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Author Topic: Do Midas stageboxes need on-line UPS ?  (Read 6412 times)

Mac Kerr

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #10 on: May 31, 2018, 12:22:41 PM »

hey

With UPS there are two thing to consider (as well as appropriate size etc).

The term online refers to the fact that some systems the battery sits idle until a powercut is detected, then the unit switches over to the battery. This can take a few ms, and while a lot of equipment wont notice this some will and get a bit twitchy or have issues. An "online" UPS is one where the battery is always on. The things plugged in always run on the battery, but the battery is constantly being charged by the mains so things stay full, and then if the mains go off, there is no switch over time the plugged in items just continue to run from the battery.


The other thing to look at is double inverted systems and simulated sine wave power.  AC gets fed into the UPS and converted to DC for the battery. To then power the equipment it has to turn back into AC again.  Some systems have a second inverted to convert it back to proper AC, some just use a simulated sine wave in a kind of similar way to audio being represented digitally. Just like audio, higher sample and bit rates lead to a "smoother" representation of the audio, and so some of the simulated sine waves are better quality or more realistic than others. Again some equipment will be fine with either, some a little more sensitive and may have issues depending on how fine a resolution the simulated sine wave is. Some may just not like it at all and want a proper inversion back to AC.

K

Kevin, what has your experience been with simple UPS devices that have a switchover time? In 18 years of using digital consoles I have had more than a few times when power was interrupted, either unintentionally or intentionally, using this type of UPS, and I have never experienced an issue with the protected equipment not continuing to function normally throughout the changeover in both directions.

Mac
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Jeremy Young

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #11 on: May 31, 2018, 04:34:24 PM »

Here's a worthwhile read on the topic at hand. 

My take-away (I am not an electrical engineer and this is not advice) from re-reading that document again is that relatively low-load digital devices with switch-mode-power-supplies under normal conditions shouldn't experience any power failure during the transition between shore power and battery on a line-interactive UPS, due to their inherent ability to "ride through" the zero crossing on alternating frequency power.

Direct quote from linked white paper: "SMPSs are the power supplies found in virtually all mission-critical equipment. They must have a "ridethrough” time of 10 milliseconds or more to comply with international standards (see Figure 3). Any electronic equipment that cannot sustain such a ride-through time is generally considered to be of inferior design or extremely rare — most likely a specialized application (i.e. not computer or IT equipment)."

The paper has a lot more to offer though, so it's worth a complete read.

Mark, do you know what type of power supply your Midas stage box uses?
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Mark Wilkinson

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #12 on: June 01, 2018, 02:53:51 PM »

Here's a worthwhile read on the topic at hand. 

My take-away (I am not an electrical engineer and this is not advice) from re-reading that document again is that relatively low-load digital devices with switch-mode-power-supplies under normal conditions shouldn't experience any power failure during the transition between shore power and battery on a line-interactive UPS, due to their inherent ability to "ride through" the zero crossing on alternating frequency power.

Direct quote from linked white paper: "SMPSs are the power supplies found in virtually all mission-critical equipment. They must have a "ridethrough” time of 10 milliseconds or more to comply with international standards (see Figure 3). Any electronic equipment that cannot sustain such a ride-through time is generally considered to be of inferior design or extremely rare — most likely a specialized application (i.e. not computer or IT equipment)."

The paper has a lot more to offer though, so it's worth a complete read.

Mark, do you know what type of power supply your Midas stage box uses?

Thx guys,

Jeremy, your post/link was spot on for what I was asking about..... 
I guess the standard 10ms "ride through" for SMPSs helps explain why Mac hasn't had any issues over the years.

The Midas stagebox has an auto ranging SMPS, so I've got an interactive UPS on the way...
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Jeremy Young

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #13 on: June 01, 2018, 04:37:32 PM »

Excellent!  Thanks for the follow up.

My iLive(s) are on line-interactive UPS's at both ends (stagebox and surface) at all times.  So far shore power has been reliable and I haven't had a good "test" experience to share yet.  Here's hoping power continues to be perfect for every gig forever and that I haven't just jinxed myself, haha.
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John Penkala

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #14 on: June 01, 2018, 10:40:47 PM »

On power loss, my DL-155 goes off like a rifle crack.
I'm hoping that a good interactive UPS has a fast enough switch-over to stop this.
The quickest interactive I've seen is 4ms.  Is that fast enough?

