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?
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.
