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

sonddek said:
Don't hold your breath for the turntable. I still have a lot to do with tone-arms before I crack that nut. I know how I'm going to build it - I just can't see it becoming a product very soon.
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I look forward to it. I'm particularly interested to see how you manage the sideways main bearing...
 
Toaster said:
I look forward to it. I'm particularly interested to see how you manage the sideways main bearing...
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The only platter bearings which have ever made sense to me are those in the Well Tempered decks. I am very suspicious of round pegs in round holes. I pay for them, as we all must, just as I pay for QWERTY: in more ways than one.
 
Hi Sonddek, given the choice between a WT Amadeus Gta platform and a Technics platform which would you put your arm on?
 
MVV said:
Hi Sonddek, given the choice between a WT Amadeus Gta platform and a Technics platform which would you put your arm on?
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Aaarrrgh. Don't make me do this. I love them both. I suppose it's fun to have the wolf in sheep's wool effect of the old DJ deck, which can compete with the very best once you upgrade the arm. OTOH the WT decks are so clever and so simple. I bought a spare motor for mine. It cost £3. Firebaugh's minimalist approach means that you can always DIY maintain the deck, so it will last forever. I make new belts with fishing line.

Out of the box I think the WT decks are slightly better due to the arm, but once I've upgraded the arms I can't decide.

Also there's a question of VFM. Look at the new prices of SL-1210 Mk7, SL-100C and 1500C. Even the GR is a steal, but those cheaper decks will outlive you and never skip a beat. I think we're in a golden age for record players. Wish I could say the same for new pressings.
 
I knew it wasn't a nice question. But I've got both however would need to buy another technics deck if I went for your arm cos mine is an anniversary with the horrid gold arm (It's a keepero_O) Can you get them without an arm?
 
MVV said:
I knew it wasn't a nice question. But I've got both however would need to buy another technics deck if I went for your arm cos mine is an anniversary with the horrid gold arm (It's a keepero_O) Can you get them without an arm?
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Changing arms is so simple that you could change back to the stock arm and nobody would ever know. There are about twenty screws into the bottom of the deck, but is someone really going to examine them for wear marks? And they're specified by Technics, so there probably won't be any wear marks. I would swap in a Blackbird and then swap the stock arm back in if you ever decide to sell. One proviso: I'm judging this on my G, not your Mk7, so I'm assuming that there is not a higher level of difficulty. I understand the Mk7 is modelled on the older 1200s, so it should be easily doable. It was always designed for arm-swapping.

Another interesting option is to get a really cheap used Mk2 or Mk5 with a broken arm. Remove the power supply to a separate box, attach the Blackbird, and you have a monster of a deck for a very, very competitive price. I also recommend taking out all the screws in the base on the old decks because I think there's a possibility that the coupling to that heavy rubber base accounts for some of the 'deadness' of which these decks are sometimes accused. There is nothing dead about my Mk5 - it's scary real. It sits in the rubber base, but is less well coupled to it without screws, and the base sits on an inner tube. It was sounding lovely at Munich High End and George of Moonriver, who was skeptical about replacing their Brinkmann Bardo/10.5 with a bashed-up ancient Technics at the Munich show until he heard it, around the corner from decks by Oswalds Mill, Nagra, Techdas and Döhmann, loved the sound of it so much that he called it 'genius'. I have been invited to share an exhibition room with this group next year and they have ordered three arms, if that gives you an indication of their reaction.

It was a bit surreal sitting there with Ricardo Franassovici of Absolute Sounds asking Mark Döhmann what it was about this deck that he liked, and Döhmann replying "the timing and the dynamics". Surreal and very exciting.

BTW, I can supply Blackbirds in any paint colour which I can mix up from the Cerakote C range, so a colour-matched Blackbird on your Mk7 might make it more collectible, not less so...
 
sonddek said:
The only platter bearings which have ever made sense to me are those in the Well Tempered decks. I am very suspicious of round pegs in round holes. I pay for them, as we all must, just as I pay for QWERTY: in more ways than one.
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I suspect you'd probably favour a design something like the Opera Consonance Wax Engine- basically a WT Simplex 2 in a different chassis, with their arm. Perhaps you could talk to them about an armless OEM version? Looks like Jelco 9" geometry on the standard deck, but there seems to be a 12" version too.
 
Toaster said:
I suspect you'd probably favour a design something like the Opera Consonance Wax Engine- basically a WT Simplex 2 in a different chassis, with their arm. Perhaps you could talk to them about an armless OEM version? Looks like Jelco 9" geometry on the standard deck, but there seems to be a 12" version too.
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Wow - thanks for alerting me to this - I was completely unaware of this turntable. I love the design - simple, logical, minimal. I'm tempted to add yet another deck to my stable. I suspect I will like it more than my Amadeus since it contains all the components in the right places and without the unnecessary mass of the plinth.

