The blade reminds me very much of a spring. Are you sure the VTF is constant regardless of the warped record? As far as my mechanical imagination goes, your bearing point will always move slightly up and down. Nothing that you can normally hear. In addition, the blade brings with it a moment that does not exist with a thread.
Best regards
Arndt
Hi Arndt,
What I call it a Blade, despite its small thickness of 0.2mm, act like a kind of flat spring. In fact Martin called it Flex Bearing, but if I understand well the flex bearing have a kind of counter rotation, a spring back reaction. This blade do not have it for the H rotation. For the V motion hard to say as TA mass get involved.
However the main principle it is the same as the original Supatrac plus a bearing for the hoist that in theory avoid Azimut difference and in theory keep more steady the VTF as no twisting of the hoist, Bias more simple to be controlled.
The blade accompany the rotation of the hoist bearing in a more direct way than the 2 hoist could do, therefore I think the thrust box rotation with the blade is more timing/syhncro.
The top blade clamp avoid that the blade is leaning ( Thrust box ) in any direction ( right or left ), the clamp shaft is locked to the small 3x8x4mm ceramic bearing ensuring a good and steady rotation. Th shaft diameter, 3mm in brass it is strong enough I think for this purpose as the bearing dimension.
The Supatrac pivot ( bearing ) keeps the H line with the 2 screws that lock the blade in the lower thrust box. Here come the first difference as the blade have a certain surface of contact with the thrust box as the blade it is locked therefore some theory of the original Supatrac bearing is gone. Same happen at the top as blade is locked in the clamp.
The vertical line between the blade axis at the top and the thrust box surface has the same principle as the original therefore a very minimum leaning. This leaning in my case make kind of S shape of the blade and there happen its deflection and pressure of the thrust box against the H pivot.
To avoid possible moment or let s say short comings the precision of the whole unit needed it is more difficult to achieve for a DIYer like me without special machinery.
However the thrust box turn around the sharp tip of the pivot in every direction.
I tuned up the TA in a way that the blade have the very very minimum force necessary to keep the thrust box and pivot in contact. Also its rotation for the entire side of the record act like the Supatrac with the TA wand in balance in H position behave like it is in the NULL POINT.
Are there extra moments comparing to the 2 standard hoist? Most probably yes especially with my execution that I knew could not be realised enough accurate.
Does this affect the sound? May be yes, may be not, I could not hear today, the magic of the Supatrac bearing was all there in my rig, but as I said the sound in LP reproduction has sooo many variables that I like to avoid to talk or comment.
My impression of the 2 mods ( bearing plus blade ) and not blade alone was:
The overall benefit exceed the short comings, however as I said the bearing in my opinion and to my rough clone is positively good.
Blade, if you are bored and you like to do something to your TA, since implementing the hoist bearing, could be an inspiring experience that make worth the extra effort.
Best regards
Adelmo
