CRC error nightmare cured by changing power source for FOH!

[digidesigner]

I had an experience, where gazillion clicks and pops, CRC errors and snakes swapping twice a second was finally cured by taking FOH power from the stage.

Turned out FOH power and stage power did not come from the same source and difference between them turned Venue system useless.

Sure enough we found that out only after swapping physical snakes and consoles with no luck

[doug sjostrom]

Was the power coming from generators? In that case, I could see this happening if they were not synced. I saw power fail a few times at the first Outside Lands Festival in SF because of this. If the power is from a utility company I would think the worst that would occur is a possible uncommon ground, but power can be tricky and I'm no expert. Any one else know more?

[digidesigner]

Originally Posted by doug sjostrom

Was the power coming from generators? In that case, I could see this happening if they were not synced. I saw power fail a few times at the first Outside Lands Festival in SF because of this. If the power is from a utility company I would think the worst that would occur is a possible uncommon ground, but power can be tricky and I'm no expert. Any one else know more?

It was a large ice-hall and our tech guy said the power came from different substations in the house. They might be slightly different and somehow out-of-sync.

Still I think Avid team should try to make upcoming systems more resistant to this type of problems.

[Brent Lind]

Did you have a UPS at FOH?

[digidesigner]

Originally Posted by Brent Lind

Did you have a UPS at FOH?

Yes as always, one PSU thru UPS. What this has to do with anything?

[Brent Lind]

If you don't think a UPS is relevant in a discussion of a power related system failure, that's fine. I'm just curious as I've run many systems on seperate sources between stage and FOH without issue and would like to hear more about what caused this. Ground conflict? Voltage differential between the sources? Does your UPS regulate voltage as well?

[Greg C]

Ground loops can and do occur in network data systems. Since it's data and not audio or video, it's difficult to tell if it's occurring. When it does with ethernet networks, the result can be lost packets and corrupt data. Instead of using copper for the interconnects, using glass will eliminate any chance of a ground loop problem. Anytime you're in a live sound setting, you still need to make sure you're using the same sub panel/ground bus when interconnecting FOH, back line, and monitor systems if the interconnects involve any copper where there is a ground interconnect. Ethernet cables, host cards, and switches all have ground connections to the power supply just like audio wiring. The only time you can run loose with having common power distribution is when you use fibre optic interconnect.

[Sheldon Radford]

Yep, Greg pretty much summed it up. Data errors can occur when any two devices are at different potentials; these errors can be avoided by using a common power scheme for the entire audio system.

Sheldon

[digidesigner]

Originally Posted by Brent Lind

If you don't think a UPS is relevant in a discussion of a power related system failure, that's fine. I'm just curious as I've run many systems on seperate sources between stage and FOH without issue and would like to hear more about what caused this. Ground conflict? Voltage differential between the sources? Does your UPS regulate voltage as well?

I'm sorry, I did not want to sound rude. Yes we too never had a similar situation! This thread was put up by me for not so much as for a discussion but for a heads up for anyone in the similar situation. I've seen a couple of CRC's here and there, but when you have constant CRC's and you can see on devices tab that snakes are constantly swapping then you know it's a power source/ground conflict not a problem with the snake.