Natural Sound

[PeterA]

Slip between the LP and platter, if it exists, must be extremely small and easily corrected with record clamps or vacuum hold down. Even without those, there is significant surface area and friction so I doubt it could even be measured.

The most significant factor affecting platter (LP) speed on belt drive tables is belt creep; unlike belt slippage which can be cured with proper tension, belt creep is a necessary byproduct of using a smooth belt and cannot be eliminated entirely, though it can be reduced. Belt creep is caused by the unequal tension on either side of an elastic belt.

Tables with subplatters suffer from increased belt creep because the limited contact area requires higher tension in the belt which exacerbates the problem.

Thank you Bill for contributing to this thread. I’ve often wondered about why the motor drive pulley is so small on most turntables. Is it because it would require a more more robust motor to drive a larger pulley or is it because there is some advantage to having a smaller diameter drive pulley? I would think that contact area would be increased with a larger pulley which would reduce belt creep. It would also increase inertia perhaps making the motor more stable.

Do you have any thoughts about the diameter of a motor drive pulley? And what do you think about thread drive?

 

[Lagonda]

Thank you Bill for contributing to this thread. I’ve often wondered about why the motor drive pulley is so small almost to turn tables. Is it because we need some more robust motor to drive a larger pulley or is it because there is some advantage to having a smaller diameter drive pulley? I would think that contact area would be increased with a larger pulley which would reduce belt creep. It would also increase inertia perhaps making the motor more stable.

Do you have any thoughts about the diameter of a motor drive pulley? And what do you think about thread drive?

Peter i think the pulley size is very much dictated by the speed of the motor. Most TT motors where made for other applications originally, making them run a platter at 33,33 rpm becomes a function of pulley size and controller. I think the small pulley size is a necessity more than a choice, most motors don't run well far outside their intended target speed.

 

[microstrip]

Peter i think the pulley size is very much dictated by the speed of the motor.

Exactly. Turntable designers operate the motor at the point where they consider optimum, considering speed, torque, its fluctuations and noise.

Most TT motors where made for other applications originally, making them run a platter at 33,33 rpm becomes a function of pulley size and controller. I think the small pulley size is a necessity more than a choice, most motors don't run well far outside their intended target speed.

Disregarding very cheap turntables, designers have such a choice of available motors that they can pick what they want, according to their views. But for example some high quality DC motors, such as the Maxon's, operate around 1500/2000 RPM and need a much smaller pulley than the typical synchronous that operates typically at 250/300 RPM.

 

[Phoenix Engineering]

Thank you Bill for contributing to this thread. I’ve often wondered about why the motor drive pulley is so small on most turntables. Is it because it would require a more more robust motor to drive a larger pulley or is it because there is some advantage to having a smaller diameter drive pulley? I would think that contact area would be increased with a larger pulley which would reduce belt creep. It would also increase inertia perhaps making the motor more stable.

Do you have any thoughts about the diameter of a motor drive pulley? And what do you think about thread drive?

It's difficult to explain without a bit of math. The speed of the motor (and therefore the pulley ratio) is: Ms=Freq x120/poles where Ms= motor speed in RPM. Frequency is fixed at 50 or 60 Hz depending on where you are, so the number of poles in the motor is the main determinate of motor speed. You could theoretically design a motor to run at almost any speed (within limits) by changing the number of poles (always an even number). Changing the speed of the motor also affects the torque produced.

The available power from the motor to spin the platter is: P=(2*Pi*t*RPM)/60 where t=torque . Comparing 2 motors of the same power but with different speeds (300 RPM vs 600 RPM) means the torque doubles at the lower speed and some mfrs claim this is a benefit, but it also requires the pulley to double in size so the mechanical advantage with the lower speed motor is half that of the higher speed motor, so there is essentially no gain by using a lower speed motor (the power delivered to the platter is the same whether the motor is 300 or 600 RPM if the motors have the same power rating).

An AC synch motor has two speeds: Zero and 100% so the motor starts at full speed very quickly when powered on. The smaller diameter pulley will have an easier time starting the platter moving than a larger pulley (slower speed motor) because of the higher mechanical advantage. The closest analogy would be trying to start a car moving from a dead stop in 1st gear (600 RPM) vs 2nd gear (300 RPM); the latter will experience much more burn-out on the belt (clutch). The best solution to this problem is to start the motor at a much slower speed and ramp up to the final speed to help overcome the inertia of the platter. Few motor controllers do this properly. For low voltage motors, this is not as much of a problem, but for motors designed to run at line voltages, this gets complicated because most controllers regenerate a low voltage sine wave and step the voltage up via a transformer which is designed to operate at 50-60Hz; you cannot start a system like this at 5Hz and expect it to work very well. The obvious solution is to create a HV directly coupled amp with no step up transformer that can operate from a few Hz to 100Hz+. It's doable, but not trivial, especially at high power.

