[Cube] Vibration Isolation

[Steven Southerden Dive]

Seems to me you should worry more about the effect on a CRT display, 
rather than any magnetic media (e.g. the HD). A steady-state magnet, 
such as in a loudspeaker, will not have much permanent effect on nearby 
magnetic materials. But CRT screens are very sensitive to stray fields, 
as precise allignment of the electrom beams is needed for good colour 
rendition. The Sony tubes in many Apple displays have automatic 
de-gausing to prevent build-up of odd colour patches due to these 
fields, but you need to re-start the display from time to time to make 
this feature work. It accounts for the loud thump you hear when 
starting some of these displays, as the de-gausing coils receive a 
short and large current 'kick' that makes the whole unit shake. I use 
an Apple Studio Display 17" CRT (ADC) that came with my Cube, and it 
behaves this way, and it's right next to the Cube. My old 5500 also 
sends out one hell of a pulse, and that's never had any effect, either, 
and that's built into the same case as it's HD.

A high enough frequency alternating magnetic field can wipe, or at 
least wreck, stored data bits. It's all to do with things like field 
strength, coercivity, field flux, magnetic domains, etc. Modern HD's 
use some interesing high order physics to record and read data. There 
will be someone out there with sound knowledge of the physics who can 
give a better idea of the relative risks, though maybe not on this list 
(and certainly not me).

Steve

On 3 Feb 2005, at 19:47, retrophisch at mac.com wrote:

> On 2/2/05 at 10:39 PM, Allan Hise <allan at hise.org> did send into the 
> ether:
>
>> On Wed, 2 Feb 2005, Brett Pearce wrote:
>>
>>> I thought all modern speakers were shielded to allow them to be used
>>> next to TV's?
>>
>> Maybe, but do you want to trust your valuable data to "I thought 
>> that...."
>> I don't.
>
> And define "modern," Brett. The 8-year-old subwoofer sitting in the 
> rack under
> my 36-inch Sony flatscreen isn't shielded, and it was casting a nasty, 
> dark blur
> on the bottom corner of the Sony's tube until I wrapped the sub in 
> copper.
>
> Now granted, I haven't yet had a problem with my Cube sitting on my 
> desk with
> one of the Aiwa shelf stereo speakers right next to it, but we're also 
> talking
> about a much smaller magnet in those speakers. And the Aiwa set is 
> newer than
> the sub+speaker set mentioned above.
>
> chris
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