Advertisement



  1. Things you need to know about the new ‘Conversations’ PM system:

    a) DO NOT REPLY TO THE NOTIFICATION EMAIL! I get them, not the intended recipient. I get a lot of them and I do not want them! It is just a notification, log into the site and reply from there.

    b) To delete old conversations use the ‘Leave conversation’ option. This is just delete by another name.
    Dismiss Notice

Sideways Uni-Pivot Arm, SUPATRAC Blackbird, formerly "Ekos Killer (Price?)"

Discussion in 'audio' started by sonddek, Sep 20, 2020.

  1. sonddek

    sonddek Trade: SUPATRAC

    Since a picture is worth a thousand words, I hope these clarify my rambling verbal minestrone above on the subject of the Blackbird's Linn-SME combined collar/base. In the first picture, for illustration only you can see bolts in both the Linn mount and SME mount holes. In the second you can see more easily the two distinct methods of bolting or clamping the base to an armboard or plinth. Note also the proud rings on the underside of the base where it contacts an armboard.

    [​IMG]

    [​IMG]
     
    Mr Pig likes this.
  2. Colonel_Mad

    Colonel_Mad pfm Member

  3. sonddek

    sonddek Trade: SUPATRAC

    Wrong thread?
     
  4. sq225917

    sq225917 Bit of this, bit of that

    You could say this tonearm has taken off...
     
    Marra likes this.
  5. laughingboy

    laughingboy pfm Member

    Your arm is absolutely fascinating. So much so, that I've been wondering if it can be simplified still further, for aesthetic and cost-cutting reasons. So, here's my idea. Would it be possible to get rid of the inelegant hoist spools altogether? Couldn't the two hoists be just one piece of string, something like a necktie whose two ends are held apart but converge at the neck to a single point?

    Trying to explain without a diagram will be tricky, but imagine that your tonearm's post were shaped something like a claw hammer. The hammer would be at the top, facing towards the cartridge, and the claw would face the thrust box. If you fixed the hoist string to the bottom right and left corners of the thrust box, you would be left with a loose loop of string between them. You would then lift the loop over the head of the hammer. The string would then be drawn upwards over the sides of the post and then draw down into the 'v' of the claw. From this point onwards, the two ends of the hoist diverge.

    In fact, if you slightly lengthened your hoist pipe design it could, at the front end, be the 'hammer/hook' and at the rear end, rather than a hole, be the claw or 'v'. In other words, unless I am completely wrong, it might be relatively simple to play around with the idea if this isn't an arrangement you have already tried.

    The three imponderables as I sit here and type are the following:

    1/How would this interact with your bias mechanism? I'd presume no change, but may be wrong.
    2/Would changing the tonearm's 'lean/azimuth' be as easy as using tweezers to slide the hoist string back and forth?
    3/ Would having just one string be practical when it comes to installation? There is not a lot of room around the pivot area, and it might be too difficult to hook the hoist loop over the post, once the tonearm wires are in place.

    Does that make sense?
     
  6. sonddek

    sonddek Trade: SUPATRAC

    Yes, it all makes sense, and I have examined these ideas many times. In particular, my first prototype wasn't far off what you describe, although I recognised the convenience of individual hoist adjustment even then. There are some difficulties with your suggestions as follows:
    - elasticity - you want the hoists as short and rigidly grounded as possible to avoid resonance, so hooking additional line under the hammer has a drawback
    - easy pivot height adjustment is necessary since the bearing is optimal when the pivot is precisely in line with the hoist fixtures on the arm
    - clearance - the extension of the hoist pipe eye and pivot point create clearance for the hoist trapeze to yaw around the support post without touching it
    - incision - the 'claw' needs to bring the hoists together at a point but not cut or wear them there
    - underhang adjustability by extending the hoist pipe enables optimising the bearing, whereas the 'claw' does not
    - snagging - the 'claw' will allow the hoists to ride over and disengage the bearing altogether leading to novice snafus
    - a mechanism which extended or withdrew both hoists would probably need to move, making the hoist grounding less rigid, and introducing needless complexity in mechanism and manufacture

    It is arguable that one adjuster for azimuth and another for pivot alignment would make more sense, but it's not simple to do this without putting one of the adjusters on the arm rather than the pillar, which would not allow you to adjust while listening.

    There are many implementations of this bearing which work, as the Lenco-Heaven discussion and DIY-fest proves, but the Blackbird incorporates a year of experimentation and makes a fair fist of being a practical tonearm with understandable adjustments and revolutionary performance. I'm very open to suggestions but will probably have to sift them and only introduce changes which offer a real improvement.
     
    Mr Pig likes this.
  7. laughingboy

    laughingboy pfm Member

    Thanks for the reply. It's such a fascinating design.

    I wish you every success with it.
     
  8. sonddek

    sonddek Trade: SUPATRAC

    Thank you!
     
  9. sonddek

    sonddek Trade: SUPATRAC

    A twelve inch Blackbird landed in Yorkshire yesterday. My hand is improving and I'm nearly back up to full steam.

    I've ordered 50 Linn-SME pillars and bases – it will be interesting to see how they compare to my handmade ones.

    I've also turned the first Rega/ARO/Jelco/VPI pillar which looks good. When it's finished I will post pictures.

    But 99% of my time is devoted to completing the arms of the customers who have ordered and paid. Only a handful of arms still to send now.
     
    Garrard 401, Mr Pig and Darren L like this.
  10. sq225917

    sq225917 Bit of this, bit of that

    This is new for pfm, people paid someone money and they made things and delivered them. You might want to post this the mdac thread... ;)
     
    Garrard 401, paulski, joe9407 and 3 others like this.
  11. sonddek

    sonddek Trade: SUPATRAC

    Another Blackbird has landed at the Berlin Audio Meeting. I was invited but sadly could not get there for this weekend.
     
    Alun Rains likes this.
  12. sonddek

    sonddek Trade: SUPATRAC

    There's a picture in this LH post of fourteen experienced and careful listeners assessing a tiny little Blackbird on a Technics SP10 which was only mounted on the deck within the preceding 24 hours. I believe one of the listeners is Frank Schröder himself. I really wish I could have been there for the fun and company, but I'm sure the owner did a great job of setting up the arm. Talk about a baptism of fire...

    https://www.lencoheaven.net/forum/index.php?topic=38374.msg475553#msg475553
     
    Last edited: Oct 13, 2021
  13. sq225917

    sq225917 Bit of this, bit of that

    Brilliant, if ever there's a man who's pondered bearings, it's Frank.
     
  14. yuckyamson

    yuckyamson pfm Member

    Richard. Huge boon if you can get his thoughts on it (Schroder).
     
  15. sq225917

    sq225917 Bit of this, bit of that

    Had to dig around to find it, but saw it eventually, looking good.
     
  16. yuckyamson

    yuckyamson pfm Member

    Since I can't rightly say I want to become a LH member and signup for the one post, can someone put a pic of it here?
     
  17. paulski

    paulski pfm Member

    You did better than me, gave up after 10 minutes.
     
  18. sonddek

    sonddek Trade: SUPATRAC

    I don't know the etiquette between audio enthusiast sites. Why not just sign up? It's free and they are very friendly. There's an epic 41 page Blackbird thread which documents several DIY versions of a SUPA bearing, invariably reporting unprecedented results.
     
    tiggers likes this.
  19. Bob McC

    Bob McC Living the life of Riley

    Have to be a member to see them
     
  20. sonddek

    sonddek Trade: SUPATRAC

    Yes, sorry - I forgot. Signing up is free though. I will leave the link there for those who are members or who want to sign up.
     

Share This Page





Advertisement


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice