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Tonearm recommendation

Hello all,
Recently procured a Feickert Blackbird w/ the Jelco 12 inch tonearm.
The table is really good, and its a keeper. The Jelco is also very good, but not as good as my Fidelity Research FR66s. So the Jelco will eventually hit Ebay, and the question remains do I keep the FR66s or sell that and buy something modern in the 5-6 K range. My only point of reference is my old JMW-10 on my Aries MK1, so I don't know how the FR66s would compare to a modern arm. So I'd like to rely on the collective knowledge and experience of this group for a recommendation.

Keep the FR66s, or go modern in the 5-6K range, say a Moerch DP8 or maybe an SME.

Any and all thoughts and opinions are of course much appreciated.

Cheers,      Crazy Bill
wrm0325
fleib
1,124 posts
 

Someone is not paying attention. Dynavector nulls were just posted and they are not Stevenson.  The inner null is close to it, but outer null is Loefgren B.  How does this change tangency and alignment error?

http://www.vinylengine.com/tonearm_database.php?make=Dynavector&mdl=&sort=2&eflo=&ef...=

Click on the nulls to find out.  Scroll down to the columns headed with the stock and standard alignments. Notice the odd relationships between various alignments with regard to eff length, offset, and overhang.

What remains constant?  Pivot to spindle = mounting distance. 

The equation is L = MD + OH. Where MD is mounting distance and OH is overhang. If L remains constant, then the values of MD and OH change for different alignments, but still total to equal L. 

Forget about Loefgren's papers, it's all right there. You're confusing yourself trying to reinvent the tonearm. If you start doing the math for different nulls, your arm will be released around the year 2127, or the 2nd of never.

What interests me is the DV total alignment error - looks pretty good. They say "Distortion figures are calculated from samples of tracking error in the modulated groove area." Samples?   Sounds like smoke and eyewash. Distortion analyzer?

fleib
1,124 posts
 
Distortion analyzer should say measured.  Probably smoke and eyewash.
dover
2,249 posts
 
The reason some people find those zero offset arms sound good, is reduction of torsional forces on the cantilever. Do linear arms solve these problems? If and only if, they can maintain tangency at all times and otherwise behave as a proper tonearm Re: mass, friction, etc.
Fleib,
Don't you mean the other way round. If an arm has zero offset vertical bearings then there will be torsional force on the cantilever when the arm moves up and down. If the tonearm has offset vertical bearings that match the cartridge offset, then there will be no torsional force on the cantilever when the arm goes up and down, however there will be additional torsional force on the bearings with an increase in bearing friction in the vertical bearings.
Your comments on the Dynavector make sense, the arm comes with a jig for the cartridge which if followed the cartridge ends up dead straight in the headshell with the vertical bearings aligned. If Baerwald A is used in the Dynavector then the cartridge is offset from the vertical bearings and torsional force is introduced into the cantilever. This is probably not a good thing in such a short arm.

Post removed 
fleib
1,124 posts
 

Dover, Interesting comment. The straight zero offset arms available today address lateral torsional forces.  The ViV Rigid Float requires little or no antiskate as a result of this. Skating force is increased by cart offset, that is lateral cantilever angular difference between pointing at the pivot and pointing at offset angle. There is still skating because the cantilever is tangent to the groove at only one null point on an underhung arm, but it's said to be insignificant.

The only arm I've heard of that addressed lateral and vertical torsion is RS Labs. That one had the pivot elevated so the zero lateral offset cantilever would also approximately be vertical zero offset.

The trade off with alignment error is significant, but reviewers say it's worth the trade. Ironically, they also say the shorter version sounds better. This is supposed to be because reduction of length also reduces arm resonances, or something like that. It's conjecture but makes sense. 

My skepticism with distortion figures and alignment error correlations isn't based on these arms. There is necessarily a phase difference between channels with lack of tangency, but it seems to me any other distortion would be cantilever and tip dependent.

Regards,

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