I believe I met the proprietor of Opera Consonance at Munich, and I remembered that they build the Well Tempered decks, so I was impressed. I'm very interested to learn more about him and the company.
 
No problem! I thought you'd like it, although I also thought you'd probably already come across it, given the WT connection. I'd consider one myself, if it wasn't for all the other decks. Nice and simple, WT running gear, nothing expensive to go wrong, and I like the look. Just the thing to put a Blackbird on, except that neither of mine are the right length, and it might need a custom diameter pillar as well. Not an issue for you of course! Could even be a potential manufacturing partner down the line, or a licensing deal perhaps?
 
SUPATRAC continues to be unlucky with mentions by hifipig. In their Bristol report they simply say "SUPATRAC - the room was closed when we passed", and their Munich report says "Unfortunately no one was free to speak to me when I passed by the stand." What's strange is that I recall talking to hifipig reps on both occasions, and the Munich comment is actually accompanied by pictures they took of both myself and my beloved wife demonstrating the product to them. I'm not sure how we should go about achieving more favourable coverage.

Perhaps I need to find some funds for placing an advertisement.
 
Toaster said:
No problem! I thought you'd like it, although I also thought you'd probably already come across it, given the WT connection. I'd consider one myself, if it wasn't for all the other decks. Nice and simple, WT running gear, nothing expensive to go wrong, and I like the look. Just the thing to put a Blackbird on, except that neither of mine are the right length, and it might need a custom diameter pillar as well. Not an issue for you of course! Could even be a potential manufacturing partner down the line, or a licensing deal perhaps?
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I will certainly be looking into this.
 
sonddek said:
I have reached the conclusion that arm designs are flawed, even the 4point, and that no arm design takes seriously the problem of oscillating stylus drag in the time axis.
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How should a non-flawed arm deal with "the problem of oscillating stylus drag in the time axis"?
 
andyr said:
How should a non-flawed arm deal with "the problem of oscillating stylus drag in the time axis"?
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Orient the bearing to oppose it.

When you think about the 4Point, three of the four contact points are oriented so that stylus drag is dragging the point across the thrust surface, not straight into it. Arguably the lower point on the yaw axis will hold, but both points on the pitch axis are oriented to oppose gravity, not the oscillating drag. It's a brilliant design and without the 4Point design and the Well Tempered I probably wouldn't have thought up the SUPA bearing. I was certainly thinking about whatever flaws might be in those designs and others when the SUPA bearing occurred to me.

Cardanic bearings aren't much better. There are several contact points and their opposition to gravity is probably more consistent than their opposition to stylus drag.

My views on this are guesswork and just one amateur's effort to understand what happens in dynamic situations at contact surfaces down below the micro scale. I'm sure I'm wrong about most of it, but in making my own arm I had to start with some assumptions as I hadn't the resources to do properly funded scientific research. My solution was expedient: reduce the number of points of contact and orient them (it) to oppose the dynamic forces, not the static ones.

I hope that clarifies what I said in the quote. I think it's the crux of why SUPAs, even quite bodged DIY ones, perform so well.
 
sonddek said:
Orient the bearing to oppose it.
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Sure, that makes sense ... but I have NFI how this might be organised. :(

sonddek said:
When you think about the 4Point, three of the four contact points are oriented so that stylus drag is dragging the point across the thrust surface, not straight into it. Arguably the lower point on the yaw axis will hold, but both points on the pitch axis are oriented to oppose gravity, not the oscillating drag. It's a brilliant design and without the 4Point design and the Well Tempered I probably wouldn't have thought up the SUPA bearing. I was certainly thinking about whatever flaws might be in those designs and others when the SUPA bearing occurred to me.

Cardanic bearings aren't much better. There are several contact points and their opposition to gravity is probably more consistent than their opposition to stylus drag.
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So how does the bearing of the 80s 'Magnepan Unitrac' stand up, in your estimation?

This is a UP - 'xept the point sits inside a ball race (so the spike is supported against chattering, a short way up) ... rather than sitting in a cup.
 
andyr said:
So how does the bearing of the 80s 'Magnepan Unitrac' stand up, in your estimation?

This is a UP - 'xept the point sits inside a ball race (so the spike is supported against chattering, a short way up) ... rather than sitting in a cup.
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I don't know. I've heard of it, but if it sits in a ballrace it's not really a uni-pivot. A spike in the middle of a ballrace is probably not too bad for yaw, but where is the pitch axis? Sounds like it could have a lot of instantaneous friction against desired movements.
 
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