Dolby CP850 used

[Marco Fantino]

Good morning,
I’d like to buy a used Dolby CP 850 from Japan.
we will use it in a post house in 5.1 o 7.1, not Atmos.
we will connect via aes/ebu db25 and the output through analog.
Do we need any license from Dolby? Do we get full menu for calibration, eq and delay?
Thanks for your help.
Marco

[Marcel Birgelen]

We used a CP850 for screening-room and post-production purposes in the past, but we migrated to an IMS3000. You need the Atmos license for Atmos. If you're not doing Atmos, then it's fine. You get access to the full calibration options. Actually, for 7.1 and 5.1, the CP750 would be equally fine and probably cheaper.

Since we run the room in multiple configurations we use QSys for signal routing and calibration, which has been far more flexible than just relying on the CP850.

[Marco Fantino]

Thanks Marcel. We choose the 850 for the hdmi In and OUT usable for color grading as well with projector. Any concerns about the HDMI on 850?
Thanks

[Leo Enticknap]

I respectfully disagree with Marcel that a CP750 would be just as good, given the two known issues with the 750 (the power supply board borking out and "level drop disease"), which, combined with replacement motherboards and power supply board no longer being available, effectively mean that any remaining units in service are now pretty much on death row.

There is a known issue with the HDMI interface on the CP850, which is that if it is used intensively, the logs can fill up, resulting in erratic behavior, e.g. API commands not executing, or even the unit freezing up completely. At one site where I ran into this, Dolby advised us to power cycle the CP850 weekly. We configured a WattBox to do this automatically, which solved the problem. If the HDMI input is not used at all, you don't have to worry about this: the CP850 can be left on indefinitely.

As a very rough rule of thumb for both the 850 and the 950, using the HDMI input or loopthrough is solid and reliable at up to 1080p/4:2:2, but if you try to go above that, there can be dropouts and EDID exchange glitches with the display device on the other side of the loopthrough. I would always want to feed HDMI into one of these processors from a separate, fully independent output of a scaler (not a simple switcher whereby the EDID of the least capable sink determines the output format from any given source) if possible. And of course the HDMI input can only disembed LPCM or Dolby audio; no DTS.

[Steve Guttag]

The CP750 power supply is certainly obtainable. We also still sell an external CP750 power supply. In fact, I'm less inclined to replace internal supplies since they just put more heat in the "box" to work against the motherboard. But I agree with Leo...CP750s are in the "when" not "if" they are going to fail category, at this point. Now, I'm sure that someone could probably determine the main points of failure, output decay and could come up with a solution there. There are a LOT of capacitors on that motherboard. The outputs are standard ADC differential outputs (look on the bottom of the board). It is a shame that Dolby never really fixed them so there is no good troubleshooting guide of "if this failure, replace these components" sort of thing.

CP850 HDMI port is HDMI 1.3 (maybe 1.4). The CP950 is HDMI 2.0 and configurable to HDMI 1.4. I have had EDID issues on the CP950 where things needed to be unplugged/plugged...so I'm not too jazzed about its robustness. Then again, I've had many things in cinema be less than rock solid with HDMI interfacing. As Leo points, out, the CP950 understands Dolby and LPCM...no DTS.

[Marcel Birgelen]

I'm not aware what the current supply is, but the CP750 was rolled out to tens of thousands of screens world wide, whereas the CP850 ever only saw a roll-out in premium theaters. Last time I checked I could get a "refurbished" CP750 for a few hundred bucks, the CP850 was much harder to get and for a multiple of the price as a refurbished model.

From a practical point of view, if I'm operating in what I'd call "unsupported ghetto mode", I'd go for one or two CP750s on the shelf alongside the production unit, instead of one unsupported CP850... But that's how I always operated if I didn't have the budget for the "fully supported" mode.

Eventually, once you can afford it, you'd probably want to upgrade to a CP950 or IMS3000, like we did.

Thanks Marcel. We choose the 850 for the hdmi In and OUT usable for color grading as well with projector. Any concerns about the HDMI on 850?
Thanks

Frankly, I've never used the HDMI-out of the CP850. We're currently using a bunch of BlackMagic/ATEM HDMI and SDI switchers. We've also have a bunch of HDFury devices like the Vertex and Vertex 2 to do some HDMI-splitting magic, like splitting the sound and video bitstreams and routing them to e.g. the CP850 and the projector directly.

We have two projectors, a Barco SP4K and a DP4K machine. We only use the xenon machine for color grading. Both machines have an IMS3000, only one does have an Atmos license at the moment. We're using either dual 3G-SDI or HDMI 2.0 REC2020 as input when color grading directly out of a PC. The output from the BlackMagic card in the color grading machine, running Davinci Resolve outputs directly into the IMS3000. Audio is usually routed via another HDMI interface. When it comes to color-grading, I want to limit the stuff between the output and the projector as much as possible, in order to avoid conversion as much as possible. The Rec2020 to DCI P3 conversion has been accounted for in the setup. If possible, I'd prefer to run 3G-SDI, but 4K modes are currently not supported via that route.

Barco is currently rolling out their Post Production P/P+ series including their "calibration magic box" at horrendous prices, but most professional color graders don't seem to be convinced.

For DTS support, we keep a venerable Datasat AP20 around, but the need to support DTS is rather minimal, that's why I'm considering removing it from the rack, also to free up some analog inputs on QSys.

[Marco Fantino]

Thank you very much for your useful infos. Really appreciate.
Hope buying in Japan from Europe will be fine.

