[sdiy] UPS to protect gear....worth it?

[Tom Arnold]

On Fri, Mar 24, 2006 at 09:02:36AM +1100, Brett Maddaford wrote:
>    Does anyone here use a UPS to filter their power supply and do you
>    think its really worth it?

I'd recommend against using a standard computer UPS on audio gear.  The
power is usually squarewave or stepped sine wave output which the power
supplies dont care for too much.  Computer supplies and other switchers dont
mind and they are much cheaper then true sine UPSes so thats why they are
everywhere.

I used a UPS on my gear back when I had the room for a proper one that used
a *HUGE* transformer and was true sinewave.  You can find these around, they
are usually about the size of a washing machine and with the batteries
removed still weigh about 500lbs for a 5kva unit.  The primary of the 
transformer goes to line-in, one secondary goes to line out, and there is a 
second secondary that goes to the UPS circuitry.  

If power droops, the 2nd secondary is used to inject power into the core.  If 
primary fails, the UPS injects power into the core to fully cover it.  
The uninteruptable part isnt the switching time, its the time it takes the 
field to collapse in the transformer which is why its so bloody heavy.
These things can be aquired for free if you hang around the right places.
Bean counters see 5kva and 2 cubic yards and the math fails them
completely...

Anyhow, most sane people dont have room for that...  what you should have
room for tho is a proper line conditioner.  Should also weigh 100lbs or so
and is just a large inductor usually with multiple taps on the primary so it
can compensate for large power flucuations.  I've normally found SOLA units
fairly cheap and I consider them very usefull.

-- 
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 - Tom Arnold       -  Free Synth DIY webspace http://www.sdiy.org 
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