Help with the path of our sound

[Brian Mendelssohn]

Hi all.

Wasn't sure how to title this, We are installing a reel to reel Norelco 70/35 system. All of the audio is going into a Dolby 650. Perfect! Separately in the same booth, I have my digital system (christie 4435) going into a Dolby 950 Processor through the two RJ45 AES ports. All of my amps (dumb QSCs) are connected to my 950. All of my JBL speakers are bi-amped with the equalization and crossover happening in the 950.

Of course I don't want a second set of amps. I want to tie my 650 into my amps also. I figure I have two paths

1. 650 into the 950. since my 650 model doesn't have crossovers, and the 950 doesn't have analogue inputs from the 650, I need some kind of analogue to digital converter. I could run that digital conversion into the HDMI port or the two RJ45 AES ports (and just manually switch the cat6a cables from one source to the other when I'm running film or digital). Maybe there is even a AES Rj45 switcher out there where I hit a button going from "film" to "GDC1000" but that is a minor add.

2. The analogue output from the 650 can go into a crossover device to match what I have in the 950. I get the 650 equalization to match the 950, and have some kind of analgoue audio switcher. Specifically the 950 output and 650 output both go into this magical switcher. The switcher's output then goes into my amps.

I wanted to get the boards thoughts on the best practice here and any products they would suggest.

I really don't want to run the digital audio to the 650, and I'm hoping to not have to get a datasat ap25 processor to solve this either.

Thanks in advance. I hope this is clear. Can't wait to show our first 35mm in my theater.

Brian
Row House Cinemas.

[Marin Zorica]

Tought one! I have few installations with combo 35mm and digital. Few have datasat AP25 because it supports 35mm, where some are using datasat optical preamp, some cp650 which is set to flat and feed thru AP25, and other with qsc core ti manage all.
On you're case, yes it would be possible to use hdmi embander and emband 650 5.1 to hdmi and feed it to cp950. I did that few times when somebody ask for extra non sync input. Another idea, maybe, it would be to have switch between christie aes and (but as i know they are very rare) card for 650 to have aes outputs, or to convert 650 to aes.pairs. It will have more headroom and better s/n ratio than with analog to hdmi embander and this would be best as it have minimum degradation over any else. And last, to have separate eq in 650 and made small board for switching between 650 and 950. I use small takamisawa signal relays and it is flowless. Last time i've had similar situation with 950 was nultipourpose room, where left, right and subs are actualy main speakers from pa, but that is tricky as you need extra xover.

[Marcel Birgelen]

The problem with HDMI embedders is: there are plenty of cheap embedders out there that will happily embed stereo audio for you into HDMi, but not so much that will embed 5.1 audio. The lack of a multi-channel analog in on the CP950 really is and remains a major bummer.

QSys with the necessary interfaces could solve this easily, but it's certainly not a cheap solution and still requires some considerable configuration. I guess one of the cheaper solutions will actually be an AES/EBU matrix switcher. Most of them use AES over XLR, but nothing that some creative cabling couldn't solve.

[Marco Giustini]

Avoid HDMI like plague, IMHO. It's a big can of worms.

I'd go with an AP20/25 or QSYS to convert audio to AES. QSYS can also be the switcher here.
The CP650 digital AES output could also work but it's rare.

[Brian Mendelssohn]

so you think the best solution would be to replace the 650 with a datasat. Its an expension solution but works. I just assumed this is a common issue?

[Tj Hopland]

Does your 650 or any of your spare 650's have a Cat 790 board? If so that is the AES input board so the 650 could then take 8 channels from your server and do 7.1. You would just need to deal with crossovers which these days there are several options, many not that expensive. Dolby also did make a crossover board for the 650, I don't think it was super common but maybe there are still some around? This would be fairly clean and conventional. Down sides would be HIVIN from the server would have to be dealt with externally and even your digital shows would be depending on a 25ish year old computer with no official support. With film that is typically fewer shows and is depends on many other old unsupported things its just part of the deal but since in most venues there are more shows that are digital and you can get new and fully supported digital equipment there is some logic in having the 650 only do the film side of things.

Are you doing Atmos? If not then maybe look at getting rid of the 950? Which I guess I sort of already covered one way of doing that in the first paragraph. Trinnov has the analog inputs and can do internal crossovers, I think that may be the only cinema specific processor you can buy new that still has the inputs. The QSC DCP series were fairly common and reliable and had the input so maybe looking for one of those would be an option? Kinda gets into that unsupported territory again but I would not think it would be too hard to find a couple of them so you could have a spare and then that will give you more options than if you just had the 650 alone. Hook up is also easy if your 'dumb' QSC amps are DCA or ISA. 750 had the inputs but at this age reliability and support isnt there.

For a non standard movie theater the Qsys platform is really attractive because its flexibility and scalability. You would have to get someone to do a preliminary design but it may be possible to start out keeping your existing amps which could help with the initial cost. Once you have the platform you can then keep expanding it as needs and budget come along. You mentioned JBL speakers so maybe your dealer prefers Harmon products they also have a similar platform and I think just recently came out with a scaled down and less expensive version of it that would likely be a good fit for theaters. Their original one just like QSC's was really intended (and priced) for a much larger scale than a screen or three that we are typically doing. The custom interface, automation, and remote controls you get with these platforms can also be really useful for a non standard movie theater or multi use venue.

