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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » DMA8Plus Sound popping issues (Page 1)

 
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Author Topic: DMA8Plus Sound popping issues
Peter Clay
Film Handler

Posts: 16
From: Alderney, Channel Islands
Registered: Aug 2013


 - posted 08-30-2013 06:48 AM      Profile for Peter Clay   Email Peter Clay   Send New Private Message       Edit/Delete Post 
Hi,

I volunteer as a projectionist for a tiny little one screen cinema in Alderney in the Channel Islands. We have just made the move to Digital and we are having issues with sound dropping out during screenings. I'm pretty sure I know what the problem is it's just trying to get the other volunteers to agree and what the best action to take, so here is all the information of what actually happens.

Whilst the film is playing every now and then we will get sound pops and clicks or even the sound dropping out all together but only for a second or 2 then it comes back on (it did happen the other day for just over 3 secs which was quite worrying). it Also happens when the auditorium lights are switched on or off, and also when the lights are turned on or off in the projection box.

Now the problem here in Alderney is the electricity supply on the island is pretty shoddy and it can range anywhere from 210 volts up to as high as 270 volts and it's not steady. I have noticed when you turn the lights on or off the lights on the DMA8Plus processor go out for a second which is why the sound goes and I believe that when the sound pops during a performance there must be a power surge or something as the lighting circuit is the same circuit as the plug sockets which is what I believe is causing the problem.

I have tried explaining this that we need a separate circuit for the lighting or the plugs but it's difficult here to get someone to sign off on it as it is a volunteer run cinema with trustees and we then need to get the landlords permission to start changing the electrics etc.

what they want to do is get a UPS system which I think would be a good idea anyway to protect the projector from these power surges but nobody can decide on what type to get and that is why I'm posting here to see if anyone here has any ideas on what type of UPS to get, as someone already went and brought a surge protector but all that does is switch the power off completely when it detects a surge which is no good in the middle of a performance as the projector will just switch off.

Thank you for taking the time to read this and I hope it makes sense and isn't to much rambling

Peter Clay

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Carsten Kurz
Film God

Posts: 3680
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 08-30-2013 07:21 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
What type of projector and server do you have?

Seems a UPS would be a good idea. One would have to think about the proper type/technology and UPS settings to get away with these conditions. I know that the APC SmartUPS have these settings, e.g. configurable thresholds.

You should get a qualified electrician in and let him analyse the situation and wether more/new lines would improve the situation.

- Carsten

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Tony Bandiera Jr
Film God

Posts: 2942
From: Moreland Idaho
Registered: Apr 2004


 - posted 08-30-2013 12:30 PM      Profile for Tony Bandiera Jr   Email Tony Bandiera Jr   Send New Private Message       Edit/Delete Post 
Carsten is correct but I must "disagree" with him on two key points:

1: Avoid APC UPS!! They have gone WAY down in both quality and reliability since they were bought out by Schneider Electric. I suggest Tripp-Lite or Middle Atlantic instead. Both have proven very reliable over the long term. (And a 1500va or 2200va size is more than adequate to protect the projector's electronics [for those projectors like NEC or Christie that allow a separate UPS connection] and your DMA8plus.) You would select the "240volt" models.

2: A separate or additional circuits installed will NOT do anything to eliminate the problem. If the incoming power is bad, more circuits will NOT "clean it up." That said, it still would be good for an electrician to look at the circuit situation and get the lighting off of the plugs circuit.

Your ONLY real solution is to put the projector electronics, DMA8plus AND cinema sound processor on the UPS.

Do it soon as the power variations you described are very bad for the equipment.

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Peter Clay
Film Handler

Posts: 16
From: Alderney, Channel Islands
Registered: Aug 2013


 - posted 08-31-2013 01:34 AM      Profile for Peter Clay   Email Peter Clay   Send New Private Message       Edit/Delete Post 
HI guys

Thanks for the advice. I'm showing Monsters U tonight so I will get all the model numbers of the projector and sound processors etc to see what type of UPS rating would be big enough to power them.

I'm trying to convince the others here that we need to get an electrician in as I know a couple over here who do a service where they fit something to the incoming distribution power board that helps to regulate the power, like I said the power on this island is pretty shoddy (very small island, only 3 miles by 1 mile with an oil/diesel powered power station and only about 1500 residents).

again thanks for the advice

Pete

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Marco Giustini
Film God

Posts: 2536
From: Reading, UK
Registered: Nov 2007


 - posted 08-31-2013 05:17 AM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
Maybe you should consider an "online" UPS which will not just filter but recreate a full sinewave out of the mains. If you have frequent spikes and drops sounds like a necessity to me. Digital Cinema parts are expensive, the price of a good UPS will repay itself over time

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Louis Bornwasser
Film God

Posts: 4426
From: prospect ky usa
Registered: Mar 2005


 - posted 08-31-2013 06:52 AM      Profile for Louis Bornwasser   Author's Homepage   Email Louis Bornwasser   Send New Private Message       Edit/Delete Post 
IREM (the same guys who made the 35mm rectifiers) are also in the business of power regulation. Small and large are available. I saw a regulator for an African hospital at the factory that was a 240v 3 phase model for 1000 amps. Louis

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Peter Clay
Film Handler

Posts: 16
From: Alderney, Channel Islands
Registered: Aug 2013


 - posted 08-31-2013 11:49 AM      Profile for Peter Clay   Email Peter Clay   Send New Private Message       Edit/Delete Post 
Hi,

OK I'm at the cinema now and here is the equipment we have.