A smaller diameter pulley will potentially have more slippage (which can be cured with proper tension), but I've never run any tests to see if there any difference in the amount of belt creep vs diameter. In theory, there should not be, except that the smaller diameter pulley might require more tension and therefore more belt creep. No such thing as a free lunch.

The pulley is low mass and small diameter so it does not have much effect on motor inertia (I=m*r^2/2). Adding a heavy, larger diameter flywheel to the motor will have a positive effect on motor speed stability.

Thread drive vs belt drive is another study in trade-offs. The thread is less elastic than most belts, so less belt creep, but more prone to slippage and getting the tension correct is more critical. Since thread is less compliant, it has the ability to transmit vibration from the motor to the platter more easily. Belt creep is a concern, but it can be compensated for and dealt with effectively, so the downside of using thread may outweigh the upside. YMMV.

 

[Tango]

What's also left out is how constant does platter speed needs to be, we certainly don't need 3 decimal points. How much variation with 2 decimal points is really audible?

My ears are not as golden as many. I don't hear any difference when my speed is between 33.330 to 33.337. My speed is very stable, doesn't keep zigzag running back and forth between the last decimal though. I think 3 decimal is only good to check the stability. So I don't bother adjusting the speed to be accurate to the last decimal.

 

[bonzo75]

My ears are not as golden as many.

You think so only because you keep benchmarking against Gian and me. Benchmark against others and you will feel better about yourself

 

[Tango]

You think so only because you keep benchmarking against Gian and me. Benchmark against others and you will feel better about yourself

you have no system. Give me your records. What good is there to have a bullet but no gun.

 

[bonzo75]

you have no system. Give me your records. What good is there to have a bullet but no gun.

I can't lend you my ears. Imagine giving you the gun with no steady arm

 

[andromedaaudio]

you have no system. Give me your records. What good is there to have a bullet but no gun.

How would it ever be possible for him to comment on a systems listening fatigue factor as he only spends a couple of hours / days / hours with a system

 

[bonzo75]

How would it ever be possible for him to comment on a systems listening fatigue factor as he only spends a couple of hours / days / hours with a system

It is unfortunate you don't know how

 

[XV-1]

you have no system. Give me your records. What good is there to have a bullet but no gun.

Ked, do you own records?

Interesting fact, I don't believe in slippage itself caused by the stylus, however every now and then I get slippage playing records on my SP10mk3.
I use a micro Seiko cu180 gun metal mat - sometimes if the record is dished at the right angle ( up from the platter surface) I will have obvious speed fluctuations in playing that record.

The dished record combined with the huge starting torque of the SP10mk3 creates the slippage easily.

Outside of this type occurrence, I don't feel vinyl slippage is a real thing.

 

[tima]

Let's just say that after reading Alvin's paper there's quite a bit that I disagree with and important elements of belt design that he's conveniently left out. Of course the elephant in the room isn't how many times you measure the speed and how many adjustments you make to reach a numerical constant that he avoids discussing. What's also left out is how constant does platter speed needs to be, we certainly don't need 3 decimal points. How much variation with 2 decimal points is really audible? One thing that I do agree with which he touches on is the quality of the motors currently available for belt drive use, they present their ow set of challenges that need to be addressed and they're not in many designs currently.

Dear David, It is no surprise that you disagree with Lloyd's critique of belt drive - you each use fundamentally different approaches to turntable design. High mass steel(?) platter and plinth, strong motor, and belt driven vs light-weight platter, low low torque power motor and a double wall highly damped carbon fiber plinth. Radically different.

Apart from assessment of motor and platter control differences, the GPA approach and Lloyd's claims for his products do not depend on his critique of belt drive tables. Debate on theoreticals and philosophies of which approach is superior can be had. Each of you has achieved what you've done using the designs and techniques that you've used and the results of doing so speak for themselves. I have tremendous respect for both efforts. Presumably neither will dispute the measurements each claims for his product - this is not placing measurement in some hierarchy of value, but simply acknowledging the technical claims for each.

ddk: "What's also left out is how constant does platter speed needs to be, we certainly don't need 3 decimal points. How much variation with 2 decimal points is really audible?"

This is where it gets really interesting. You ask perfectly reasonable questions - the same asked by many turntable end-users, particulary those in the upper end of the market whu seek to come closer to whatever they see as perfection or value. Many, most people indeed say, "well I don't expect to hear some small percentage difference in stable accuracy ... and as far as I know, I don't. Okay. It's probably the rare scenario where multiple highly acclaimed turntables are compared for sonic differences under identical conditions. Whether relative stable accuracy can be isolated in listening tests from all other factors is questionable at best.

