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Author
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Topic: Reminder: Don't throw CP650's away
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Robbie Hidalgo
Film Handler
Posts: 47
From: Los Angeles, CA USA
Registered: Dec 2003
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posted 05-02-2005 01:36 AM
Alan,
Well, Brad and Frau Schaffer have definitely nailed all the key points already.
Who's tech-ing Prescott these days, is it Andy? Either way, the pop will only take a few minutes to diagnose with a couple of hints thrown their way. BTW, if you manually switch presets on the front panel during a run, say from SDDS to SRD to Optical, etc., do you also hear a pop in the monitor? And if so, when? (Coming or going to/from which format? I'm going to guess that if the answer is yes, it is coming and/or going to/from the Optical preset, but make sure the print is playing all three formats you're configured for if you check this).
Firmware version for all D3000's should be v2.92, changeover delay should be set for 7 seconds. I'm reasonably sure that all the units at Prescott are at v2.92.
The issue of crossfade is actually both firmware & hardware related. Newest generation DSP's use a newer generation processor. Since the new processors had some extra horsepower, a new firmware version was compiled strictly for the new boards which took advantage of the extra HP to perform the crossfade.
With or without crossfade though, there should be no inherent pop in the transitions of a properly funtioning D3000. A quick swap of the APR-34 (bottom) board or the DSP-82 (top board) in the processor (with a non-popping unit) will localize the pop source to either something failing inside the processor, or some offset present at the optical input. (This is definitely a to-do for your tech only).
FYI, the D3000 has it's own flavor of hold-time algorithm to prevent switching in and out of digital repeatedly, so rapid switching in and out is probably not the cause of the pop.
And you're right, Cyan optical tracks have nothing to do with SDDS decoding or sound quality. Although, if you're doing your own A-Chains as you mentioned, it would be interesting to know what the Slit Loss EQ is set for on those houses right now (that will show on the same screens as your Lt/Rt level cal).
As a last bit of info, SDDS can play through splices without any analog reversion since the two SDDS tracks are physically offset from each other by 17.84 frames. So there is no "splice noise masking" function in the unit at all. However, if you're reverting at a splice it means that TWO ACMs (or two double-track errors) have occurred within the 17.84 frame window in order to force the reversion. This is one of the reasons why splice quality is so critical, since a (for example) 39mm wide splice passing through a 35mm roller might cause enough of a physical impulse to create a second error near the splice point. Similarly, excessive handling around the splice (which causes any damage) can cause an error within the 17.84 frame window. And Brad has already touched on the influence of any physical alignment issues, and how to isolate those. Ideally, the unit should be playing through splices without analog reversions at all.
Tell the guys to give me a ring next time they come up there though. It won't be too hard to find the source of the pop.
-- Robbie
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Michael Schaffer
"Where is the
Boardwalk Hotel?"
Posts: 4143
From: Boston, MA
Registered: Apr 2002
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posted 05-02-2005 01:22 PM
A "weekend" is when people don't have to worry about work and have a good time. Kind of like ShoWest, only that normal people have it every week.
Alan: Since the pop problem obviously comes from the sound processor(s), an even better way to listen for it is using the DFP's headphone output. The selector switch can be configured in the software, the positions can be assigned various channel configurations. I do not know if you are allowed to use the software or to access the settings via the front panel menu. If not, ask him to configure the headphone settings for you.
The changeover settings mentioned by Robbie should absolutely be checked. We had a few DFPs which dropped out at every splice until I set these to 7 seconds for both - even though it was a platter setup - projectors. Then it worked very well...
Even if you are not allowed to use the software, you can check the firmware version any time by pressing the down arrow, then right, select menu when it is flashing, select status, the version number is right there.
I am a little confused about when exactly the pop occurs. When the system drops out and switches between formats, when it has already dropped out and is in Dolby Digital? Dolby Digital sometimes makes a very short "eee" buzzing sound at splices, I don't think there is anything you can do about that. Or does it revert to analog and the pop occurs in analog at the splice? Again, no offense intended about your splices. I just want to clarify where exactly the problem is.
I am little more confused by you mentioning that you have BACP penthouse readers. These are excellent units (Sam got the recognition he deserves for the design by every city in California naming a street after him), but if you have a Kinoton projector, you don't need it. The basement reader is just as good, and upgrading it to D costs $1000 less than buying the BACP penthouse, in addition to the fact that it is doesn't add any rollers to thread and clean in the film path. So a lot of money was wasted in the planning of your location...
That leads me to one more thing to check that wasn't mentioned before: Are the SDDS and Dolby reader offsets programmed correctly? It may be that they are just a little bit off and what you hear when the DFP switches is the audio "stumbling" for a moment. This is best tested by listening to a high quality piece of film (not a trailer) with dialog over the headphone. After threading that (the film, not the headphone) carefully with your standard loop sizes, select the C channel and switch between analog and the digital formats. The audio must be exactly in sync. If not, the reader offsets have to finetuned.
What I meant earlier by the "A" adjustment was not the traditional A-chain, but hooking up a notebook to the reader and sending it a textfile with the message "A" (for "adjust") via HyperTerminal. This will make the reader go through a self-adjustment routine.
Finally, if you are interested in troubleshooting print problems with SDDS, download the Lab process manual from the SDDS website. It explains exactly what channel information is in which track, how they are offset etc. It also contains high-res pictures of the actual track. Looking at the tracks with a magnifying glass can be very revealing: Sometimes the edge markings are washed out. Sometimes you find that the tracks are offset horizontally, so that the track on one side doesn't even have the edge marking anymore (typically on the picture side).
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All rollers on the readers roll freely. All 3 sound drums are nice and clean as usuall. If all else fails I'll have Andy try the "swap it and see if problem follows technique" on the Cards in the 3000's.
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