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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
dertonarm
1,042 posts
 
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.
geoch's avatar
geoch
354 posts
 
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.
dertonarm
1,042 posts
 
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.
halcro's avatar
halcro
2,664 posts
 
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
thuchan
1,009 posts
 
Dear Raul,
understand very well. maybe we all have spent a little too much in too many different solutions regarding finding the exact geometry for our tonearms. I became happy with the Dennessen but did also see the limits for other installations when getting to know that some data inputs from some manufacturers for their own arms were not the right ones for special cartridges we are using. Therefore the situation for someone who deals with more than one tonearm/cart was calling for a universal approach. I have big hopes that the Uni-Pro is a good answer for those multi-users but I also wait with an assessment until I have made my own experiences with the sets ordered.
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