Uni-Protractor Set tonearm alignment


Looks like Dertonarm has put his money where his mouth is and designed the ultimate universal alignment tractor.

Early days, It would be great to hear from someone who has used it and compared to Mint, Feikert etc.

Given its high price, it will need to justify its superiority against all others. It does look in another league compared to those other alignemt devices

http://www.audiogon.com/cgi-bin/cls.pl?anlgtnrm&1303145487&/Uni-Protractor-Set-tonearm-ali
downunder
" dynamic balanced mode has a few good advantages vs static balanced mode - regarding guiding a cartridge with compliance through the groove of a record which is by nature NOT flat."
Excellent!
But what if this feature is the most critical ?
And what if we accept that probably the bearing friction on tonearms with ball bearings is considerably more than knife-edges, cardanics & unipivots, and this advanced feature can not incorporated in them or in a air bearing tonearm...
Does this pointing us the way of designing better tonearms?
Can we include this feature in a more sophisticated bearing ?
Dear Geoch, be careful not to fall into a "trap" here: Löfgren B IEC is NOT a priori better for those records cut close to the inner label!
In fact Baerwald IEC does sport way lower distortions towards the inner groove compared with Löfgren B IEC.
Löfgren B is way better in the middle 3rd of the grooved area, but has it's highest distortion figures towards the cutting limit.
A very dangerous error if one thinks that Löfgren B is better for wide cut records - it certainly is not!
Löfgren B is all about lowering the average distortion figure - but it does so at the expense of the inner grooves.
If you want the lowest distortions possible in or towards the inner groove - which is wise BTW .... especially if you listen to symphonic music and have a large collection of records from the 1950ies and 1960ies - you should have a good look at Stevenson, as it puts the focus exactly on that: lowest distortions and zero error point at cutting limit.
This again is just a general guideline - not meant as a generalization.
Cheers,
D.
Dear Daniel, it is my fault not to be clear about this. My LPs are all from '70s and I don't have but a few classical symphonic music so, I prefer the Loefgren B IEC, all the time.
Dear Geoch, it is an important feature, but it is only one important feature among a good half dozen others.
Knife-edge bearings do have a good bundle of problems too.
Some of them are quite severe and do limit the performance of a knife-edge tonearm - that's why I personally abandoned the knife-edge bearing pretty early in the development of my design.
Low friction isn't everything (in fact - it is negligible in all better tonearm bearings today).
You should address this topic in a separate thread and I can assure you that you will get many posts and comments by some of the more active A'goners as well as by some tonearm designers.
Please do start that thread.
Cheers,
D.
Dear Daniel,
Interesting comments on arms with knife-edge bearings?
The SAEC arms with double knife-edge bearings enjoy quite an enviable reputation amongst the 'vintage' fraternity with Thuchan even ranking the 12" versions competitive with the FR series tonearms?

I wonder if you might expand on the weaknesses you find in this solution.......especially since I have a new addition to my arm collection arriving shortly.......namely an SAEC WE-308?
Cheers
Henry