The necessity for absolute tt speed control

[morricab]

Speed is held with constant monitoring and continuous adjustment by the management software and a microprocessor not free spinning like an ac synchronous motor.which requires none of that.

david

So, are you saying that the AC synchronous motor is still the best motor technology for a turntable, belted or otherwise? What about brushless DC, which actually an AC motor that is sinusoially commutated...usually with 3 phases? What about cogging and torque ripple that is inherent in these motors, or do you think the mass and the belt smooth this out better than other tech? These actually don't run that accurate nor are they super smooth.

What about Brinkmann's coreless, Brushless motor (the Sinus) that will have no cogging and little to no torque ripple? They have figured out an analog speed control (actually I think a phase locked loop with quartz osillator is still analog...it's at least not the latest trend of PWM controllers that you can easily find off the shelf) and it seems to elevate their own high mass TTs. Have you tried something like this instead of your default Papst motor?

Is your main concern about "hunting" that old DD designs suffered from? What about later designs that employed sophisticated schemes that minmized over and undershoot?

 

[ddk]

So, are you saying that the AC synchronous motor is still the best motor technology for a turntable, belted or otherwise? What about brushless DC, which actually an AC motor that is sinusoially commutated...usually with 3 phases? What about cogging and torque ripple that is inherent in these motors, or do you think the mass and the belt smooth this out better than other tech? These actually don't run that accurate nor are they super smooth.

What about Brinkmann's coreless, Brushless motor (the Sinus) that will have no cogging and little to no torque ripple? They have figured out an analog speed control (actually I think a phase locked loop with quartz osillator is still analog...it's at least not the latest trend of PWM controllers that you can easily find off the shelf) and it seems to elevate their own high mass TTs. Have you tried something like this instead of your default Papst motor?

Is your main concern about "hunting" that old DD designs suffered from? What about later designs that employed sophisticated schemes that minmized over and undershoot?

What I'm saying is exactly what I wrote, the difference between how speed is maintained between two types of motors. The rest is your addition not mine!

Yes, I have tried other motors and so did Nishikawa San for AF0 but we both picked this particular Papst motor. I believe Win's using the same or a similar Papst from this motor family for his Saskia too, also having tried many other alternatives.

Never looked at Brinkman's solution, it wasn't necessary. I have lots of concerns about motors, longevity is a major one. One of these Papst motors been running 24/7 at 600 rpm for close to 6 years and at 1280 rpm since November. Torque curve and how well they maintain speed has a direct effect on the sound. Often things look great on paper or in theory but don't deliver in practice, a lot of the sound of the EMT 927 is attributed to the quality of it's to it's motor. I also like simplicity !

david

 

[YNWaN]

I’ve experimented quite a bit, over the years, with different motor options. All of the are, IMO, a delicate balance of compromises that they all share. In addition, there is an interaction between bearing drag and platter mass (effective or actual). For me, the best result I have achieved is a low voltage AC motor driving the platter via a relatively low compliance belt and a high drag bearing. This helps to mitigate the negative aspects of the motor whilst maintains the positive attributes whilst resisting (no pun intended) the temptation to over complicate the solution.

 

[microstrip]

It is curious that people focus mostly on the motor technique and forget about the belt. Friction and elasticity of the belt are extremely important, and could easily be quantified, but unfortunately they are systematically ignored. The same for the motor pulley characteristics.

Fortunately the TechDas AF1P manual includes a complete technical procedure to find the best best tension - one less tricky aspect to consider in set up!

 

[YNWaN]

Oh yes, I completely agree. I should have included pulley diameter and also suspension compliance but I was aiming for brevity. The whole is a system and ignorance of one can undo the whole. People (even manufacturers - or their marketing departments) concentrate on the obvious which is the overall drive system but ignore, because they don’t understand, the complex interaction of the supporting elements which are, as a whole, even more important.

 

[YNWaN]

The problem with the opinions expressed on forums (in general, not specifically this one) is that they are inherently based on people’s experience with owning whole products. By that I mean they are unable to separate the motor from the rest of the turntable, or if they are, it has other elements attached to it as part of the package. This isn’t a criticism, it is the nature of buying solutions from manufacturers. What I think we all know is that ‘everything matters’, at least to some extent . So I am saying we need to consider every element and how it interacts with every other element. What is unusual in turntable is that whilst they are quite simple mechanisms in terms of the elements used, those elements interact in a very complex manner and are often asked to perform disparate roles simultaneously (rather than discreetly). So, for example, the precise distance the motor is from the platter makes a significant difference, the way the pulley is attached to the motor shaft. In a DD the way the bearing is integrated, the way the motor is shielded, the way the logic of the CFL is applied etc. Differ t compromises, but related ones, for each system - different balances of importance/relevance and how easy they are to address.

