Re-Connecting Speakers to Sound Processor

[Jake Sinn]

It's not like there's a tape standard or something. He just noticed from your first pictures that the wire connected to the Right channel terminal has a band of tape on it.

As has been stated a few times: once you have ID'd all of the channels you should absolutely label them with masking tape to save you or the next guy the hassle next time.


In that picture I see three amplifiers with two channels apiece, which is a pretty common setup for a 5- or 6-channel system.



When do you think you'll be on site to take a look at this?

So what does the two channel, 3 piece system indicate?

I will be going to take a look today.

Also, in the event that the cables are not labeled, what would be the best way. We have talked about the battery idea, and it was said that that wasn’t a good idea to send power into the amps. And the cables are wired in the wall too, so any other suggestions?

[Carsten Kurz]

Jake, you have no technical background at all, and I don't mean to insult you saying this. It was stupid to not mark the cables when the processor was removed (and I do not even imply you did that yourself).I remember your discussions about open-air setups and so. Heck, is there no one near this theatre with some basic AV knowledge? You shouldn't be urged to perform this type of operations yourself. I mean, it's New Jersey, not the end of the world (oh well...).


The battery trick works between amps and speakers, not between a processor and an amp. Well, there's a chance it would, but it's risky or gives ambiguous results.
You would also need a second person, one in the booth, one in the auditorium. Forget about the battery idea!

You could use a smartphone with a traditional headphone socket as a test signal generator, but you need a special cable or open-wire cable for it. Following the existing cables should still be easier.

You can see the order of the red (+) and black (-) wires. You know that 'Right' can clearly be identified by the piece of tape on one cable (if that still exists). So, connect that cable first. Make sure all the equipment is shut down while you deal with the cables.

Go there and see where the other ends of these cables go to, and wether they or at least the amps are labeled with channel markers. You need to follow each cable towards the amps and see where they go to. Usually, these cables are connected at the back of the amps. Again, switch off the amps, use a torch, and be careful not to activate/shift small switches at the back of these amps, these can sometimes kill your speakers.

Take pictures, and use a flash, or take a lamp with you. Take a sharpie and some tape with you.

Here is a channel ID test DCP. I assume you are able to download it, unZIP and copy it to a USB-Stick, and ingest it onto your DCP server. This is needed to check proper audio channel routing while you're fixing the issue, and most importantly afterwards for a final check.

It plays the subwoofer/LFE as well, but you can just ignore it.

https://www.magentacloud.de/lnk/YiAmHP8D



- Carsten

[Marcel Birgelen]

You can just reconnect the unmarked cables to the positions previously used, play the test DCP a few times and listen how the channels are matched. From there it's easy to deduct what has been connected correctly and wrongly and what needs to be adjusted. Just stand close to the screen so you can clearly hear which channel the sound is coming from. This isn't really rocket science.

[Harold Hallikainen]

I've often checked an amplifier input by just touching the wires with my fingers and listening for hum (60 Hz in the US, 50 Hz in Europe). If there is a person in the auditorium and another in the booth touching wires that can talk to each other (a cell phone call between the two works well), the speakers can be identified by listening for the hum.

Good luck!

Harold

[Carsten Kurz]

It could even work with one person IF the booth monitor allows. But will we learn what type of monitor is installed, and how it is wired?

[Marcel Birgelen]

Yeah, given the situation, I'd say try to get ANY A/V tech in there, even a halfway competent one will have it figured out in a few minutes.

I've often checked an amplifier input by just touching the wires with my fingers and listening for hum (60 Hz in the US, 50 Hz in Europe). If there is a person in the auditorium and another in the booth touching wires that can talk to each other (a cell phone call between the two works well), the speakers can be identified by listening for the hum.

Well, I'd be a bit hesitant to simply touch some unknown wires that "disappear into the wall" with my bare fingers.

[Sean McKinnon]

I will apologize in advance if this comes off as harsh and I mean all of this in the most respectful way possible but there are plenty of competent technicians in the NJ/NY area who probably aren't doing much these days and would be more than happy to pick you up as a client and come down and do this properly. I don't understand why someone would remove a processor unless it was to use elsewhere or there is more to this story than you are telling us. The only way to REALLY do this correctly is to have a real tech come down with proper test equipment and determine which amplifiers go to which speakers. Once this is reconnected the system should AT A MINIMUM be checked for SPL's even if "nothing" changed. Removing and re-installing Cinema Processors from a real movie theatre that presents content to the public is not something that someone who is untrained and does not possess the appropriate test and alignment gear should be doing. You could potentially cause tens of thousands of dollars in damage to your sound system at worst and at best probably be presenting an inferior sound experience to the paying public.

Please don't take this as discouragement but the Dunning-Kruger effect is real. Wikipedia When I was a projectionist I thought I knew everything about projection and sound. Now that I am a Technician/Engineer for many years I realize that even my current knowledge is tiny and that I don't know it all and need to ask for help sometimes. Asking for help is not deficiency and does not mean anyone is less than. When I say asking for help in this context I mean recognizing how over one's head they are and asking for someone qualified to be brought in to complete the task not coming on a forum of professionals and asking for them to tell you how to do something without basic skills or knowledge (for example in signal flow). Take this as motivation to get a real tech and learn everything you can from them. Be a sponge when they are there and watch what they do and ask questions. That is how I (and I assume many others) got started.

[Sam Chavez]

Nice and very insightful comments Sean. We seem to be getting more of these threads where the writer is clearly over their skis and not just on some esoteric issue that has some fun to it. In this case, someone removed (stole?) the cinema processor and now someone else is trying to be e a hero but without any idea wtf they are doing and somewhat belligerent when called on it. We should have some rule on when we give them the boat. In previous years Brad would have done it by now.

[Marcel Birgelen]

You could potentially cause tens of thousands of dollars in damage to your sound system at worst and at best probably be presenting an inferior sound experience to the paying public.

Given the fact that there is apparently no LFE and just a single surround channel, I guess we're already somewhere in that territory.

But yeah, we all agree that a real tech should have a look at it, but looking at how those other topics he started progressed, I have the hunch this is not going to happen.

[Jay Wyatt]

Sean nailed it. The fact that this trivial signal flow exercise is now a 3-4pg thread speaks to why its probably best to just get a professional in there to handle it.

[Tom Ruff]

what city are you in? If you are close I could come show you.