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Author Topic: uninterruptible power supplies  (Read 2421 times)

springman

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uninterruptible power supplies
« on: May 10, 2004, 12:11:31 am »

After a recent brown-out screwed up a mix I was working on, I vowed to investigate uninteruptible power supplies.  Anyone out there using them?  What gear are you protecting?  How have they performed?  Any recommendations on makes/models?   Thanks!

Eric Kilburn
Wellspring Sound
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Kirk_Candlish

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Re: uninterruptible power supplies
« Reply #1 on: May 10, 2004, 06:10:58 am »

I wouldn't be without them. I have one on the primary computer and another one for rack gear. The key with a brownout is AVR, automatic voltage regulation, it uses the batteries, and is some cases a cap, in the UPS to provide short term correction when the line voltage drops.

I'm using APC Smart-UPS, because they produce a true sine-wave.

You'll find all sorts of brands and deals, you get what you pay for. The cheaper ones create some really nasty looking stepped waves and your gear won't like it.
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Jim Dugger

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Re: uninterruptible power supplies
« Reply #2 on: May 10, 2004, 08:12:34 am »


I bought a true, on-line model from TrippLite.  An on-line or in-line model completely reconstructs the power from DC regardless of the state of the incoming AC.  This is what you want for your audio gear.  I run everthing but the lights and computers from one unit which is rated for 2400 watts.  (about $1200)  You will have to get a 30A socket installed, though.

I have a second, line-interactive (as above) for my computers.

Blips, clicks, etc when the AC kicks on are gone.  I'd also say the noise of the overall system is lower.  
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clicktrack

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Re: uninterruptible power supplies
« Reply #3 on: May 10, 2004, 04:47:56 pm »

They are a must.  

I run a mobile rig and use a APC Back-UPS for the same reason as posted previously.  Being mobile, I never know what the power will be like, so the UPS becomes invaluable.  

My mobile rig runs on one UPS (recorders, console, pres).  It makes my FURMAN conditioner a bit redundant, but I still keep the Furman in the rig for historical comfort-food type of support.  Back in the shop, I use a second UPS for the DAW and a third for the Office PC.  

I became a firm believer in UPSs for all electronic gear because the place I used to live had frequent brown outs.  After the third installation of CPU, memory and HDD, I decided to look at my power situation and noted how much my gear was susceptible to brown outs.  

If you know details of microelectronics, you may realize that brownouts can be potentially more fatal than full outages.  The ICs within a current piece of gear expect to see certain potentials between their pins.  Brown outs cause unknown states within these ICs, which can damage them in full or in part...leading to a situation where the unit, as a whole, is still operating, but internally, components are in failure states or pseudo-failure states...

Run, get a UPS. Your gear will thank you.
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David R.

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Re: uninterruptible power supplies
« Reply #4 on: May 14, 2004, 12:37:19 pm »

Bought one two years ago, when Texas started playing shell games with California's power grid.  

The best feeling in the world is when the circuit trips(I told you not to run the microwave and toaster at the same time), and all goes dark except the important gear that is plugged into the UPS!

I've since moved and had the electrical upgraded on the new place, but keep the studio on the UPS.  

I'm using the APC 1400 pro, and can say nothing negative about it (except the weight!).
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-David R.

Bill Park

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Re: uninterruptible power supplies
« Reply #5 on: May 15, 2004, 08:27:03 pm »

I'd be careful in picking a UPS.  The ones for compters are not designed for reactive loads like those that happen when an amp suddenly needs full power to reproduce a transient, and everything else on the circuit is also demanding a lot of juice.  You could end up starving the gear and degrading the sound.  Make sure that there is plenty of headroom in your setup.

 Bill
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hollywood_steve

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Re: uninterruptible power supplies
« Reply #6 on: May 17, 2004, 08:18:15 pm »

Can a few of you Mr. Wizard types weigh in on the benefits versus cost for an "online" UPS compared to the less expensive "Line Interactive" models?  For someone who is primarily concerned with protecting a single hard disc recorder while on location, is the 2 or 3 times cost difference justified or not?

Thanks.
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Jim Dugger

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Re: uninterruptible power supplies
« Reply #7 on: May 17, 2004, 08:30:36 pm »

It's simple.

A line-interactive model will only help you when the power goes nuts, goes out or gets really ugly.  Provided the power company gets within about 20% of 120v, 60hz, your line interactive model will gladly pass all noise, junk, fluctuations, etc. through to your gear.  It may or may not actually provide true sine wave output when on-line.

An on-line model is "always running off the batteries".  Source AC, good or bad, is used to charge the batteries, and the system reconstructs clean, dependable power from DC.  AC noise, burps, bumps and whatever else are eliminated entirely and there are absolutely no concerns about reacation/switch time.