 

[Lagonda]

The problem with the opinions expressed on forums (in general, not specifically this one) is that they are inherently based on people’s experience with owning whole products. By that I mean they are unable to separate the motor from the rest of the turntable, or if they are, it has other elements attached to it as part of the package. This isn’t a criticism, it is the nature of buying solutions from manufacturers. What I think we all know is that ‘everything matters’, at least to some extent . So I am saying we need to consider every element and how it interacts with every other element. What is unusual in turntable is that whilst they are quite simple mechanisms in terms of the elements used, those elements interact in a very complex manner and are often asked to perform disparate roles simultaneously (rather than discreetly). So, for example, the precise distance the motor is from the platter makes a significant difference, the way the pulley is attached to the motor shaft. In a DD the way the bearing is integrated, the way the motor is shielded, the way the logic of the CFL is applied etc. Differ t compromises, but related ones, for each system - different balances of importance/relevance and how easy they are to address.

Yes everything matters. Have you experimented with flywheels ?

 

[YNWaN]

No, not as such. I did theorise the idea many years ago but subsequent (unexpected - when I was looking into stylus drag) findings caused the balance of importance to change and so further investigation was abandoned. However, having looked at subsequent implementations I would say that many apply insufficient mass and difference in gearing to make the concept truly effective.

 

[Lagonda]

No, not as such. I did theorise the idea many years ago but subsequent findings caused the balance of importance to change and so further investigation was abandoned. However, having looked at subsequent implementations I would say that many apply insufficient mass and difference in gearing to make the concept truly effective.

A heavy flywheel attached to the motor, or as part of the motor makes a very audible difference. The flywheel acts not only as a torque enhancer but also as a micro cogging buffer, if you study some of the solutions MIcro Seiki, and Peter Forsell came up with you can improve most belt drive TT's, they where thinking out of the box, and had good ears.

 

[YNWaN]

A heavy flywheel attached to the motor, or as part of the motor makes a very audible difference. The flywheel acts not only as a torque enhancer but also as a micro cogging buffer, if you study some of the solutions MIcro Seiki, and Peter Forsell came up with you can improve most belt drive TT's, they where thinking out of the box, and had good ears.

but its not enough to say the flywheel is ‘heavy’, it has to be considered relative to the gearing and the mass of the platter. Ultimately the question is what is driving what and which is the master - the motor or the platter, or flywheel. In many cases the interaction is not at all clear and at some times one is in control and at other times it is the reverse.

 

[Lagonda]

but its not enough to say the flywheel is ‘heavy’, it has to be considered relative to the gearing and the mass of the platter. Ultimately the question is what is driving what and which is the master - the motor or the platter, or flywheel. In many cases the interaction is not at all clear and at some times one is in control and at other times it is the reverse.

Relatively light platters like Brinkmann's use about half a kilo flywheel connected to the drive shaft the Forsell flywheel looks heavier than that . I use a 100 lbs platter and have had good result with increasing flywheel mass to about 4 kilo, my flywheel is a integral part of the motor rotor, from a special edition R2R. The difference from the same motor with no flywheel is substantial, it is not marginal. You have to experiment on the turntable you are using. A small motor driving the massive platter trough a dedicated controller gave the best speed stability, but the large motor with flywheel has a much better sound in every parameter.

 

[YNWaN]

But I would argue that that is ultimately because the motor should be the master (not inherently but because it is active and it is difficult for the passive to override the active) and, in the case you cite, the flywheel is overcoming the dominance of the platter. The same could be achieved, in what I would argue is a more elegant manner, by deleting the flywheel and altering the balance between the platter mass and the motor drive characteristics.

 

[Lagonda]

But I would argue that that is ultimately because the motor should be the master (not inherently but because it is active and it is difficult for the passive to override the active) and, in the case you cite, the flywheel is overcoming the dominance of the platter. The same could be achieved, in what I would argue is a more elegant manner, by deleting the flywheel and altering the balance between the platter mass and the motor drive characteristics.

You have simply not heard the difference a flywheel makes, it is the micro cogging buffer effect that makes the biggest difference, but of coarse having sufficient platter mass for constant inertia and a low friction bearing is part of the equation too.

 

[YNWaN]

You have simply not heard the difference a flywheel makes, it is the micro cogging buffer effect that makes the biggest difference, but of coarse having sufficient platter mass for constant inertia and a low friction bearing is part of the equation too.

A valid point but I could argue the same with equal validity. Essentially your argument boils down to me not having your experience, but nor do you have mine. Anyway, if it is down to one persons opinion being worth more than another’s I will bow out now and leave the thread to you and others.

 

[Lagonda]

A valid point but I could argue the same with equal validity. Essentially your argument boils down to me not having your experience, but nor do you have mine. Anyway, if it is down to one persons opinion being worth than another’s I will bow out now and leave the thread to you and others.

