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The Importance of Anti-skate, Do decks without it skew left?
Knowzy
post Oct 1 2008, 22:49
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In our last conversation, we came up with three increasingly strignent criterium for selecting a decent USB turntable:
  1. Ceramic cartridge never!
  2. Anti-skate
  3. Direct drive (remember, these are sub-$1,000 turntables)
I'm having particular trouble explaining the anti-skate requirement.

Here's what I'm hoping HA can answer:
  • Do turntables without anti-skate, such as the Audio-Technica LP2D-USB, truly have no compensation and ride the inner groove like a surfer catching a wave?
  • Someone at the Vinyl Engine suggested that the weight of the "high mass" tonearms found on such TT's essentially force the stylus into the middle of the groove. Thoughts on this?
I need some compelling reasons to choose a deck with anti-skate, especially for people who don't plan on replacing the cart.

There's already a good reason to choose a TT without anti-skate: Newbies don't need to learn how to balance their tonearm.

Thanks!
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cliveb
post Oct 2 2008, 08:54
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QUOTE (Knowzy @ Oct 1 2008, 22:49) *
In our last conversation, we came up with three increasingly strignent criterium for selecting a decent USB turntable:
[*]Ceramic cartridge never!
[*]Anti-skate
Agreed.

QUOTE (Knowzy @ Oct 1 2008, 22:49) *
[*]Direct drive (remember, these are sub-$1,000 turntables)
Where does that requirement come from? There are plenty of decent belt drive turntables below $1000. There is no reason to believe that belt drive is inferior to direct drive at any particular price point.

Indeed, IMHO a cheap direct drive it likely to be worse than a similarly priced belt drive. Direct drive turntables require high torque motors with excellent speed stability. Such motors are not cheap. Belt drive can get away with fairly inexpensive low torque motors, because the belt/platter provides a mechanical smoothing buffer against speed instability.

QUOTE (Knowzy @ Oct 1 2008, 22:49) *
[*]Do turntables without anti-skate, such as the Audio-Technica LP2D-USB, truly have no compensation and ride the inner groove like a surfer catching a wave?
Just because a turntable like this has no user adjustable anti-skating doesn't necessarily mean it has none. Given that this is an "all-in-one" package, the tracking weight and antiskating could well be factory-preset.

That said, the device looks cheap and plasticy to me. Audio Technica have a solid reputation for pickup cartridges, but they do not have a history of good turntable production. This product looks to me like they decided there was a bandwagon (cheap USB turntables) they needed to jump on.
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Soap
post Oct 2 2008, 11:14
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QUOTE (cliveb @ Oct 2 2008, 03:54) *
Indeed, IMHO a cheap direct drive it likely to be worse than a similarly priced belt drive. Direct drive turntables require high torque motors with excellent speed stability. Such motors are not cheap. Belt drive can get away with fairly inexpensive low torque motors, because the belt/platter provides a mechanical smoothing buffer against speed instability.

This argument just doesn't make sense to me.
1 - Regarding torque requirements:
Both direct drive and belt drive are attempting to accelerate the same mass against the same drag forces. Why would a direct drive motor need more torque? If anything a belt drive system actually has more drag sources than a direct drive system.

2 - Regarding belt/platter providing a "buffer" system.
Again, assuming equal platter mass in both systems the primary mechanical buffer is going to be the identical inertia of the platters.

I clearly could be wrong, but I would like to know how I am wrong.


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cliveb
post Oct 2 2008, 16:25
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QUOTE (Soap @ Oct 2 2008, 11:14) *
This argument just doesn't make sense to me.
The requirement for either system is to rotate the platter at a constant 33.3 rpm.

In a direct drive turntable, the motor itself must rotate at that speed (because the centre spindle of the platter is the armature of the motor), and any variation from it has to be detected and corrected as quickly as possible. There are two approaches to this:
1. Use a heavy platter to give a good flywheel effect. The problem here is that the heavier the platter, the higher the motor torque needs to be to be able to correct any speed instabilities.
2. Use a light platter. This allows a lower torque (and cheaper) motor, but the downside is that you get less flywheel effect to start with, and so there will be more speed instabilities to be corrected.

In a belt drive system, provided you don't care how long it takes for the platter to initially get up to speed, you can use a platter as heavy as you like, and therefore take advantage of as much flywheel effect as you wish.

I'm not trying to argue against direct drive. It's possible to make a good turntable using either system. (But for a given level of performance, the engineering required usually costs more for direct drive). All I wanted to do was question why the OP seemed set against belt drive.
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Posts in this topic
- Knowzy   The Importance of Anti-skate   Oct 1 2008, 22:49
- - Axon   QUOTE (Knowzy @ Oct 1 2008, 16:49) Here...   Oct 1 2008, 23:12
|- - Knowzy   QUOTE (Axon @ Oct 1 2008, 15:12) QUOTE (K...   Oct 1 2008, 23:34
|- - 2Bdecided   QUOTE (Axon @ Oct 1 2008, 23:12) The most...   Oct 2 2008, 11:48
|- - WmAx   QUOTE (2Bdecided @ Oct 2 2008, 06:48) P.S...   Oct 2 2008, 16:19
- - cliveb   QUOTE (Knowzy @ Oct 1 2008, 22:49) In our...   Oct 2 2008, 08:54
|- - Soap   QUOTE (cliveb @ Oct 2 2008, 03:54) Indeed...   Oct 2 2008, 11:14
|- - cliveb   QUOTE (Soap @ Oct 2 2008, 11:14) This arg...   Oct 2 2008, 16:25
- - Axon   So, I haven't had a whole lot of experience in...   Oct 2 2008, 17:25
|- - WmAx   QUOTE (Axon @ Oct 2 2008, 12:25) So, I ha...   Oct 2 2008, 17:55
|- - Axon   QUOTE (WmAx @ Oct 2 2008, 11:55) Time to ...   Oct 2 2008, 22:33
|- - WmAx   QUOTE (Axon @ Oct 2 2008, 17:33) QUOTE (W...   Oct 2 2008, 22:49
|- - Axon   QUOTE (WmAx @ Oct 2 2008, 16:49) I looked...   Oct 3 2008, 07:24
|- - WmAx   QUOTE (Axon @ Oct 3 2008, 02:24) Besides ...   Oct 3 2008, 07:37
|- - honestguv   QUOTE (Axon @ Oct 3 2008, 08:24) QUOTE (W...   Oct 3 2008, 10:40
- - Knowzy   My anti-skate questions are answered, so let me ge...   Oct 2 2008, 22:13
|- - botface   QUOTE (Knowzy @ Oct 2 2008, 22:13) My ant...   Oct 3 2008, 07:10
|- - Knowzy   QUOTE (botface @ Oct 2 2008, 23:10) QUOTE...   Oct 3 2008, 18:54
|- - 2Bdecided   QUOTE (Knowzy @ Oct 3 2008, 18:54) Let...   Oct 6 2008, 16:01
- - Paul Sanders   I think anti-skate is very important. I made the ...   Oct 3 2008, 19:03
- - Knowzy   QUOTE (cliveb @ Oct 2 2008, 00:54) QUOTE ...   Oct 5 2008, 21:01
- - Knowzy   QUOTE (2Bdecided @ Oct 6 2008, 08:01) Min...   Oct 6 2008, 20:45


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