So far I have built the Linn-compatible version only. I have a little more work to do to produce Rega and ARO mount versions.
Apologies for skipping the junction box question. The arm wires have D-sub 'clothes peg' connectors on both ends. Inside the arm pillar they push on to brass pins which continue down and are the male DIN connectors. The DIN plug pushes up into the arm pillar in the normal way. This means that you can easily remove the arm while leaving the column installed. A through wire clamp is also supplied so that it is easy to replace the arm wire with one stretch of wire to the preamp if you have an interest in such modifications. If I get a moment I will upload 3D graphics of these arrangements.
I found the time so here is a transparent 3D view which shows the internal electrical arrangements of the Linn-compatible arm pillar. Next to the pillar are the internal plugs and connectors which are locked in the arm pillar by two grub screws visible in the pillar. If you loosen these grub screws you can replace the plugs and rods with the clamping part shown on the right (supplied with arm). The clamp enables the attachment of a shielded phono cable whose signal wires go through to the cartridge.
Rega and Naim ARO mount versions are being developed. Since their columns are narrower it is likely that they will be through-cable only designs, but I intend to retain the ease of replacing the arm wire as I know that many users have strong preferences about that.
Rega and Naim ARO mount versions are being developed. Since their columns are narrower it is likely that they will be through-cable only designs, but I intend to retain the ease of replacing the arm wire as I know that many users have strong preferences about that.
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Adam of hifiaf.com has published the first vlog review of the SUPATRAC Blackbird:
SUPATRAC Blackbird Tonearm ? Review and Explanation - YouTube
SUPATRAC Blackbird Tonearm ? Review and Explanation - YouTube
Adam has also written up his experience of using the Blackbird for the last two weeks:
LP12MF: SUPATRAC Blackbird Tonearm Installation and Review – hi-fi AF
LP12MF: SUPATRAC Blackbird Tonearm Installation and Review – hi-fi AF
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Good show Caruthers! Taking it a step further you could raise the point contact (with string hang off point above it) up to where it is line with the cantilever. Like the A1 unipivot arm.
Then you don't have the cantilever compliance in the picture. ie stylus / cantilever / point contact are in a straight line. But it might sound worse with no compliance.
Then you don't have the cantilever compliance in the picture. ie stylus / cantilever / point contact are in a straight line. But it might sound worse with no compliance.
Yes, there are different cartridge heights to bear in mind. Most normal cartridges will put the pivot at or slightly below the record by a millimetre or two with a Blackbird. Most arms pivot ten or 15 mm above the record. I actually think slightly below the record is ideal since that delivers a slight increase in downforce when the going gets rough, whereas 15mm above record level will cause a dip in downforce just when you don't want it.
Another way of doing it with exactly the same resolution of forces would be to replace the string with a unipivot where the apex of the string is.
You could call it a duopivot.
You could call it a duopivot.
Sorry, that's rubbish, the string combines the forces. Makes me see why it is such a good idea. I really like it.
I nearly replied but was struggling to envisage what you had in mind. It's a mind-boggling problem, which is why it took me 30 years to have one good idea and I was led to it by people who are actually clever, like the great Messrs Firebaugh and Kuzma.
It has that elegant simplicity that nobody gives you credit for, because anyone could think of that! But they didn't. So well done caruthers.
Interesting if you get a patent. A suspended tonearm constrained by a magnet is the closest perhaps. The Well Tempered arm is dynamically constrained by viscosity I guess. And inertia. A single horizontal point contact is so nice. You can replace the string with other point contacts but then you have a one sided gimbal...
I once measured stylus 'drag' force on various records using an arm mounted on a Linear Motion Table and a stylus wt gauge. It's not much! Once you start biasing the point contact force with some string angle the point starts moving up and down on the pad with arm rotation. It probably does a bit even with vertical string arms as they twist. Maybe a low friction teflon pad would be good.
