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Date:      Thu, 17 Oct 2013 14:29:10 +0800
From:      Erich Dollansky <>
To:        Ralf Mardorf <>
Subject:   Re: UPS buying suggestion
Message-ID:  <>
In-Reply-To: <1381988697.5852.16.camel@archlinux>
References:  <> <> <> <> <> <> <1381988697.5852.16.camel@archlinux>

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On Thu, 17 Oct 2013 07:44:57 +0200
Ralf Mardorf <> wrote:

> On Wed, 2013-10-16 at 23:23 -0600, Warren Block wrote:
> > Computer power supplies are not as sensitive as they once were, and
> > the switchover time of standby UPSs is almost certainly adequate.
> I don't own an UPS. Sometimes we've got blackouts here, long enough to
> effect a CRT monitor, but not always the computer is effected too. I
> wonder if it's possible to switch power off and on manually, very fast
> at a power board, without turning off the computer. I don't want to
> test it, but it could be possible.

good power supplies are able to provide electricity on its output for
at least one halve cycle under full load. This gives you at least 10ms.
> > Amusingly, the Smart-UPS provides a cleaner sine wave than comes out
> > of the wall.
> Filters?! I didn't read the link. Mains are polluted by lots of crap,
> e.g. by all the switching power supplies ;). I should mention that I

Industry is much worse. Their machines made early computers fail when
the bigger machines started work.

> was an audio and video engineer a long long time ago. IMO the quality
> of the power from the mains is much more important for audio and
> video, than for computer and even for audio and video it's
> significance often seems to be overrated. Likely that the capacitors
> in the power supplies of my home studio, that are much older than 20
> years, are dried out, but I never repaired an old power supply,
> because there are no audible effects.

Audio is a problem on a Back UPS. Even water pumps complain at lot. The
better the sine wave is, the less noise you get.

I believe you equipment has anlog power supplies which filter the noise
from the power line much better.

> Sure, the quality of the power should be good, but IMO it sometimes is
> overrated, just to have another value that can be used for
> advertisings.

Of course, but will the client pay for it?


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