NEC NC900C-A
DMA8PLUS
CP65 sound processor
QD 4960 Quad Amplifier

the dma8plus cp65 and quad amplifier are in a couple of double plug sockets and the projector is wired direct to its own rocker switch but I couldn't say if that's a different circuit or not.

as I said before when you turn the light switch on in the projection box I notice the (pcm) and (discrete) lights on the dma8plus go out for a second which is when the sound drops, but it also happens sometimes during a performance when nobody has turned any of the lights on or off making me think that must be when we get the power spikes.

thanks for your time

Peter

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Gordon McLeod
Film God

Posts: 9442
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 08-31-2013 12:19 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
Putting a TVSS on the mains would also be a good idea

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Marco Giustini
Film God

Posts: 2536
From: Reading, UK
Registered: Nov 2007


 - posted 08-31-2013 04:11 PM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
Do you have an IMS in the NC900? How's the sound connected to the DMA8plus?

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Peter Clay
Film Handler

Posts: 16
From: Alderney, Channel Islands
Registered: Aug 2013


 - posted 09-01-2013 03:03 AM      Profile for Peter Clay   Email Peter Clay   Send New Private Message       Edit/Delete Post 
When you say IMS do you mean the actual sever that holds the films etc. if so then yes. From what I can tell the DMA8PLUS is connected by what looks like an Ethernet cable coming from a port on the projector that says AES above it to an adapter like cable which goes into the DMA8PLUS.

Here is a link with the info of the projector with images of the connections

http://www.nec-display-solutions.com/p/uk/en/products/details/gallery/dp/Products/DCP/Current/DCPDLP-NC900C/DCPDLP-NC900C.xhtml?cat=DCP&realm=products%2Fchoice

Thanks
Peter

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Marco Giustini
Film God

Posts: 2536
From: Reading, UK
Registered: Nov 2007


 - posted 09-01-2013 03:53 AM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
I have seen issues with Doremi IMB/IMS (the manufacturer of your Integrated Media Server - IMS) when using ethernet cables for sound. Exactly as you describe. The solution was to use a very short ethernet cable - say 0.5m - and then use an adaptor to a proper AES cable to the DMA8plus.
An UPS is always a good idea, but I would not ignore this point. You can ask your installer to send you a cable and do a quick test just laying the cable on the floor.

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Carsten Kurz
Film God

Posts: 3680
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 09-01-2013 06:24 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Well, the NC900 will allow you to operate the whole projection chain through a UPS. Amps would be the only exception. Normally, projectors/lamp houses are not operated through UPS because they need too much power, but the NC900 allows it. You would probably need a UPS in the 2kVA range, which is not too expensive, but will in the long run save your projector.

I am a bit familiar with supply conditions like this in rural areas of Ireland, my brother-in-law works as an electrician there and he repairs and replaces a lot of domestic gear after voltage drops and spikes.

Don't wait too long.

- Carsten

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Peter Clay
Film Handler

Posts: 16
From: Alderney, Channel Islands
Registered: Aug 2013


 - posted 09-01-2013 07:37 AM      Profile for Peter Clay   Email Peter Clay   Send New Private Message       Edit/Delete Post 
quote: Marco Giustini
I have seen issues with Doremi IMB/IMS (the manufacturer of your Integrated Media Server - IMS) when using ethernet cables for sound. Exactly as you describe. The solution was to use a very short ethernet cable - say 0.5m - and then use an adaptor to a proper AES cable to the DMA8plus.
An UPS is always a good idea, but I would not ignore this point. You can ask your installer to send you a cable and do a quick test just laying the cable on the floor.

Looking at what we have the Ethernet cable is about 2 meters long which then goes into the adapter you describe so should I just get a shorter Ethernet cable and move the DMA8PLUS a bit closer and try that?

quote: Carsten Kurz
Well, the NC900 will allow you to operate the whole projection chain through a UPS. Amps would be the only exception. Normally, projectors/lamp houses are not operated through UPS because they need too much power, but the NC900 allows it. You would probably need a UPS in the 2kVA range, which is not too expensive, but will in the long run save your projector.

I am a bit familiar with supply conditions like this in rural areas of Ireland, my brother-in-law works as an electrician there and he repairs and replaces a lot of domestic gear after voltage drops and spikes.

Don't wait too long.

- Carsten

The guy who installed the projector has sent us a link for some UPS that should be upto the job they're about 2200VA but he said we would only put the projector on it as the DMA8PLUS and amps etc would be to much for it and we would get a seperate surge protector for them, does that sound about right? We've got an electrician coming next week so hopefully we will get everything sorted soon.

Thanks for all your help.

Peter

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Carsten Kurz
Film God

Posts: 3680
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 09-01-2013 09:24 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
DMA8 does not consume much. CP65 the same. These should be powered from the UPS as well as the NEC.Not the amps, though.

The NEC is rated around 1kVA, DMA8 + CP65 may add another 10%, so 2000kVA is completely sufficient. You shouldn't buy the first UPS you come across, though, there are differences and some models may cope better with your conditions than others. It should at least be line-interactive, not a simple switching UPS.

I would think that other businesses in your area will have UPS like this in operation as they are potentially suffering from the same line conditions - maybe you can ask around for experiences with specific models and sources?

- Carsten

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Marco Giustini
Film God

Posts: 2536
From: Reading, UK
Registered: Nov 2007


 - posted 09-01-2013 11:28 AM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
Well, 2 metres is not a massive lenght. What I know is that when using 5-10m long ethernet cables as AES cables, the Doremi give trouble. Cannot say for sure whether 2m is enough to give you trouble or not.

If you go for a UPS, listen to Carsten, do not buy the first UPS on the shelf, at least line interactive, but if your budget allows it, I'd go for an online model.

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