In praise of idlers

[Alrainbow]

The origin of the idler magic? its that direct connection between a strong torque motor and heavy platter. No belts streching and wobble from stylus drag.

The torque of a typical 15w idler motor corresponds to the inertia of a 200kg platter!

Further, compared to direct drive, the torque ripple of the idler is much smaller and more frequent due to higher rotational speed. The heavier the platter, the more the torque ripple will be eliminated. And no electrical feedback system is needed.

My guess is that the kuzmas come close to idler performance due to that stiff plastic belt that locks the platter to the (big) motor.

Im new to idler world (restored TD124) but cant agree on your belt stretching idler to platter thesis ..

Actually im learning the worst thing to do in audio is to hold on to assumptions and stiff Ideology..

Tubes vs SS , analog vs digital , class D vs A etc , horns vs box and planers, somehow someone somewhere gets these audio anathemas to work , well somewhat ..

Anyway , I hear merits and differences in TT drives chosen , some inherent most setup and system dependent..

So far im ahead with belts vs DD and idler drive , Note ..! Im not attributing it to drive systems , i’m well aware of the pitfalls in TT setups , arm matching, cart tracking , etc

I’m not Odin ...

 

[ferrari275]

Alrainbow

Im new to idler world (restored TD124)

So far im ahead with belts vs DD and idler drive , Note ..! Im not attributing it to drive systems , i’m well aware of the pitfalls in TT setups , arm matching, cart tracking , etc

IMHO/IME a restored Thorens TD124 hybrid belt/idler will not yield the same results as a properly executed idler drive, as it is a different animal.

 

[ferrari275]

jespera

The origin of the idler magic? its that direct connection between a strong torque motor and heavy platter. No belts streching and wobble from stylus drag.

The torque of a typical 15w idler motor corresponds to the inertia of a 200kg platter!

The most common vintage single phase AC induction motors are low torque with moderately high centrifugal rotational inertia. I believe most can agree about a heavier platter having some distinct advantages.

Torque Calculator

 

[microstrip]

Im new to idler world (restored TD124) but cant agree on your belt stretching idler to platter thesis ..

The small belt of the TD124 stretches more than the large belt of the TechDas AF1P ...

 

[jespera]

The most common vintage single phase AC induction motors are low torque with moderately high centrifugal rotational inertia. I believe most can agree about a heavier platter having some distinct advantages.

Torque Calculator

That is at the axel of the motor. But thats irrelevant. What counts is the power and the rotational speed of the platter.
The formula for torque is

T = P/R

where P = power = 15 W and R = 33/60 s^-1 with units Nm.

The inertia (torque) of the platter is the rotational energy

T = 0.5 m v^2

where m is the mass and v is the rotational speed = 33/60 s^-1 * (2 pi 0.15m).

Insert the numbers and isolate for m and you get the result.

If you want to make a bet about it, I only take idlers as collateral.

Jesper

 

[jespera]

The small belt of the TD124 stretches more than the large belt of the TechDas AF1P ...

That is incorrect. Even if the two belts have the same compliance the force on the td124 belt approx
33/60/(50/2) times lower than on the tech das belt. The reason for this is the gearing of the idler wheel.

Wanna bet your emt? You say you cant hear the difference anyways.

Jesper

 

[microstrip]

That is incorrect. Even if the two belts have the same compliance the force on the td124 belt approx
33/60/(50/2) times lower than on the tech das belt. The reason for this is the gearing of the idler wheel.

Wanna bet your emt? You say you cant hear the difference anyways.

Jesper

The belt of the TechDas has extremely low compliance - I think that it is a kevlar type belt, the original belt of the Thorens TD124 I have owned was very compliant - I would expect a factor of more than x 10 higher than the TechDas one. The ratio of the Thorens motor pulley to the idler pulley is about x 1/2 . Independently of forces there is a compliant belt in the transmission, it was my only point.