And we can leave cost out of the comparison entirely, but eventually it will remain a factor. While almost everyone pays homage to the notion of 'merit only' - at least in principle - I do not believe people who can afford whatever they choose and believe they choose ito the best can actually remove that entirely from their belief system. jmo

I admit to not having the experience of yourself or others who have evaluated many purportedly 'best' or top tables or the experience of designer/manufacturers. Several of our fellow audiohpiles have marched through several over time and we find their experience interesting.

As to the question of how much stable accuracy really does matter, I can only speak for my own experience, which does not include high value ($150k+ ?) tables. That is based on hearing the extraordinarily stablely accurate Monaco 1.5 and the Monaco 2.0 that exceeds it sonically (imo) by a significant margin. I won't bore with recounting the specs for either 'table, the 2.0 has an entirely new drive system. But I know what I heard comparing the two under precisely identical configurations. "Switching to the 2.0 from the already accurate, stable and quiet 1.5 was a vivid, literally goosebump-raising experience that left me joy-stricken and bewildered at the differences I heard. How was this possible? I only switched turntables - ... What was new was the source signal itself." There may be a bare handful of people who have made that same comparison and best I as understand, they agree with my assessment - think of them what one may. If I had not heard the differences I did I would not have said so in publication.

In a nutshell I know - as firmly as I believe I can know - that small differences in decimal points or ppm (relatively large between the two tables measurement wise) make a truly significant sonic difference. It bothers me not a whit that others don't believe such a difference exists or can exist or is not audible to them. That has nothing to do with others enjoying the tables they have.

I would absolutely love to hear a non-competitive discussion between yourself and Alvin about what makes your products successful and why you each choose the route taken. For educational purpose - so that we the non-designer, non-manufacturing end users can learn about them.

eidt: typos

 

[tima]

I inherited 1000 LPs recently and will clean, sort, and listen to them this winter when I have more time for audio.

WoW - how wonderful is that! Sounds like you might enjoy a high volume high throughput SOA record cleaning system.

 

[ddk]

Dear David, It is no surprise that you disagree with Lloyd's critique of belt drive - you each use fundamentally different approaches to turntable design. High mass steel(?) platter and plinth, strong motor, and belt driven vs light-weight platter, low low torque power motor and a double wall highly damped carbon fiber plinth. Radically different.

Apart from assessment of motor and platter control differences, the GPA approach and Lloyd's claims for his products do not depend on his critique of belt drive tables. Debate on theoreticals and philosophies of which approach is superior can be had. Each of you has achieved what you've done using the designs and techniques that you've used and the results of doing so speak for themselves. I have tremendous respect for both efforts. Presumably neither will dispute the measurements each claims for his product - this is not placing measurement in some hierarchy of value, but simply acknowledging the technical claims for each.

ddk: "What's also left out is how constant does platter speed needs to be, we certainly don't need 3 decimal points. How much variation with 2 decimal points is really audible?"

This is where it gets really interesting. You ask perfectly reasonable questions - the same asked by many turntable end-users, particulary those in the upper end of the market whu seek to come closer to whatever they see as perfection or value. Many, most people indeed say, "well I don't expect to hear some small percentage difference in stable accuracy ... and as far as I know, I don't. Okay. It's probably the rare scenario where multiple highly acclaimed turntables are compared for sonic differences under identical conditions. Whether relative stable accuracy can be isolated in listening tests from all other factors is questionable at best.

And we can leave cost out of the comparison entirely, but eventually it will remain a factor. While almost everyone pays homage to the notion of 'merit only' - at least in principle - I do not believe people who can afford whatever they choose and believe they choose ito the best can actually remove that entirely from their belief system. jmo

I admit to not having the experience of yourself or others who have evaluated many purportedly 'best' or top tables or the experience of designer/manufacturers. Several of our fellow audiohpiles have marched through several over time and we find their experience interesting.

As to the question of how much stable accuracy really does matter, I can only speak for my own experience, which does not include high value ($150k+ ?) tables. That is based on hearing the extraordinarily stablely accurate Monaco 1.5 and the Monaco 2.0 that exceeds it sonically (imo) by a significant margin. I won't bore with recounting the specs for either 'table, the 2.0 has an entirely new drive system. But I know what I heard comparing the two under precisely identical configurations. "Switching to the 2.0 from the already accurate, stable and quiet 1.5 was a vivid, literally goosebump-raising experience that left me joy-stricken and bewildered at the differences I heard. How was this possible? I only switched turntables - ... What was new was the source signal itself." There may be a bare handful of people who have made that same comparison and best I as understand, they agree with my assessment - think of them what one may. If I had not heard the differences I did I would not have said so in publication.

