CraigGarnett Contributor - Level 2 2018-12-18

2018-12-18

Does anyone use a ups at foh?

Just curious if anyone uses a small ups for the desk and ancillaries?
The thought crossed my mind when I had to use a long extension lead to get power at a recent show?

Craig

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Re: Does anyone use a ups at foh?

Craig Garnett;157374 wrote:
I'm just thinking about the situation where someone knocks an extension lead out and how long it would take to notice and then how long I'd have to sort it out whilst still running the show!

The Tripp Lite model will beep (and continue to beep every minute or so) until power is restored. So you will know when you lose power.
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Re: Does anyone use a ups at foh?

If it's a gig where I'm playing and running sound from stage, I keep my IEM transmitter plugged into the UPS, but in a surge protected only outlet, not a UPS outlet. That way if the power goes out, I know right away something's wrong 'cuz I lose my IEM's. If I'm just running sound (typically I use an iPad), I keep the router plugged into the UPS but in a surge protected only outlet. Same theory...If the power goes down, I know right away because I lose connection to the router.
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Re: Does anyone use a ups at foh?

That's a good idea Gary, I usually have Mixing Station Pro displaying a rta so that would let me know if the router went off.

Craig
Craig Garnett
Contributor - Level 2

Re: Does anyone use a ups at foh?

I guess I have kind of a hybrid setup:

- Stage Power -> UPS
- UPS Surge Only -> Amps
- UPS Battery -> XR18, Router, Pi

The Pi actually has its own battery backup and auto-shutdown that is triggered by both the XR18 and the router going out at the same time, but that doesn't happen until the main UPS goes down. I also added a relay to disconnect the Pi's dedicated backup battery to prevent any further discharge after it's done shutting down.
(The entire system on stage is in one small rack, so I think I can expect it to not get unplugged from itself.)

So that enforces the proper shutdown sequence - amps off first, allow to stabilize, then everything else - plus a proper automatic shutdown of the Pi. Startup, not so much; it all comes on at once unless someone explicitly turns the amps off while the power is out.


[/HR]
FOH has another Pi running the control app and an IP passthrough for an X-Touch. It has another copy of the same backup that the stage Pi does, but it only covers the Pi itself. So the monitor and the Touch go down immediately, then the Pi sees that and shuts itself down, but it's still a controlled shutdown instead of just "off".

It would be nice to keep the screen on at least, so I can mute stuff or get to a sensible power-on state, but then I'd need an AC-output UPS to run the screen, and those are typically a bit bigger than what I have space for. Oh well, the router is still up at that point, and I have a phone app. Smiley Wink
Contributor - Level 2

Re: Does anyone use a ups at foh?

I've also thought for years about making a battery-powered portable PA for outdoor guerrilla-style concerts. 2x 50-lb bricks of NiMH (airlines don't like lithium) that connect in series to produce 3kWh at 85-0-85VDC. (170VDC with a center tap)

The amps would have to take that DC power directly, so probably DIY all around.
(maybe this? https://www.diyaudio.com/forums/class-d/224052-systemd_2kw-design-33.html#post3414067 )

The rack would run from a bridged amp running a full-scale 60Hz sine. (170Vpeak = 120Vrms)

Probably won't happen for at least a few more years, if ever, but it's still interesting to think about.
Contributor - Level 2

Re: Does anyone use a ups at foh?

ABSOLUTELY!!!! I would NEVER use a digital console without a UPS!! I’ve been burned twice a few years ago and that caused me to listen to people who had been telling to do so. But I didn’t listen. Until...... Two different shows within a week of each other had the power dip suddenly and slightly and enough to cause my X32 to do a reboot. Right in the middle of a song! So fricken embarrassing. The dip was caused by the sudden power drain of my amp rack when a loud and heavy kick drum hit happened. Oh, and before you say it - My amps were on a totally separate circuit on my distro box that was hard wired into 220 and it still did it. I did find a temporary fix until my UPS arrived was to make sure that my X32 was on opposite leg of the 220 from the amps, with the UPS, there’s never a problem. Another “oh, btw” is the a power conditioner doesn’t work. It has to be a UPS because only a UPS can prevent that big of a power drop from happening.
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Re: Does anyone use a ups at foh?

Jeff Bernhardt;157578 wrote:
Another “oh, btw” is the a power conditioner doesn’t work. It has to be a UPS because only a UPS can prevent that big of a power drop from happening.


Yeah, I'm not surprised that a power conditioner doesn't work. I've never seen a difference myself, and considering how a power supply typically works, both linear and switching, I can't see how there could be. Yes, there's a lowpass filter in there, but like this paper says (below), the cutoff frequency has to be above audible for its size and the fact that it's passive. So it can't even keep a buzz out.

https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf?fbclid=...
Contributor - Level 2

UPS at FOH

Craig Garnett;157112 wrote:
Just curious if anyone uses a small ups for the desk and ancillaries?
The thought crossed my mind when I had to use a long extension lead to get power at a recent show?

Craig


I use two cyberlink rack mountable UPS's, one at .FOH, and the second at stage rack/ monitor world. Extremely helpful, when building has flakey power, or a abundance of idiots pulling cords randomly in order to plug in their phone chargers.
Contributor - Level 3

Re: Does anyone use a ups at foh?

A contrarian viewpoint is that a UPS is an additional point of failure. I was at a show where the UPS on the digital snake went down.

In these days of switching power supplies, they are only needed if you are on sketchy power.
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Contributor - Level 2

Re: Does anyone use a ups at foh?

Dan Richardson;159377 wrote:
A contrarian viewpoint is that a UPS is an additional point of failure. I was at a show where the UPS on the digital snake went down.


Hmm...I've never had one fail, except for overload or dead battery, but of course that doesn't mean that they can't. But now that we're talking about the possibility of failure, we really need to look at HOW they can fail. And with multiple ways that they can work, you can't just lump them into one category.

Most of the smaller ones can afford to switch between direct mains and inverter because the switch (relay) required to handle the rated load is small enough to be practical. The default state, then, is passing the mains through so that the load has power, even if it's no longer backed up. (of course, there are other failure modes as well)

Once you get to a certain size, you can't just switch things around like that. So these typically run on battery all the time (no switch), and simultaneously charge the battery while the mains are up. If something goes wrong here, the load is dead.

And of course, there are more variations than just those two, but you get the idea. What design of UPS was it that failed?

Dan Richardson;159377 wrote:
In these days of switching power supplies, they are only needed if you are on sketchy power.


...except you may not know that it's sketchy until it goes out. It was solid during load-in, line-check, tuning, and all that, and then dropped mid-show!

Maybe an idiot architect/electrician decided to put the microphone at eye level for the SPL enforcement (that's where everything goes, right?), and then an idiot drunk thought it'd be fun to yell into it?
Or a squirrel found a transformer? (that happened to my dorm when I was in college)
Or...well, you get the idea.