Time to fix.....thx.

Mark,
         I would hope that a Midas Pro Series stagebox would have output relays that mute the outputs before a spike is passed when power is lost. Is there a chance that an upstream source might be causing a spike? Perhaps something on the same circuit as the stagebox?

JP
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Rob Spence

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #15 on: June 02, 2018, 12:02:16 AM »

Years ago I was the power guy for our local ham radio club for the annual field day. 24hrs of operation off the grid. We operated in class 5A which gave us 7 stations including bonus ones. Stations were 100 watt and included a laptop computer and lights.

We built a zero crossing switch to transfer power from one generator to a backup so we could service the primaries.

Our design didn’t work for the power we needed so we tried UPS . They turned out to be problematic with the contractor type generators. Sigh...

So, we tried a simple double pole double throw contactor (relay). Worked fine. The laptops, of course, didn’t notice since they have batteries. The transceivers also didn’t notice since the power supply had sufficient reserves to handle the short outage.

I would think most electronics would survive the relay transfer in a UPS.


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Mark Wilkinson

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #16 on: June 03, 2018, 11:00:50 AM »

Mark,
         I would hope that a Midas Pro Series stagebox would have output relays that mute the outputs before a spike is passed when power is lost. Is there a chance that an upstream source might be causing a spike? Perhaps something on the same circuit as the stagebox?

JP

Hi JP, I didn't know stageboxes ever had output relays..... I've always thought of them as processors, with electronic mutes only ??

But you've made me think back and question why I feel convinced the DL-155 is the source of the crazy pop, as I do have AES processing inserts running thru the stagebox before its final analog output going to my amps.

Entire chain is X32 AES50 to DL-155, DL-155  AES3 out to processors, processors'  AES3 back to DL-155, DL-155 analog output to amps.

My logic on pinning the DL-155 as culprit rests on this:
When I accidentally forget and turn off the X-32 before tuning off anything else, I get a minor pop.
When I accidentally turn off the DL-155 before turning off anything else, I get the explosive crack....(which I also get on a power loss)

I'm thinking that defines the DL-155 as culprit?    With an idiot accomplice sometimes  ;D
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Dave Garoutte

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #17 on: June 03, 2018, 04:08:10 PM »

I had my Soundcraft 32 stagebox do the giant pop when someone kicked out the plug and replugged it.
That's why I always use a UPS now (and try to idiot proof my power)(see tag line).
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Mac Kerr

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #18 on: June 03, 2018, 06:01:18 PM »

I had my Soundcraft 32 stagebox do the giant pop when someone kicked out the plug and replugged it.
That's why I always use a UPS now (and try to idiot proof my power)(see tag line).

Good plan. As I've said before, I don't think the exact type of UPS is all that important with the electronics we deal with day to day. HERE is an example of the type of UPS I use a lot of. On a medium to large show we might have a half dozen of these that get used as "throw down" gear for anything that we think needs protection from rebooting (remote Rio rack, comms, etc). The FOH rack, or certain racks backstage may have a more robust rack mount unit, but maybe not. The throw downs seem to be just as effective.
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Mark Wilkinson

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Re: Do Midas stageboxes need on-line UPS ?
« Reply #19 on: June 03, 2018, 07:28:00 PM »

Good plan. As I've said before, I don't think the exact type of UPS is all that important with the electronics we deal with day to day. HERE is an example of the type of UPS I use a lot of. On a medium to large show we might have a half dozen of these that get used as "throw down" gear for anything that we think needs protection from rebooting (remote Rio rack, comms, etc). The FOH rack, or certain racks backstage may have a more robust rack mount unit, but maybe not. The throw downs seem to be just as effective.

Thx Mac, your UPS example looks very practical and affordable. Nice to know it has worked well.
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ProSoundWeb Community

Re: Do Midas stageboxes need on-line UPS ?
« Reply #19 on: June 03, 2018, 07:28:00 PM »


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