You mentioned 'dumb' amps. Maybe a path would be getting some 'smart' amps? Lots of them out there these days and some I think can be configured and remotely triggered between different presets so maybe it would be possible to do something like then move the crossovers to the amps which then frees up inputs so as an example output 1 and 2 are your center LF and HF. Assuming the amps internal software allows it which I'm sure some do and some don't you have input 1 be center from the 650 and 2 be the center from the 950. Both signals get routed to the crossover that then does its thing and then out to the speakers. I guess you would in theory not even need to mute the inputs you were not using so no remote controls needed you just have to make sure you mute the output of the processor you are not using. Seems like this approach should be reliable compared to some sort of inexpensive external switch. I'm sure reliable high quality switches are available but they are not going to come cheap so spending that money on a smart amp may make more sense and open things up for future improvements?

Lots of options really it just depends on budget and longer term goals.

Not likely going to be an option these days but Dolby did make an optional digital output board for the 650. From memory cat 778? Original slight catch to that option was you lost all the analog outs including HI so you could not do a mix of analog and digital outs like you can on something like a 950 today. Big catch today is finding one and if you did find one I doubt you would be lucky enough to find a second one to have as a spare. I would be surprised if they even made 100 of em. At the time it was just a few studios situations that could use and wanted that option. if anyone has one of these now and knows what they have they are not going to be giving it away so at that point that money is maybe spent on one of the above options rather than into something this old that isn't even all that flexible. Now if you were looking at an auction site and saw a 650 upside down with a poor description mixed in with office furniture and the stuff is or was located in LA? Maybe it was a closed lab or studio lot and you could score it cheap. Still pretty unlikely tho........

[Marco Giustini]

you do NOT want the 790 of a CP650 to be the core of your system, it's notoriously unreliable. And to be honest, you don't want a 20 years old sound processor to be the core of a modern system.

No, I suggested the AP20 as a Analogue to Digital converter (analogue from the 650 to AES). I know, it's a waste but a few years ago it was the cheapest solution as a PROPER analogue to AES device was not cheap. The AP20 can do Dolby SR with an additional board but won't do Dolby Digital and nothing beats a CP650 on those tasks.

[Ryan Gallagher]

Short of automating an analog or AES matrix switch, the AP20/25 and or QSYS (possibly Trinnov?) approach being fed by a 650 has run of show advantages too, You can more easily run shows that mix digital and film content, automation is built into the solution. All depends what features of you 950 you use or plan to use?

I know swapping or adding a processor was not your wish, but budget and needs depending it might make the most sense?

[Marcel Birgelen]

While I generally agree with Marco that you should try to avoid HDMI in professional setups, unless you want to fundamentally change the way audio is routed in your system, the cheapest solution would be something like the ATEN VE66DTH, which can embed 6 separate MONO sources into both Dante AND HDMI, although the specs remain vague if it actually supports 6-channel PCM over HDMI with the current firmware. That HDMI signal can be fed into the CP950. You'd only need to build a special cable between the analog output of the CP650 into the inputs of the VE66DTH.

With a list price of about $1200, this would be way cheaper than introducing QSys or an AP20/AP25, both when considering equipment and installation costs.

If money is no objection, I'd probably redesign the audio core around Q-Sys. Feed the digital audio from the CP950 into the QSys system via AES67 and the analog audio via analog inputs on the QSys core and do the crossovers in QSys too.

[Tj Hopland]

If he doesn't already have a wish list that would seem like a good place to start. Throw out the tight budget and knowledge of specific equipment, what do you wish you could do? Stat there and work backwards to the budget and tech. That exercise can really help come up with a longer term goal so you can make the best choices along the way.

That ATEN piece seems like it could be a reasonable way to get started to get the 650 into the 950 via the HDMI but doesn't seem that likely to be the final solution. Do you currently use the HDMI function on the 950? If no then thats another point in favor of this option. If yes then that is points (possibly several) against the option. I would not go this route if there is any switching or re plugging involved. HDMI can be OKish if its a single out going directly over a single fairly short cable to a single in. Every and anything you add to that chain increases the chances its not going to work. Sure it may work the first time when you test it but when you have a full house.........

I have never needed it so have not looked but does the 950 actually have 8 pairs (16 channels) in? Or did they cheat and its 10 or 12? And if its all 16 then does the software let you patch em anywhere? Or do they limit you to what would be considered typical options? If so maybe that would be an option? Your DCP is using 10 channels (assuming 7.1 and HIVIN), that leaves 6? So how much is a 6 channel A to D ? If the 950 supports routing things around that way you could still have the HDMI available for the usual HDMI video as intended.

IF its got the 16 channels and IF it lets you do the routing an additional possible catch is will it let you 'split' those inputs? Or is the clocking for all 16 tied to a specific pair? I'm thinking if you can split em its gonna have to be 8 and 8 so you will have to get your 7.1 from the server all coming down the 1-8 set then the 650's stream will be on the 9-16. HIVIN from the server will have to be handled externally but we are not talking multi channel hi fi that needs crossovers and EQ so that should be a fairly easy thing to do even if its an analog system.

