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[filmscanners] Re: Power Line Filter

On Fri, 29 Mar 2002 21:39:57 EST   (HMSDOC@aol.com) wrote:

> I have a Canon FS4000 and have noticed some noise, nothing terrible but
> sometimes a bit more than others.....then I saw this interesting post:
> http://www.normankoren.com/Tutorials/canoscan4000bbd/messages/96.html

Hmmm. "(my dedicated hi-fi spur is ideal- but very inconvenient)" betrays a
certain pre-existing neurosis... which may lead inexorably to $1000/metre
silver plated OFC copper SCSI leads with PTFE dielectric, handmade by
Tibetan monks, and scanners with spikes on $450 magic tables ;-)

I'm neither convinced nor unconvinced personally. I've tried various
scanners on UPS and separate mains outlets and never seen a noticeable
difference. However there were many reports that poor shielding was part of
the problem with HP Photosmarts, which were notorious for noise modulation
effects. I think the 'modulation' bit gives that credence - any patterning
in what should be random noise suggests interaction somewhere.

I've some sympathy with what he says about vibration. Mechanical resonance
was an issue in the LS30, albeit self-induced rather than external. But it
produced visible effects (the 'jaggies'); if there aren't visible effects,
it hardly matters.

I'd suspect the scanner's own PSU would usually be the bigger problem,
as it seemed to be in the HP's, rather than mains-borne or RFI.

It might be worth putting a ferrite choke on the mains lead, though I
haven't tried that (helps with my hi-fi CD player tho':). But noise is
fundamentally a characteristic of the CCD which needs to be dealt with at
source before we start worrying about small, second-order effects.

I'm still rather suprised that Peltier cooling hasn't made it into
filmscanners, as it's a cheap, proven technology. Adding one would cost a
lot less than a mains conditioner, or even a dedicated spur, and probably
give much more benefit.


Tony Sleep
http://www.halftone.co.uk - Online portfolio & exhibit; + film scanner info
& comparisons

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