Certainly, opinion or taste, i have heard many "UK type" TT's and none have really tickled my fancy, with the exception of the Townshend Reference, it had a heavier platter than most. They just never have the heft and tonal solidity that i have heard from the best air-bearing heavy platter designs.

 

[Vienna]

The problem with the opinions expressed on forums (in general, not specifically this one) is that they are inherently based on people’s experience with owning whole products. By that I mean they are unable to separate the motor from the rest of the turntable, or if they are, it has other elements attached to it as part of the package. This isn’t a criticism, it is the nature of buying solutions from manufacturers. What I think we all know is that ‘everything matters’, at least to some extent . So I am saying we need to consider every element and how it interacts with every other element. What is unusual in turntable is that whilst they are quite simple mechanisms in terms of the elements used, those elements interact in a very complex manner and are often asked to perform disparate roles simultaneously (rather than discreetly). So, for example, the precise distance the motor is from the platter makes a significant difference, the way the pulley is attached to the motor shaft. In a DD the way the bearing is integrated, the way the motor is shielded, the way the logic of the CFL is applied etc. Differ t compromises, but related ones, for each system - different balances of importance/relevance and how easy they are to address.

The problem is not the opinions expressed in forums, based on people’s experience with owning whole products. After all this is one of the reasons that forums were made for.

I think that we will all agree that the real issue is that nowadays, the turntables designers (at least the most of them) cannot and are unable to separate the different elements of a turntable and how they interact together. The most of the today produced turntables is a hodgepodge of OEM elements originally made for different purpose and not for turntables (e.g. motors, drive belts , controllers ).

And those few designers, who can separate and actually understand, how the different elements are interacting together, are those who have delivered (-ing) turntables built with real specs, great sound and precise stable speed.

These pieces are the ones which stand the test of time too.

I remember an article which I read some months ago. The writer at the end concluded : QUOTE ...But whom wants a manufacturer possibly fool, who isn´t even capable of designing a decent control system for a motor and a capable motor, but needs to source them from a banal OEM, Who has designed them for ventilators....UNQUOTE

 

[morricab]

You have simply not heard the difference a flywheel makes, it is the micro cogging buffer effect that makes the biggest difference, but of coarse having sufficient platter mass for constant inertia and a low friction bearing is part of the equation too.

If that is the case then using a motor that doesn’t cog, like the Brinkmann sinus, would eliminate the advantage of using the flywheel and simplify the problem again, no?

 

[morricab]

Certainly, opinion or taste, i have heard many "UK type" TT's and none have really tickled my fancy, with the exception of the Townshend Reference, it had a heavier platter than most. They just never have the heft and tonal solidity that i have heard from the best air-bearing heavy platter designs.

The Voyds with three Papst external rotor motors (I think these are tape capstan motors) and split phase power supply delivered a very hefty and powerful sound. In the end it was a bit noisy but man did the sound have punch and power.

 

[Lagonda]

If that is the case then using a motor that doesn’t cog, like the Brinkmann sinus, would eliminate the advantage of using the flywheel and simplify the problem again, no?

To be honest Brad, i am not a engineer and anything i say is speculation based on the experience i have made focusing on my own TT, maybe there is always some micro fluctuations going on when electrical power is converted to rotational force in a motor ? Maybe the flywheel smoothes this power transfer, maybe it is purely for torque enhancement on the Brinkmann ? It seems to be well engineered with just the right controller for just the right custom built motor, that includes a flywheel. The Voids, and later the early Audio Note ( they bought the rights) use 3 of the smaller Pabst synchronous AC motors that look a lot like the the large ones. When i was trying to locate the large Pabst i could not find any for sale and resorted to studying pictures of the internals of R2R recorders from the 60's and 70's. Tandberg, Grundig, Telefunken, Revox,Studer and weird and rare Eastern European, French and Belgian machines. Thousand of picture, inside a Danish Bang & Olufsen machine i found something that looked right Being in Denmark, i was fast able to find a machine sitting in an attic about 50 km away for sale. I was really disappointed when i dissected the machine and found the small motor used in the Void inside, it runs very speed stable and is better than the Hurst motor my TT was originally equipped with, but not really in the league of the large Pabst motors. Sometime later i read a 10 year old thread in a German specialist forum where someone talked about having a spare Pabst motor, i joined the forum and contacted the guy. He was not sure he had it anymore, but looked in his garage and found it ! That is how i found my AS 2000/TechDas Zero Pabst motor, it is not NOS but runs and sounds great. The Studer Pabst motor with a large built in flywheel i use sounds even better, at some time in the future i will have a large flywheel built and hear it the way it is used in those reference turntables

 

[Lagonda]

For some perspective of size. From left Original Hurst motor, small Pabst, large Pabst and small flywheel Studer. Second picture is small flywheel Studer next to large flywheel model. And installed !