Anyway, I know which I preferred, it is what matters in this hobby. But I like both the EMT 927 and the TechDas AF1P, as well as the Forsell with the airbearing flywheel.

 

[jespera]

The belt of the TechDas has extremely low compliance - I think that it is a kevlar type belt, the original belt of the Thorens TD124 I have owned was very compliant - I would expect a factor of more than x 10 higher than the TechDas one. The ratio of the Thorens motor pulley to the idler pulley is about x 1/2 . Independently of forces there is a compliant belt in the transmission, it was my only point.

Anyway, I know which I preferred, it is what matters in this hobby. But I like both the EMT 927 and the TechDas AF1P, as well as the Forsell with the airbearing flywheel.

That's what it takes to solve engineering problems with materials: 20-45 times less compliance.

The presence of the belt on the td124 has always puzzled me. Incidentally, I find the the td124 to be less
metronomic than garrards and lencos. But it has a very nice flow to its presentation.
Despite, or maybe due to, the belt, the td124 is renowned for being difficult to get rumble free. Its the only
idler I have struggled with getting to run silently.

Yes, I agree its the preferences that matter.

 

[Alrainbow]

I dont see how you can get an idler to be as quite as belt drive , maybe a drive advantage BD is dependent on platter inertia and motor TQ after that its all win win for a BD , darker background etc ...

Just a bit more wait for speed lock ...

 

[Folsom]

TD124's have about as nice of speed consistency of any turntable ever made. I mean they're really good.

They have an internal breaking system that runs the entire time. I suspect that they used the belt to isolate/damp from that.

 

[microstrip]

(...) Despite, or maybe due to, the belt, the td124 is renowned for being difficult to get rumble free. Its the only idler I have struggled with getting to run silently. (...)

As far as I have read and verified , the only problem with the TD124 is that people use it, since its origin, with the wrong plinth that creates rumble. I think it is explained in the Joachim Bung book on the TD124 : "Swiss Precision: The Story of the Thorens TD 124 and Other Classic Turntables" . Or just ask David (DDK) he will be able to explain it much better than me!

 

[microstrip]

TD124's have about as nice of speed consistency of any turntable ever made. I mean they're really good.

They have an internal breaking system that runs the entire time. I suspect that they used the belt to isolate/damp from that.

Many idlers have drag systems to control speed, either magnetic (Foucault currents) or mechanical. I even know someone who does it tuning the viscosity of the oil bearing! We can bypass these systems just using an adjustable power supply. However, as you say we loose the intrinsic dampening of such systems. It is why turntables should be operated with the type of oil that comes from origin if we want them to sound as their designer wanted.

 

[jeff1225]

As my 401 project is coming together, I'm now thinking about external power supplies. Can I have your opinions on power supplies that keep the eddy break intact and and those that remove the eddy break.

Thank you in advance for your advice!

 

[Folsom]

As my 401 project is coming together, I'm now thinking about external power supplies. Can I have your opinions on power supplies that keep the eddy break intact and and those that remove the eddy break.

Thank you in advance for your advice!

Jeff, you want one of these. You don't need the type of power supply the AS2000 or others run because the Garrard motor is single phase, and the others are two phase. In other words you don't have to rewire the turntable like you would with a different type of motor.

The most important thing is an accurate consistent frequency along with power, that unit linked provides exactly that. The only addition I'd consider would be one of my Fo-Felix filters (with maybe an addition) to isolate it from the rest of the stereo.

There are other outboard supplies, IMO don't waste your money they're either inferior or do nothing else of any use besides make you turn you wallet further upside down. If one is seeking better sound through some sorta obscure magic besides consistent speed then they're looking in the wrong place.

 

[jespera]

Some people say the eddy break is an essential part of the idler magic. Here's a quite serious study:

https://electravolt.blogspot.com/2016/06/garrard-301.html#comment-form

Dont know if he can be trusted though. He has recently flipped and is now marketing a plastic platter version of the verdier.