Interesting if you get a patent. A suspended tonearm constrained by a magnet is the closest perhaps. The Well Tempered arm is dynamically constrained by viscosity I guess. And inertia. A single horizontal point contact is so nice. You can replace the string with other point contacts but then you have a one sided gimbal...
I once measured stylus 'drag' force on various records using an arm mounted on a Linear Motion Table and a stylus wt gauge. It's not much! Once you start biasing the point contact force with some string angle the point starts moving up and down on the pad with arm rotation. It probably does a bit even with vertical string arms as they twist. Maybe a low friction teflon pad would be good.
Thank you. Yes, it was there waiting to be discovered.
I didn't quite understand your third paragraph. Do you have the patience to elaborate? I'm very interested in the effects of stylus drag on arms and platters...
I didn't quite understand your third paragraph. Do you have the patience to elaborate? I'm very interested in the effects of stylus drag on arms and platters...
Ive had a front seat to the final stages of the Blackbirds development over on another forum and its been awesome watching this new and unique arm reach fruition.
I'm also grateful for the interest, opinions and good advice I've received on several forums from people such as yourselves.
I posted results of measuring stylus 'drag' here on LH with photo. Reply 9 and 10.
https://www.lencoheaven.net/forum/index.php?topic=29330.0
If your string hangs vertically above the point contact you get about 0.6gms force on the point.
If you move the string hang off point forward to bias more force on the pivot point then the rotation plane becomes angled. The lower end of the string arms have to follow that plane. If the point is fixed as in a cup then the arm rolls slightly around its axis. But I don't think it matters.
https://www.lencoheaven.net/forum/index.php?topic=29330.0
If your string hangs vertically above the point contact you get about 0.6gms force on the point.
If you move the string hang off point forward to bias more force on the pivot point then the rotation plane becomes angled. The lower end of the string arms have to follow that plane. If the point is fixed as in a cup then the arm rolls slightly around its axis. But I don't think it matters.
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Nice work! Interested, when you get the LP12/ARO version completed.
Most of the bearings in a traditional turntable and tonearm are 90 degrees out from how they should be used... 🙂
How do you solve the antiskating in unipivot designs?
I think i saw the well tempered turntable a while ago, two years after i have built the water sliding linear tonearm , buti don't think i see any antiskating system working reliably in an unipivot system as it affects the azymuth at all times .Unlike the well temperate turntable design,it looks like you're using the air to damp the tonearm before it setteles which means it will oscillate a lot before settling unless the wires are rigid in horizontal plane which would kill all the unipivot tonearm advantages .Fixed bearings might not look cool from a resonance point of view or from , but it solves a lot of the problems and The well temperate turntable considered that viscuous silicon oil damping for a reason.The Most Ingenious Turntable from the 1980's - The Legendary Well Tempered Record Player (WTRP) - YouTube
I think i saw the well tempered turntable a while ago, two years after i have built the water sliding linear tonearm , buti don't think i see any antiskating system working reliably in an unipivot system as it affects the azymuth at all times .Unlike the well temperate turntable design,it looks like you're using the air to damp the tonearm before it setteles which means it will oscillate a lot before settling unless the wires are rigid in horizontal plane which would kill all the unipivot tonearm advantages .Fixed bearings might not look cool from a resonance point of view or from , but it solves a lot of the problems and The well temperate turntable considered that viscuous silicon oil damping for a reason.The Most Ingenious Turntable from the 1980's - The Legendary Well Tempered Record Player (WTRP) - YouTube
I agree with all of this. I displace the suspension point a small distance towards the stylus to maintain contact with the pivot in the absence of drag force. Both the pivot position and the suspension point are adjustable by a few millimetres on the Blackbird. This enables optimising spindle/pivot/stylus distances for particular decks and cartridges, within limits. It is the job of the installer to ensure that there is adequate overhang for reliable contact to be maintained at thre pivot, but not so much that bias becomes unmanageable in the way you have described.