This is topic distorted audio output (AKA: Robosound) in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.


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Posted by Peter Angelo Bua-ay (Member # 7564) on 04-27-2013, 10:36 AM:
 
Cinema Set up:
Server - Doremi showvalt IMB
Projector - CP2230
Audio Processor - Dolby CP650

The problem is when it comes to part of the movie/features that has high sound effects, the audio become distorted. And when it become distorted, it will become distorted to till the end and till the last show. Amplifiers are not clipping, audio processor is also working fine (tried also to replace to processor but same problem occurred. Is my assumption that the IMB is the causing problem?

Does anyone already experience this same kind of problem and how does it resolved.

Admin edited subject for clarity on future searches

[ 04-27-2013, 12:48 PM: Message edited by: Brad Miller ]
 
Posted by Carsten Kurz (Member # 5396) on 04-27-2013, 11:15 AM:
 
Search the forum for 'Robosound' - it seems the CP650 causes that problem when using the digital inputs from the IMB. I don't think the Doremi causes that problem.

- Carsten
 
Posted by Brad Miller (Member # 2) on 04-27-2013, 12:47 PM:
 
Ditto to Carsten's comment. Just power cycle the CP650 sound processor the next time it happens and the outstanding odds is it will wake back up and be happy again.

There is no known/proven "fix" for this (other than to use an external D to A converter and go into the CP650 via format 11, which is what we do).
 
Posted by John Thomas (Member # 6509) on 04-27-2013, 06:13 PM:
 
I thought someone said a replacement Cat. 790 could fix this, if you got a "good one." Is this not the case?
 
Posted by Steve Guttag (Member # 268) on 04-27-2013, 06:33 PM:
 
It is clear that some CAT 790s are more prone to this than others...we had a customer that had an issue with a CAT 790 (new) and upon replacing it, the Robosound never returned.

Dolby is working on a software fix to the problem but nothing has been released, to the best of my knowledge. I try to avoid using the CP650 for DCinema except in mixed film/digital systems and even then just let the CP650 handle the film.
 
Posted by Peter Angelo Bua-ay (Member # 7564) on 04-27-2013, 06:42 PM:
 
I've already replaced the CAT790 board and also the whole processor too.

Miller,

If this is a bug on cat790 board, is there a fix available now from dolby?
 
Posted by Manny Knowles (Member # 1171) on 04-29-2013, 09:07 PM:
 
quote: Brad Miller
There is no known/proven "fix" for this
quote: Steve Guttag
Dolby is working on a software fix to the problem but nothing has been released, to the best of my knowledge.

 
Posted by Peter Angelo Bua-ay (Member # 7564) on 04-30-2013, 08:54 PM:
 
meaning additional cost again to cinema exhibitor for additional converter..
 
Posted by Manny Knowles (Member # 1171) on 04-30-2013, 11:10 PM:
 
I think Brad is saying that right now the safest solution seems to be using the analog inputs via a D-A converter.

But, in the future, if Dolby can resolve this, it may be something that can be addressed via software. In which case, one would hope it would be offered as a free software update. (Or firmware, etc)

One would hope...or expect...the fix would be free.

FWIW, I have not experienced Robosound for well over a year now. IIRC it showed up right away and we ended up replacing with a whole new 650 and 790.

(Now, I better go knock on wood.)
 
Posted by Ken Lackner (Member # 1002) on 05-02-2013, 08:35 AM:
 
I've read about this issue on this forum over the last couple of years. I only have 7 CP-650's, not a very large number. To my knowledge, unless the staff are rebooting the processor when the issue occurs and not informing me, that site has not experienced this problem. All 7 use the Cat. 790, no external D/A converters. Is the problem isolated to a certain vintage of Cat. 790? Like, bad componentry prior to a certain serial number? Any theories as to why none of my CP-650's (again, to my knowledge) have experience this issue, while others report it happening frequently?
 
Posted by Steve Guttag (Member # 268) on 05-02-2013, 07:24 PM:
 
I too had zero problems until some DCinema installs in 2012...the problem is...if you have it...it is VERY annoying since it is a show stopper and the CP650 is not the fastest processor to boot up.

I have found that either you have the problem or you don't.
 
Posted by Peter Angelo Bua-ay (Member # 7564) on 05-02-2013, 10:14 PM:
 
Robosound happen/experience only with server processor combination of Doremi IMB and dolby CP650 (based on my observation here, just don't know on other countries). We have the same set up but using different server and we never experienced the problem. Are the manufacturers aware on this?
 
Posted by Steve Guttag (Member # 268) on 05-03-2013, 06:29 AM:
 
Mine have been on Dolby servers.
 
Posted by Scott Christopher (Member # 834) on 05-12-2013, 08:09 AM:
 
I've had the same problem on 2 out of 3 screens here. All use Doremi servers and cp650's with cat.790's. Cinema 1 (which doesn't have the problem) has a rev.5 board - Cinemas 2 & 3 both have rev.4 boards and both have had problems (robosound and a couple of films have had 'popping/cracking' in the surround channel). I've never had to reboot to solve the robosound, just pressing the format button again clears it up.
 
