Disk Clamping - Which is best ?? - diyAudio
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Old 13th October 2007, 06:08 PM   #1
poynton is offline poynton  United Kingdom
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Default Disk Clamping - Which is best ??

Could someone explain exactly how a magnetic clamping device affects reproduction as opposed to a non-magnetic clamp (eg brass) ??

Andy
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Old 13th October 2007, 06:28 PM   #2
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Why do you assume it does ?
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Old 13th October 2007, 09:22 PM   #3
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I don't !

However, several 'experts' have stated that it does so I am asking for proof or otherwise.

Andy
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Old 13th October 2007, 09:46 PM   #4
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Hi Poynton, hi Rfbrw,

I hope you are not including me when you say 'experts'. The opposite is truer in my case...
It is only that my ears tell me that my ugly transport produces better sound when not using the powerful magnetic clamp that came stock with it. At least two other people seem to agree... but perception is tricky...I would not bet a finger for it

Quote:
I am asking for proof or otherwise.
Here I am lost. Why ask for proof if you can test it on your own?
The option of discarding it from known theory is risky, also.

I was warned by Void:
CD PRO 2 - The making of a high end CD Transport

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Try to avoid magnetic pucks, the rotating magnetic field seriously influences the tiny coils in the laser (focus and tracking errors, which means more corrections which increase jitter that can't be removed). Also any mechanical unbalance adds vibrations (increases jitter).
Observation-> hypothesis-> test...etc
Occidental view point.

Cheers,
M
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Old 13th October 2007, 10:08 PM   #5
poynton is offline poynton  United Kingdom
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Does the magnetic field rotate?
I seem to remember this coming up elsewhere.

I would imagine that the north (or south) pole of the magnet faces the metal disc with the other pole pointing into the air.

The magnet may rotate but in my mind, anyway, the field would remain constant. ( minor manufacturing faults disregarded.)

A constant non-changing field does not induce any current.

Andy
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Old 13th October 2007, 10:19 PM   #6
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Then, why worry?
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Old 13th October 2007, 11:23 PM   #7
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Quote:
Originally posted by poynton
Does the magnetic field rotate?
I seem to remember this coming up elsewhere.

I would imagine that the north (or south) pole of the magnet faces the metal disc with the other pole pointing into the air.

The magnet may rotate but in my mind, anyway, the field would remain constant. ( minor manufacturing faults disregarded.)

A constant non-changing field does not induce any current.
Why would you think the clamp effect is caused by magnetic field? It can equally well be mechanically induced, considering how clamping mechanism is implemeted in CD-Pro.

I was listening to Shigaraki with magnetic clamp and to me it sounded better than Flatfish with screw in acrylic clamp.
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Old 14th October 2007, 07:34 AM   #8
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Default Re: Disk Clamping - Which is best ??

Quote:
Originally posted by poynton
Could someone explain exactly how a magnetic clamping device affects reproduction as opposed to a non-magnetic clamp (eg brass) ??

Andy
I could easily have phrased this question the other way round.


Quote:
Originally posted by Peter Daniel


Why would you think the clamp effect is caused by magnetic field? It can equally well be mechanically induced, considering how clamping mechanism is implemeted in CD-Pro.

I was listening to Shigaraki with magnetic clamp and to me it sounded better than Flatfish with screw in acrylic clamp.
So what causes the difference ?
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Old 15th October 2007, 09:30 PM   #9
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Hi Andy,
Assuming there are no other unintentional effects, it should not matter. The clamp that couples the CD to the table will perform as required. Nothing more will make any difference.

As for magnetic clamps, the table forms the other half of the magnetic circuit. Therefore they are stationary with respect to each other. In this case, there will be no moving field to create eddy currents or any other effect. The CD itself is plastic an non-ferrous metal, so no effect there either. The main advantage is that the upper clamp disconnects completely from everything else, so you have a simpler rotating system.

A pressure clamp does it's job well, except that the thrust bearing wears and induces vibration into the system. It also couples the chassis or sub chassis to the rotating system at another point.

A clamp applied by the user normally uses some form of mechanical means to apply pressure to clamp the CD. The main problem here is that we humans tend to push down, sometimes driving the table downwards. This throws out the the focal distance and may even allow the CD to contact the pickup housing. That and it's more work!

In the end, I prefer not to trust human fingers and allow mechanics to take over. Much more reliable and easier too. The magnetic clamp would seem to be the way to go as long as it has been designed without major faults. I had to add that.

-Chris
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Old 15th October 2007, 09:41 PM   #10
poynton is offline poynton  United Kingdom
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Anatech.

A good answer.

I actually have an open mind on this but could not see on what the "anti-magnet" brigade were basing their stand.

As for aluminium and plastic being magnetised ..............

Andy
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