Supatrac almost without counterweight?

[Adelmo]

Thank you Anthony, that is most helpful.  Look perfect for the job, though complete overkill    I hope they don't cost as much as C-Flex bearings !  I suspect they are only constant force if they rotate and then you have another bearing in the mix.  They are basically an extendable leaf spring.

Hi Adelmo, I understand now, thanks for the sketch and I enjoyed catching up on your build thread.   This is the magnetic rail tangential tracker you are making, hats off!  and to Frank of course.  I remember having a go at guessing how it worked when he gave some clues here early on.  Nice to see it in practice.

Is the hand shaking a result of the injury? I send you my best wishes and hope it improves soon.  

martin

Hi Martin,

Injury have recovered quite well, thanks.

Keep us posted for your new TA with spring CW project.

Best Rgds

Adelmo

[flood2]

Thank you Anthony, that is most helpful.  Look perfect for the job, though complete overkill    I hope they don't cost as much as C-Flex bearings !  I suspect they are only constant force if they rotate and then you have another bearing in the mix.  They are basically an extendable leaf spring.

Perhaps this is more suited to what Arndt was considering originally: https://springcompany.com/products/spring-reels/
"Spring reels provide lift assistance to any assembly that must be raised, reducing the “felt” weight. Field adjustments to pre-load and maximum travel can allow the reel to precisely counterbalance loads from less than one pound to over 50 pounds."

[wenig watt]

"What is more baffling is that you seem to be of the opinion that the Supatrac is somehow deficient in terms of tracking ability and arrogantly believe that you can improve on the Supatrac with a spring despite the designer of said arm already expressing his view on springs; if you already understand the physics, the various types of spring and how springs work then you wouldn't be asking for guidance, would you? "

Sorry Anthony,
I am not arrogant but curious and enjoy experimenting. I happen to know and appreciate Richard and his work. I happen to have almost every stereo Decca cartridge and tonearm there is. I happen to be not as stupid as you assume in your world view.
I asked about the properties of springs and you recommended a record ironing machine, or silicone damping or anything else you thought appropriate.
You can do that, arrogantly, because you think you know what I should know and what is right. That's OK for me. People who know something can pose with it. But I don't have to be ridiculed by you and the Viennese. If you were as great as you think you are, you'd be friendlier and more confident in dealing with the idiots you think I am.
Your condescension takes away your greatness.
Humour would be an alternative, but even that is just condescending. What a pity.
I value and honour knowledge that is shared. Richard's brilliant idea shared with all who care is a great gift to the community. Without condescension but friendly. Quite simply.



Best regards

Arndt

[behind the rock]

Regarding springs, I believe that a mod for the RB300 is to nullify the spring tracking application system in favour of using the counterweight as the spring allegedly colours the sound. I was thinking that a strip of POM C could possibly act as a spring, it would take a deal of faffing about to have the correct "springiness" but it would be less resonant and very light. Is there a figure for an actual spring set-up's mass and its centre of action to evaluate the inertia? If anyone remembers the Domus turntable it used metal strips, if I remember correctly instead of springs, to support a quite substantial sprung assembly.

Andy

[awkwardbydesign]

I expect that most of us also have fun reading about your experiments, I certainly do.  Please carry on.

[flood2]

I will have fun.

Kind regards

Arndt

Rather than reinventing the wheel, why not copy the Ortofon RMG-212 concept which is uses a spring for balance and tracking force but enables you to tune a suitable mass for a counterweight which will damp the action of the spring which is what you need.

[wenig watt]

Hi Anthony,
something like this happens automatically. Hence ‘almost without’. But the real problem is the force effect on the horizontal movement of the arm. So far I haven't had any anti-skating on my Supatrac clones. That could change now. But the exact adjustment has not yet been solved. Let me understand the results of my tinkering.
The reason for the positive behaviour of the Gray is most probably the non-linear behaviour of the springs.
Silicone damping is out of the question for me for sound reasons. It has a fatal effect on the dynamics. Then you don't need a Decca as a pickup.
The Supatrac bearing and a tonearm made of material with self-damping sound quite good. Mr Lederman has very nicely described the problems of vibration entering the cartridge and tonearm. The cactus needle is an impressive contribution to the subject. It sounds so much more natural than f.e. sapphire or ruby.
But this is probably an alternative reality for you.