Posted by Steve Guttag (Member # 268) on 05-12-2013, 06:26 PM:
 
Repressing the format button or switching off of the format and back sometimes works. But I would not bank on it.

Since the CP650 clocks ALL channels off of the 1/2 pair...I was wondering if interrupting that line and re-establishing connection wouldn't clear the issue.

-Steve
 
Posted by Jorgen Larsen (Member # 5302) on 05-12-2013, 06:44 PM:
 
This problem is also known in Denmark. We have not yet seen a solution to the problem, but it helps to switch to an analog format (05 or 04) and back again as Steve writes. But you will unfortunately have to "rewind" the movie back a little so the audience can see the sequence again.
I hope that soon there will be a solution to this annoying problem.
Incidentally, it seems that all digital cinemas in the world are facing similar problems.
 
Posted by Marco Giustini (Member # 4544) on 05-13-2013, 01:19 PM:
 
all digital cinemas with CP650 and cat 790! This is not an issue if using any other solutions.
 
Posted by Mohd Ridzuan (Member # 7054) on 05-30-2013, 04:50 AM:
 
Hi All,

Just want to share mine. i've installed many doremi with cp650. some with 790 some without 790 card. without the 790 card i use USL Dax-602 (D-A converter) and with 790 card it's ok for a while likely about 1 month. After that the popping sound happen. i try to install the odyssey card also sometime its happen.

So for now on i just install the USL Dax-602 to prevent any popping sound.

Please advise or suggest if there a better method

Thanx

Mr. Wan
 
Posted by Peter Angelo Bua-ay (Member # 7564) on 05-31-2013, 10:25 PM:
 
Thanks for all your sharing and comments. Since the cinema can't provide DA converter for now, what we did was to disable the surrounds sound (Ls,Rs and back surrounds). We observed that by disabling the surrounds eliminate the popping/robosound but of course with a lesser quality of sound.
 
Posted by System Notices (Member # 2357) on 12-01-2017, 09:39 AM:
 

It has been 1644 days since the last post.


 
Posted by Ken Lackner (Member # 1002) on 12-01-2017, 09:39 AM:
 
I'm back to researching this because I have a site that has had the problem in two different auditoriums recently. I'm not about to disable the surrounds, but I'm quite curious as to how that would prevent this issue from happening. Peter, how exactly did you disable the surrounds, and has it totally prevented the issue from reoccurring, or has the problem returned? (I figure four years would be long enough to determine if the problem is gone!)
 
Posted by Sam D. Chavez (Member # 1841) on 12-01-2017, 10:23 AM:
 
I would assume they turned the amps off. Don't see what useful info you are hoping to learn here. By now they've probably switched to another processor.
 
Posted by Jim Cassedy (Member # 4115) on 12-01-2017, 01:33 PM:
 
I had this problem at one location, and as Sam says, the easiest
way to deal with it was to turn off the surround amps.

- - But not permanently! Since this was an intermittent problem, that
only occurred once every several months, killing the surround amps
was the quickest way to "fix" the affected show until a complete re-
boot could be done before the next scheduled show.

Never had anyone complain about the surrounds being off. I doubt
they even noticed. They were just glad the 'noise' was gone.

Even though this problem only happened once every 3 or 4 months,
the staff kept whining that it was "too much trouble" to go up and
turn off a couple of switches in the booth to kill the surround amps,
or do a re-boot. So the theater eventually replaced the processor.

(But if it were up to me, I would have replaced the staff)
 
Posted by Jack Ondracek (Member # 1466) on 12-01-2017, 03:18 PM:
 
When we converted, we had intermittent problems, which sound something like what's being reported here. Our initial installation was with Doremi's D-A converters. Replacing them with USL's converters fixed the problem (drive-in. We don't use processors here).

It appears our problem was related to electrical noise, getting into the unshielded CAT-5 lines the installer used to run audio to the converters, which USL's appear to be less sensitive to.
 
Posted by Ken Lackner (Member # 1002) on 12-01-2017, 04:05 PM:
 
What I'm hoping to learn here, Sam, is if the site found another temporary remedy other than stopping the show and rebooting the processor. I would not for a second assume that they replaced the processor. There are tons of these out there still running.

Jim, I'm not sure that the problem you describe is the infamous "robosound." I could be wrong, but I thought that was on all channels. Is CP-650 robosound unique to the surround channels?
 
Posted by Sam D. Chavez (Member # 1841) on 12-01-2017, 05:07 PM:
 
Ken,

I guess but there are may more recent robo sound cases than one in Philippines. It can be a maddening issue to sort. I have a couple in my area and yet I've never heard it for myself. Everything I've ever heard about this involves the 790 card and the surround channels.
 
Posted by Stephan Shelley (Member # 8587) on 12-01-2017, 07:48 PM:
 
Dolby has a beta CP650 firmware to get rid of the robosound issue. You can contact them to get it if you need it. One side effect the beta software has is a pop in the sound when switching between digital and analog inputs.
 
Posted by Brad Miller (Member # 2) on 12-01-2017, 10:18 PM:
 
The beta software reduces the issue, but it doesn't fix it completely.
 




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