I know there are a lot of IF's there but IF there is 16 and IF the routing isn't limited and IF there isn't some thing with the clocking that doesn't allow 2 sources and I guess the 4th IF is IF a 3xAES3 A to D doesn't cost more than the other options maybe this would be a reasonable route?

[Tj Hopland]

Just reading more of that ATEN before I closed the window I had open to see what else it could do and are we sure it will embed analog to the HDMI? It says it will embed Dante to HDMI. I have never used one and wasn't reading the manual, just looking what was written in the overview. It may do it I just want to make sure someone can verify it before someone gets one and finds out they would really need something to first go analog to dante then this to go dante to hdmi. You would think it could since it can to the important bits on each end its just did they give that option in the software?

[Marco Giustini]

very good point.

I see mentioned multiple times that HDMI is only Stereo.
Screenshot 2026-01-10 233553.png

[Marcel Birgelen]

Yeah, it seems the device cannot do 6-channel LPCM over HDMI. Apparently, the number of devices capable of embedding 6 channels as LPCM over HDMI is pretty limited... I've found this device, but specs are, again. inconclusive.

[Tj Hopland]

Its a great idea and you would think there would be other applications for such a device but apparently not. I briefly looked into it a few years ago for a similar application and it went kinda like it seems its going now, very expensive or inconclusive.

Too bad Dolby doesn't offer some sort of legacy input board that could maybe go in the Atmos slot of the 950. I get why they would not want to mess with more oddball stuff like noise reduction and a proper optical preamp but some more analog and maybe even digital inputs could be handy for some people and I would think would be 'off the shelf' hardware.

Maybe this is a new product idea for someone to come up with, a DMA8 / ECI-60 sort of product but instead of 'patching' into the analog path that was used by the likes of DTS and SRD it patches into the AES path? Its got 2 RJ45's in and 2 out. Server goes to the ins and then you run a pair of cables from this to your CP. In 'bypass' mode it does nothing just like 'film' mode did on those old machines. When you engage the other modes you get things like the multi channel analog input(s) and the CP won't know the difference.

[Steve Guttag]

Ironically, the CP650 is more suited than your CP950 for this. That is, the CP650 is capable of playing both digital cinema and, of course, film based audio. That said, I won't put digital cinema into a CP650 anymore as the CAT790 card used for AES3 from digital cinema is somewhat defective and will result in "Robosound. The other reality is that the CP650 is aged and in the event of a failure, your solution to fix it will be another CP650 for parts and/or kludging a power supply, if that is the point of failure.

Maintaining two discrete paths of crossovers and EQ is a foolish one that has one doubling the work and doesn't integrate well. You could, I suppose, make an elaborate relay bank and feed the CP650 and the CP950 into the relays to share the amplifiers. It just isn't what I would do.

The problem in your system is the CP950 and its lack of a suitable input from the CP650 (or another processor). I think you'll be happier replacing the CP950 with a more suitable processor.

• The Datasat AP25 has the unique advantage of supporting both film and digital cinema with a degree of customization for control. It gets your entire operation into one box. The AP25 has an HDMI switcher and decodes DTS. This may be a benefit, if you do Blu-ray shows and can aid in any laptop type performances. The AP25 is getting on in years, if you take into account that the AP25 was a necessary refresh of the AP20. I wonder how long it will remain in production but it has a strong following.
• The Trinnov OV2 lacks HDMI inputs but does have multichannel analog inputs and its handling of speaker crossover and voicing are considered tops. I defy you to find a single person/company that has one to speak ill of it. The CP650 would feed its multi-channel analog input as a source.
• Technically, the QSC DPM300/H gets you the inputs you need and, if you have QSC DCA amplifiers, a means to just plug in via data port cables and you could take advantage of "Intrinsic Correction" if you are using QSC speakers (now handled by MIT). The DPM line is a very rigid/purpose-build box and the least flexible of the options.
• And then there is the most flexible one of them all, Q-SYS. Even the smallest of the Cores handles up to 64-channels in and out. It is flexible and can be perpetually "right-sized" to your needs. It is the most feature laden in terms of audio, control and video. However, if you don't plan to take advantage of of those features, then you are paying a premium to get a basic processor. Since you have a Norelco DP70, that opens you up to 70mm (presuming you have the 70mm parts)...that also means that you'll want a DTS player of some sort. With Q-SYS, just connect that up to another set of analog (or digital, if you have suitable outputs on an XD10 or XD20). And that's the thing, you get to size it to your needs, as your needs change.
  
  Now, who will be designing the system and configuring it could be you or someone else but it will take some degree of effort since it is not "canned." You start with a blank slate though you can get a system up and going pretty fast. And, if you like it, you can have a single system handle all of the screens in your complex, with redundancy to ensure you don't go down. If you go over to the Q-SYS Corner thread, you can read my various blogs that might give you some insight or ideas on what Q-SYS can do for you (or if it really isn't the direction you want to go).