Kind regards

Arndt

[be.audiophil]

Is this still the case?

I use the three-point attachment to realise a kind of anti-skating. Due to the type of arm suspension and the large total weight, a minimal inclination in the arm base is sufficient.

[flood2]

Hi Anthony,
something like this happens automatically. Hence ‘almost without’. But the real problem is the force effect on the horizontal movement of the arm. So far I haven't had any anti-skating on my Supatrac clones. That could change now. But the exact adjustment has not yet been solved. Let me understand the results of my tinkering.
The reason for the positive behaviour of the Gray is most probably the non-linear behaviour of the springs.
Silicone damping is out of the question for me for sound reasons. It has a fatal effect on the dynamics. Then you don't need a Decca as a pickup.
The Supatrac bearing and a tonearm made of material with self-damping sound quite good. Mr Lederman has very nicely described the problems of vibration entering the cartridge and tonearm. The cactus needle is an impressive contribution to the subject. It sounds so much more natural than f.e. sapphire or ruby.
But this is probably an alternative reality for you.


Kind regards

Arndt

The Ortofon spring/counterweight concept obviously works more reliably with a gimbal bearing since the spring function is isolated effectively to only operate in the vertical plane. However, the point of the Supa hoists is to achieve the same function which solves one of the obvious problems with a conventional unipivot which is the susceptibility to lateral instability which affects azimuth consistency which is on top of the fundamental azimuth sensitivity to arm height so you shouldn't have that problem with the RMG spring implementation.
I never suggested silicone damping specifically, but you need to reduce the Q at resonance somehow. Damping can be applied to the system via many means and the counterweight mass and spring reduce the Q of the cantilever resonance related to the effective mass of the arm. Carefully implemented silicone damping doesn't necessarily negatively impact the sound - what you describe is due to an over damped response caused by excessive viscosity of the fluid or surface area of the paddle. Rather than aiming for critical damping, it is better to just have just enough to reduce the Q at resonance enough to stabilise the system. I found this approach very effective to stabilise my high compliance Stanton/Pickering cartridges (CS100, 881IIS) which had a LF resonance around 6 to 7Hz in my arm.You are absolutely right that excessive damping results in a dull sound that lacks dynamics, but silicone damping itself isn't the main cause. I used a silicone rated at 60000cst and filled the bath just enough for my 3D printed paddle (which is very thin to minimise lateral resistance) to just break the surface of the silicone. 

As for cantilever materials, cactus needles certainly are amongst the stiffest of materials found in nature, but the modulus of elasticity still falls far short of corundum, diamond and boron particularly at the preferred length of around 6mm. I personally prefer these conventional stiffer options to shift the bending modes far above the audible range; a cactus spine would have to be much shorter to be equivalent. However, we all have different priorities and preferences in what we want to hear so I don't judge anyone else's taste in that regard.

As long as you have the means to digitally record the output from your cartridge, you can use free software like Audacity to analyse the effect of your changes using the silent groove on any record - you will be able to calculate the damping ratio and Q of the LF resonance even without a test disc.
I highly recommend this approach to help you with your experiment if you want to really learn from this project.

[eksiil]

it seems obvious to me that "science" did not predict the Supatrac arm (the starting point of this thread). the Blackbird was born out of practical insight and hands-on work & its inventor himself remains admirably open-minded & undogmatic as to why it does what it does so well. the OP fits squarely within that ethos.

"The owl of Minerva takes flight only at dusk"... in instances like these, theory can't but be an also-ran. what works will be established by those who experiment. (the fact that many experiments fail is an entirely different matter).

[Tomcat1969]

I think you are missing the point Rolf. I think this has blown up because you and others have been, at the least, ill mannered and condescending. You may have the scientific and technical knowledge to lend weight to your contributions but you may find that your pompous attitude will put people off.

[ian]

Because this topic is becoming polluted by unpleasant arguments I'm locking it to give the admins time to discuss what we should do.. 

[ian]

OK, I've been through this topic and removed some of the more offensive posts.  I've also removed some of the responses to them as these posts would look out of context.  Thank you to those members who contacted the admin team supporting Arndt and in a couple of cases apologising for their behaviour. 

Back to the fun and constructive comments.   

[Chrisg139]

Hi Everyone

Why don't we all just wait and then see what the results are- and then comment?

Cheers
Chris