Schopper, Hanze hifi and others suggest to run the td124's at approx 200V ie 10-15% down. The point of that is apparently to reduce
the use of the eddy brake, though not necessarily completely take it out. According to this piece at least:

https://positive-feedback.com/reviews/hardware-reviews/the-hanze-hifi-hat-turntable-power-supply/2/

Some of the lenco guys are combining regulated power supplies with a slow servo.

It is worth noting that, at least nominally, voltage on the european continent (thorens/lenco land) has been increased
from 220v to 230v and voltage in uk (garrard land) has been decreased from 240v to 230v, since these fine machines were
constructed.

I dont know if we in our new found freedom from each other will change that back again ... ?

 

[Mike Lavigne]

I dont see how you can get an idler to be as quite as belt drive , maybe a drive advantage BD is dependent on platter inertia and motor TQ after that its all win win for a BD , darker background etc ...

Just a bit more wait for speed lock ...

i think it takes a fresh no holds bared over-the-top approach to the whole idler design to be able to have the parts in place to accomplish 'belt-drive' levels of quiet. if you take a vintage idler and go about improving the basic design you can make a big difference but there is a limit to how far you can go. this is assuming you start out with a standard model vintage idler.

the Saskia model two idler is such a modern over-the-top design, and to my ears it's noise levels rival my super quiet CS Port belt drive. but it has a motor and plinth design, as well as a precision and materials level beyond any other idler i've seen. it is quiet.

 

[Folsom]

Some people say the eddy break is an essential part of the idler magic. Here's a quite serious study:

https://electravolt.blogspot.com/2016/06/garrard-301.html#comment-form

Dont know if he can be trusted though. He has recently flipped and is now marketing a plastic platter version of the verdier.

Schopper, Hanze hifi and others suggest to run the td124's at approx 200V ie 10-15% down. The point of that is apparently to reduce
the use of the eddy brake, though not necessarily completely take it out. According to this piece at least:

https://positive-feedback.com/reviews/hardware-reviews/the-hanze-hifi-hat-turntable-power-supply/2/

Some of the lenco guys are combining regulated power supplies with a slow servo.

It is worth noting that, at least nominally, voltage on the european continent (thorens/lenco land) has been increased
from 220v to 230v and voltage in uk (garrard land) has been decreased from 240v to 230v, since these fine machines were
constructed.

I dont know if we in our new found freedom from each other will change that back again ... ?

Power factor these days is bad, which might explain some of the results form fiddling with voltages etc. You can also just rock something that doesn't have bad power factor.

 

[jeff1225]

Power factor these days is bad, which might explain some of the results form fiddling with voltages etc. You can also just rock something that doesn't have bad power factor.

Reducing the power seems to have benefits with reduced motor vibration, this is independent of any power grid issues.

 

[microstrip]

Jeff, you want one of these. You don't need the type of power supply the AS2000 or others run because the Garrard motor is single phase, and the others are two phase. In other words you don't have to rewire the turntable like you would with a different type of motor.

The most important thing is an accurate consistent frequency along with power, that unit linked provides exactly that. The only addition I'd consider would be one of my Fo-Felix filters (with maybe an addition) to isolate it from the rest of the stereo.

There are other outboard supplies, IMO don't waste your money they're either inferior or do nothing else of any use besides make you turn you wallet further upside down. If one is seeking better sound through some sorta obscure magic besides consistent speed then they're looking in the wrong place.

Folson,

Does this unit allow us to adjust voltage? I could not find any specifications of the Athena.

 

[Folsom]

Folson,

Does this unit allow us to adjust voltage? I could not find any specifications of the Athena.

115/230v switchable. I bet they are a small nudge away from being able to add a switch for reducing the power by small increments. That would be useful for tube amplifiers that are vintage.

Just to confirm I'd only use this on single phase motors.