Line-Interactive models are an excellent choice for computers and generally anything that will communicate with purely digital IO not suseptable to AC noise.  

If it's got analog IO of any kind, I'd put it on an on-line unit.

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Bill Park

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Re: uninterruptible power supplies
« Reply #8 on: May 17, 2004, 09:01:15 pm »

As Jim says, if you have to run a UPS, get one that uses the batteries to feed the equipment.

 Bill
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Barish

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Re: uninterruptible power supplies
« Reply #9 on: June 12, 2004, 12:48:41 pm »

The MD of APC Turkey is my classmate, in fact my seatmate from my high school days (I'm talking about some 17-18 years ago, for those who don't know me) and according to him, for audio/video recording suites a true on-line UPS system is a must, and he reckons this not because he wants to sell more units but because he is aware what surges and brownouts can do to digital equipment and the audio equipment performance and the operational differences between on-line and other UPS systems, the closest cheaper option being line-interactive ones. He says they have dealt with and given consultancy to many recording facilities and had a chance to do a lot of case studies about this. Even though there are Line-interactive ones out in the market that offer a pure sine output like true online types, these LI ones have a response time of 2 to 4 milliseconds, and even that tiny cut-off can be quite critical in audio recordings so he says for a total peace of mind the recordists should go full monty. When he explained their findings to me with diagrams, statistics and samples a few years ago when we hooked up, I was astounded. If one has some electronics background they can see what's going on there and then, not to mention that when you actually hear the difference that's when you are a believer.

I can't imagine a recording environment without one of them now.
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M Ozturk

digiengineer

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Re: uninterruptible power supplies
« Reply #10 on: June 12, 2004, 03:17:27 pm »

I've been using Tripp-Lite UPS's for a few years without complaint; unfortunately, I have had some practical experience with them due to black-outs during summertime in L.A.Sad

One thing I've noticed is that people who run a UPS on their DAW tend to forget something very important: if you run an active extension system for your monitor and USB (i.e. Gefen or something similar), you need a desktop UPS as well. Having a UPS on the CPU side doesn't do any good if you can't save and shut down from the Monitor/Keyboard side.
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Jim Dugger

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Re: uninterruptible power supplies
« Reply #11 on: June 12, 2004, 05:09:19 pm »


I'd like to follow up on my post since there's been a recent development you might find interesting.

I ended up getting a TrippLite system big enough to power my whole studio instead of just the computers.

The model number was a SU3000XL.  I should have paid really close attention to this:  If you remove the capacity rating, the model number becomes "SUXL" which is short for 'SUX Lots'.

Just about everything I hooked up to this thing BUZZED.  Not in the audio, but acoustically.  Several of my microphone preamps were the worst offenders, but so was my control room power amp.  So it would seem, everything with a toriod power transformer would "sing" when running off the tripp-lite, but be perfectly silent when on commercial power.  Nice eh?

They sent me a second unit -- same problem.  They won't let their support techs talk to the engineers, such a shame, so I was unable to further diagnose the problem directly with Tripp Lite.  I worked with both Eric and Dave at tripp lite who were very helpful and kind, but in the end could not solve the problem.

One of my preamp manufacturers I had the trouble with agreed to receieve a Tripp Lite unit and do all the work to diagnose what was going on  -- mind you this is waaay beyond the call of duty.  Tripp Lite set up the demo, and then called the preamp manufacturer back (a manager, I assume, named 'Michelle') to say "we are not in the business of shipping units out to solve someone else's problem!"  What?!  You mean the fact that three different preamps ranging in price from $2,200 to $4,000 and a $1,200 control room power amplifier humms constantly because the output of your so-called pure sine wave UPS is so far from clean you don't consider this your problem?

I don't care what a UPS manufacturer says, when gear runs better off commercial power than the double-conversion UPS that claims pure sine wave output, that's a problem!

Funny enough, the preamp manufacturer (a smaller boutique firm of well respected gear) simply said "You shouldn't worry about it.  Our power supply completely reconstructs the power within the unit anyway.  We ship to Japan and don't make  single change even though they run at 100v and it's 120 in the US.  We designed filtering out commercial power into the unit -- it's unlikely you would have seen any performance improvement running on "perfect" power vs. commercial anyway."

Man, that's why I spent good money on good gear!

They then added Tripp Lite to a "Do Not Use With" list.

At least Tripp Lite call-tagged the "replacement" unit.  I was pretty pissed when I found out they expected me to pay the $90 it costs to ship one of these heavy beasts myself.  In the spirit of honest disclosure, they finally did agree to pay for the return shipping.  The other one was returned to the place I bought it.  So, all I ended up out was some time and the $400 I paid an electrician to install a now not-used dedicated 30A circuit.
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