

    IME, the first thing one notices with deterioration of rubber dampers is poor tracking ability and poor mid to high-frequency range performance. I've a few vintage 70s top end MMs here that sound absolutely horrid, despite their tips appearing perfectly fine under a microscope. I keep them in a cigar box labelled 'JICO?'
     
    Last edited: Jan 14, 2021
  16. Jowcol

    Jowcol pfm Member

    Yes, I read it wrong. First half of each side, I read it as first half side. Scrap my suggestion
     
  17. slawekt

    slawekt pfm Member

    Just a thought , have you checked if anti skate mechanism on your V works properly , it's based on tension spring and filament and it might not work as intended . Reset VTF to "0" and with no anti-skate applied tonearm should float freely in the air , slowly try to increase anti skate - tonearm should start drifting towards outside of the record/platter , also check position of the headshell while tonearm is positioned in the rest , corner should be approx 205mm from the spindle but check with manual ,
     
  18. Craig B

    Craig B Re:trophile

    Hello @slawekt,

    Following on from our discussion of dynamic forces at the phono cartridge from the other thread last week, I remembered having a copy of a document here that neatly summarizes various bits of articles going back as far as Electronics, from 1945. Anyway, I managed to find a link to an English version of this same tome on-line, although it seems to have been edited, going so far as the authors name being removed. Credit should go to Klaus Rampelmann, Den Haag (Niederlande), Mai 2015 (original article link).

    The English edited version document is also entitled 'Skating Force and Antiskating' (link). The 'Annex' portion of this tome does not exist in the original Rampelmann summary.

    The part that triggered my memory of this after last weeks posting was Fig. 11 – vector diagram of forces at the headshell (from [11]) in plan view. Note that skating force will only be at a perfect right angle to the longitudinal friction force Ff at the two tangent points.

    [​IMG]

    The aspect of this that I believe to be most relevant to the subject of this thread, has to do with looking at the forces applied from an elevation view perspective. The corresponding text of the article helps here, however, it is easy to see how rotational torque is applied to the stylus/cantilever (ignore 'vector.', a document formatting error). The square formed by solid line vector R* and the solid line portion of vector L* (as they relate to vertical tracking force vector Fv) would be for tangental tracking tonearms. The dotted line extension of vector L* indicates the extension of force due to tonearm offset which results in the net tracking force vector L (equal to Fv + Fs; Force vertical + Force skating).

    [​IMG]

    WRT @Cool_jeeves' issue here, I am convinced that the anti-skate mechanism is revealing compromised rotational torsion resistance in the re-cantilevered retip, vis-à-vis azimuth misalignment being the only geometric foil to accurate channel balance. I suspect that with AS set to zero the symptom may reduce, disappear, or even reverse channels over the first minutes of play where skating force is highest; see graph, post #30).

    [11] Alexandrovich, “New approach to tone arm design”, Audio Engineering Society preprint 149 (1960)
     
    slawekt and hermit like this.
  19. slawekt

    slawekt pfm Member

    @Craig
    interesting copy of the article :) , for the purpose of our last discussion we have simplified things a little as we analysed the null points only and we discarded force "L" on assumption of "perfect" anti skate, but I will have a read later on , thanks for the links .

    Speaking of the case on hand ,I think you're on to something with azimuth error also electrical channel imbalance could contribute to another 1dB difference at least .

    I would definitely check if anti-skate spring/filament assembly works at all as it would create similar effect if combined with mentioned above azimuth and imbalance errors , as stylus approaches middle of the record skating force decreases it's value - shifting balance to the right with negative peak in the middle of the record .
    Most likely problem was there before but sort of masked by less advanced stylus shape (haven't OP used Denon dl103 with an elliptical stylus?) not greatly affected by azimuth error .
     
  20. slawekt

    slawekt pfm Member

    Thinking about ... , more likely anti skating force is set way too high and as it's spring loaded filament it decreases as tonearm approaches spindle and at the same time skating force decreases approaching middle of the record , both shifting balance towards right channel and centering image shifted left by incorrect azimuth , as per Craig's advice try to set anti skate to "0" and see what happens.
     

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