In a nutshell I know - as firmly as I believe I can know - that small differences in decimal points or ppm (relatively large between the two tables measurement wise) make a truly significant sonic difference. It bothers me not a whit that others don't believe such a difference exists or can exist or is not audible to them. That has nothing to do with others enjoying the tables they have.

I would absolutely love to hear a non-competitive discussion between yourself and Alvin about what makes your products successful and why you each choose the route taken. For educational purpose - so that we the non-designer, non-manufacturing end users can learn about them.

eidt: typos

Dear Tim,

I wasn't trying to argue between the drive types merely pointing out that Monaco's white paper isn't really that white. There are missing facts and claims are made without providing any data.

Your comment on cost is a very valid point and one that people consider when making a purchase. Fortunately or unfortunately in this hobby price and quality don't always go hand in hand but there are target markets that manufacturers consider when designing products.

david

 

[tima]

I wasn't trying to argue between the drive types merely pointing out that Monaco's white paper isn't really that white. There are missing facts and claims are made without providing any data.

Understood. It is an older treatise based on his 1.0 design and knowing him I'm sure he would offer updated information today.

I do give Alvin credit for his willingness to publish what he did. He went to the edge of proprietary info.

 

[bazelio]

Is there more to the 1.5 to 2.0 evolution than additional thousandths of a percentage in speed accuracy improvement? I'm curious as to how many variables are in play here. It could be materials, chassis design update, damping, etc, etc. Speed accuracy improvement is the headline, but may very well not be a first order contributor to cause and effect.

 

[microstrip]

My ears are not as golden as many. I don't hear any difference when my speed is between 33.330 to 33.337. My speed is very stable, doesn't keep zigzag running back and forth between the last decimal though. I think 3 decimal is only good to check the stability. So I don't bother adjusting the speed to be accurate to the last decimal.

Do you hear any difference between 33.33 and 33.30?

 

[rando]

Peter, as Micro just alluded, teaching someone to use fine judgement in physically tuning a piece of equipment is not the same as them having arrived at when this thin of adjustments are necessary.

Still a bit woozy at thought of cleaning roughly a thousand records. Two thousand sides over the coming months would certainly give plenty of insight into system behaviors though.

 

[PeterA]

Peter, as Micro just alluded, teaching someone to use fine judgement in physically tuning a piece of equipment is not the same as them having arrived at when this thin of adjustments are necessary.

Still a bit woozy at thought of cleaning roughly a thousand records. Two thousand sides over the coming months would certainly give plenty of insight into system behaviors though.

Hi Rando, I simply posted those videos to demonstrate that some tables, and particularly this 40 year old vintage table, can hold a pretty stable and accurate speed. I've seen well regarded contemporary tables not able to do so. I once started a thread asking people to post publicly results of other tables using the Sutherland TimeLine. The thread died quickly as no one took up the challenge. A WBF member from Germany suggests taking the TimeLine for testing contenders if one is in the market for a new turntable. I think it is an interesting idea. I've heard reports of dealers not allowing clients to bring that device into their shops.

One friend let me put it on his table and the results were terrible. He was using the VPI motor controller. He concluded the TimeLine is flawed. He theorized that the weight of the unit placed on the spindle of his turntable changed the performance of the table, or that the strobe is inaccurate. This is one reason I wanted to show both the TimeLine and the RR tachometer working concurrently to confirm accuracy of both devices and that the speed does not change when the Timeline is placed on the spindle and removed, at least not on the Micro Seiki.

I think speed is a primary criteria for a turntable, and it is indeed audible at some measure of accuracy and consistency. Tim commented about this regarding his Grand Prix Monaco 2.0. What degree of accuracy and consistency or how "thin of adjustments are necessary" or audible is a debatable subject as others have pointed out.

Regarding the records, the first step is to sort them for titles I might like. That will surely lesson the task. One collection is from my grandfather, and there appear to be some very old early momo LPs. They don't appear to have been played since the 50s or 60s. There is one copy of Peter and the Wolf that was given to my uncle for Christmas by his Godfather when he was ten years old in 1946.

 

[Tango]

Do you hear any difference between 33.33 and 33.30?

I never tried. My experiences were not experiment. They were experiences occurred during and after replacing the belt of AS2000. My other experiences on speed variation were through Kronos and AF3P but those were big margin variation which is easy to hear and resulted from a malfunction of motor control.