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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
 

Raul, My job is being a consultant to you? This is news to me, am I on the payroll? Maybe a flat fee for consultation, or maybe I misunderstand. I thought this thread is about high quality arms around $6K or less. It looks like all the DV arms have the same geometry and the 507 may look a little weird, but I don't care about that.

I thought I was your geometry teacher - remedial 101. I guess not because you're assigning the curriculum.  This is confusing, and to be honest, Griffithds would be a better consultant/teacher. He comes highly recommended and has experience in the aerospace industry. He's practically a rocket scientist. I'm quite sure he's forgotten more than I know about math, the problem is how much does he remember?  Remember his post admitting to brain flatulence? Not much to worry about on that score though, he can consult from home.

You know the bit about feeding the hungry - teach someone to farm and he can grow his own, or something like that?  That was my teaching plan.  Know any algebra? You're supposed to pass algebra before you take geometry. How can you solve an equation without algebra? I think you just push buttons without understanding and want someone to tell you which buttons to push?  Know what an equivalency is - 2 sides of an equation? L = MD + OH   L = 10" = 254mm.

254mm = pivot to spindle + overhang. L is your constant and you need 2 numbers that add to 254 for the other side of the equation. To find those numbers for any standard alignment go back to VE calculator and put in 254 for effective length. If that doesn't work find a 254mm arm in the database and click on the nulls. That will give the other numbers.

That's the best I can do. My specialty is solid geometry and my brain is farting like crazy. They told me I was filling in for Professor Timeltel. I thought he was an English Lit prof. I think I was conned. Did Timeltel retire? I don't know what's going on, but Griffithds is your man.

Regards,

Ag insider logo xs@2x
rauliruegas
13,101 posts
 
Dear lewm: Dynavector specs are really odd because don’t even the theoretical Stevenson calculations with the 241 effective length, 226 P2S and the 21.5° in offset angle they writed as tonearm specs.

Using IEC standard the nearest ( Stevenson. ) equations calculations gives:

L = 241.162 overhang: 15.162 and offset angle: 21.624° for the specification of P2S: 226.

Seems to me that even the manufacturer calculations are not accurate neither the protractor that comes with the tonearm.

Btw, when you used Baerwald in that tonearm: did you changed the P2S distance?, because it must be change it.

In the other side the difference between the Baerwald/Stevenson offset angle is lower than 1.5° but the other Baerwald parameters must be take in count in precise way.

Anyway, what do you think about the Löfgren papers/equations and the fixed parameters/foundation data those papers/equations states?

I’m asking you because, as always, fleib never gives a direct answer about.

Could you help? or maybe: Dover?  griffithds or: some one else?

I think that must be at least one other person with the precise and right answer even if is different answer from my opinion.

Answers are appreciated.


Regards and enjoy the music,
R.


fleib
1,124 posts
 

Dear Raul, You wound me deeply. I was the greatest tutor in all of the Americas, and look what I have become. I have failed you. Now I am just a hollow shell of a tutor, like an empty tortoise shell in the sand, I'm a dead tortoise tutor, not to say I tutor dead tortoises, but my tutoring, he is very sick. I thought I answered all your questions, but usted no entiende.  Si me lo permite.

Yes, the Loefgren calculations are correct. They are the basis of all the others. The spreadsheets, VE calculators are the same thing in different formats. Your answers should be the same. If you start out with L the spreadsheet or calculator will show you M distance, offset, error, etc. for each alignment.  I don't have your spreadsheet. I told you how to access the calculator. You don't need to log in.  Follow my instructions and it's all there. If you can't use the spreadsheet or calculator I suggest you build something else. How about a nice headshell holder display block? 

Regards,



Ag insider logo xs@2x
rauliruegas
13,101 posts
 
fleib: Finally! a more direct answer from you, good. I have no time now to give my point and I will give latter on.

Thank's.

R.
dover
2,249 posts
 
Fleib/Lewm

I calculated the effective length required to achieve a 21.5 degree offset with Lofgren A for the Dynavector arms. This would result in the cartridge being in line with the vertical bearings.

Using the formula
Effective Length = (r1+r2) / [ (sine(a)*[ 1 + ((r1+r2)squared / (r1*r2))] ]
where r1/r2 are the nulls & (a) is the offset angle.

Result is effective length of 254.97 and overhang of 16.158.
This is impossible with the Dynavector unless you extend the length of the arm or headshell.

This underpins that one really cannot judge an arm without at least trying the geometry that the original arm was designed for. Furthermore Rauls contention that he altered the mounting distance for Lofgren A to optimise the performance on his Dyanvector was probably wrong unless he modified the arm.  

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