[Ioannis Syrogiannis]

[...]Do we need any license from Dolby? Do we get full menu for calibration, eq and delay?
[...]

Well, not with the "operator" credentials.
And with the elevated access, you will probably need more than the one microphone and sound pressure reference for X-curve calibration.

If it's anything like the CP950 on that matter, you will need the Dolby Atmos Designer in order to design a configuration, even if you are only setting up 5.1 or 7.1. The up-side is that you can also use the autoEQ.

[Leo Enticknap]

I would guess that by license, Marco means a file that is uploaded into the unit to unlock features. If so, the answer is only for Atmos.

I can't remember for absolutely sure, but my recollection is that the CP850 and 950 are similar in that you do not need to use DAD if you only need a regular 5.1 or 7.1 output, do not need AES67 or BluLink output (just analog), and do not need to use the internal crossover (all channels come out full range). If you do want to use any of these features, you need to create a DAD design. If you want to decode IAB, you also need the Atmos license. Obtaining it isn't as simple as writing a check: you have to create a DARDT spec for the room, which Dolby has to approve, and then after you've installed everything ("commissioned" is the verb used in Dolby's training material), send them a packet of evidence to prove that the room has been created and the system installed as designed, and only then will they issue the license.

As Ioannis notes, you need the administrator login credentials to configure and tune. If Marco doesn't have them, I would suggest emailing cinemasupport [at] dolby.com.

[Christos Gartaganis]

Worth mentioning that the CP850 is no longer supported by Dolby so replacement parts, including the power supply brick, are not available for purchase in the event of a malfunction.

[Marco Fantino]

I would guess that by license, Marco means a file that is uploaded into the unit to unlock features. If so, the answer is only for Atmos.

I can't remember for absolutely sure, but my recollection is that the CP850 and 950 are similar in that you do not need to use DAD if you only need a regular 5.1 or 7.1 output, do not need AES67 or BluLink output (just analog), and do not need to use the internal crossover (all channels come out full range). If you do want to use any of these features, you need to create a DAD design. If you want to decode IAB, you also need the Atmos license. Obtaining it isn't as simple as writing a check: you have to create a DARDT spec for the room, which Dolby has to approve, and then after you've installed everything ("commissioned" is the verb used in Dolby's training material), send them a packet of evidence to prove that the room has been created and the system installed as designed, and only then will they issue the license.

As Ioannis notes, you need the administrator login credentials to configure and tune. If Marco doesn't have them, I would suggest emailing cinemasupport [at] dolby.com.

Usually we rent a movie theater, to close the audio mix, with CP750. Everything is already calibrated. Actually we are building a new mix room in our post house. Without a Dolby license (keep in mind that we do not need atmos) what will be not possible to adjust? Unfortunately, we have never bought a used CP and we would like to not waste money.
Thanks again
Marco

[Christos Gartaganis]

Usually we rent a movie theater, to close the audio mix, with CP750. Everything is already calibrated. Actually we are building a new mix room in our post house. Without a Dolby license (keep in mind that we do not need atmos) what will be not possible to adjust? Unfortunately, we have never bought a used CP and we would like to not waste money.
Thanks again
Marco

Marco, you still require an acoustics consultant and an audio engineer experienced in calibrating Dolby processors or similar equipment to properly calibrate your mixing studio. This is mandatory to meet the SMPTE X-curve standard used in cinema sound systems worldwide, especially in dubbing and review rooms, to guarantee consistent audio reproduction. You should also avoid using near field monitor speakers in your new mixing studio.

[Elia Orselli]

Usually we rent a movie theater, to close the audio mix, with CP750. Everything is already calibrated. Actually we are building a new mix room in our post house. Without a Dolby license (keep in mind that we do not need atmos) what will be not possible to adjust? Unfortunately, we have never bought a used CP and we would like to not waste money.

You don't need any license to operate the processor in standard 5.1/7.1 mode, but you need tools and knowledge to calibrate it properly. Are you sure it's cheaper an used and EOL CP850 from Japan than another solution? CP950 is not suitable if you need multi channel input, but a Trinnov Ovation2 would be a very good choice. Or QSYS, maybe.

Non servono licenze per usare un cp850 in modalità 5.1 o 7.1, ma - in ogni caso - serve avere la strumentazione per la taratura del processore e la formazione per farlo. Visto che l'850 è fuori produzione e anche i ricambi sono in gran parte non più disponibili, può essere saggio optare per un processore nuovo. Il 950 non è un'alternativa valida se dovete usare l'ingresso multicanale analogico, dato che ne è sprovvisto, ma un Trinnov Ovation2 potrebbe fare al caso vostro (e se vi può interessare, sono il rinvenditore italiano), o una soluzione QSYS potrebbe essere altrettanto interessante.

[Stefan Scholz]

I have also seen the bay offers, different vendors from different locations using the same images to sell their product. And different prices from lower to higher.
I did not trust it. They were asking from 1200 to 1600 bucks per unit.
CP 850 is End Of Life, so spares are difficult to get. Atmos licenses had a 10 year certificate validity, can it be extended?
How much is the saving (shipping and import duties included) over a CP 950 without Immersive Audio media block and beefier power supply, brand new including manufacturer support and warranty?
As you are not needing the Atmos feature. You do not save anything at all.

[Dave Macaulay]

Agreed. Base 950 with warranty and support for some years is a better idea. 850 is a good unit but you're paying to power the Atmos processor and hoping nothing fails soon. It does have advantages for AES67 distribution but for an analog system the 950 has been great for us. Unless you absolutely need a multichannel analog input.