Dolby Multichannel Amplifier

[Darin Steffl]

Is anyone using this in their Theatre? We're 5.1 now with 3 amps but looking to go 7.1 and bi-amp all channels which means the DMA16301 would be our best bet. We already upgraded to a CP950 processor so the analog inputs now would move to ethernet and we could remove our booth monitor since the CP950 has one built in.

Just wondering about performance, reliability, and warranty. The huge downside is if this one Amp dies, we lose all audio instead of having multiple stereo amps where there would only be partial audio loss if an Amp dies.

https://professional.dolby.com/produ...mplifier/#gref

[Marcel Birgelen]

Most stuff in cinemas isn't really redundant... most have just one digital projector, one server, one audio decoder, so why not add another singe point of failure?

If you already have a CP950, I guess it's a fine upgrade all in all.

I have only heard them in action twice, so I can't say anything definitive about sound quality, nor reliability.
I know that a lot of people don't like Class D amplifiers and the early model Class D amps frankly were mostly rubbish. That being said, professional, modern Class D amps are usually perfectly fine.

[Steve Guttag]

I haven't started using them...yet. However, they tick a lot of boxes. If they had a better AES67 implementation, I probably would already have used them. There is a lot of backup already in them. There are multiple supplies and processing. To lose the entire amp (all channels), you normally have had to have lost two things already. If a power supply goes down, it keeps going, if it has to throttle things back, it will (power shed) to keep the more important channels going.

It is mostly field serviceable. So, unlike most amplifiers, where, if it goes down, the DMA can have board swaps in the field. Heck, it has slides just like the old servers. The one area where I wished they had come up with a better way was the output modules...they remove from the side so...those slides I just mentioned...yeah well, slide it out all of the way, remove the one slide to open the cover to remove the amp module. But, at least you can replace that module, in the field rather than shipping things back.

If you are going to adopt the DMA as your standard amp and use it on multiple screens...have a spare in the booth. Then you could slide one out, slide the other in...repair the bad one on the bench so it is ready for the next time.

As Marcel aptly mentions, you have a lot of single-point failure systems in your world already. We've come a long way from the days of 2-projectors, tubes or plug-in modules, AC switches for exciter supplies and the notion of "the should must go on." However, if exhibitors could take a part of what they used to pay projectionists and put that money into spare components, it could lessen the impact of a failure. Naturally, this works best with a scale of multiple systems.

[Carsten Kurz]

Personally, as an independent operator, I would never make myself dependent on such proprietary solutions. We do have backups/spares for every key component - well, not for the building ;-)
I have no idea about reliability figures for the Dolby multichannel amp. As Steve says, it has quite a bit of redundancy built in already. Maybe there are ways to keep your existing amps as backups at least for the screen channels. Don't know how much effort it would mean to switch the 950 between the two amp types in an emergency.

[Darin Steffl]

Personally, as an independent operator, I would never make myself dependent on such proprietary solutions. We do have backups/spares for every key component - well, not for the building ;-)
I have no idea about reliability figures for the Dolby multichannel amp. As Steve says, it has quite a bit of redundancy built in already. Maybe there are ways to keep your existing amps as backups at least for the screen channels. Don't know how much effort it would mean to switch the 950 between the two amp types in an emergency.

It would be possible. We would just leave the analog stuff alone and in the rack, keep at least two amps for the stage channels and sub, then move wiring around and change a setting on the CP950. This seems like the best way to have a backup without buying anything new since the gear is already here.

Looking at us upgrading to 7.1 and wanting to wire for 2 way speakers on stage, and bridging the sub and surrounds, we would need 16 channels to achieve this. It looks like the 16302 is a little over $5k but doing this with QSC DCA 1622 amps would cost us over $6,500 at current priced we've been quoted. Going with 8 amps would also require more wiring, more rack space, more power circuits, etc.

The DMA seems like such a good solution. Hopefully somebody on the forums has one in their Theatre and it's not just the big players who have them.

[Dave Macaulay]

We have used DMAs in an Atmos room. One output module failed early but no issues since then.
You have to be careful with loads, the chassis PSU has a power limit so don't assume that it can output full power on all channels simultaneously. We used two DMAs and had to balance high power loads (LFE & subs) between them.
The CP850 to DMA digital audio interface has been no trouble at all.

[Scott Norwood]

I've never seen one of these, but, out of curiousity, what is the selling point versus regular 2-channel or 4-channel amplifiers from QSC, Crown, etc.? Is it cheaper? Easier/faster to install? Something else?

[Darin Steffl]

I've never seen one of these, but, out of curiousity, what is the selling point versus regular 2-channel or 4-channel amplifiers from QSC, Crown, etc.? Is it cheaper? Easier/faster to install? Something else?

Cheaper per channel, way less space, Web GUI to manage it and look for faults, easier to install. If you have a CP850 or 950, the input is a single ethernet cable instead of analog cables. 16, 24, or 32 channels in 4U of space which would normally require much more space for individual 2 or 4 channel amps. In our case, 8 of the 2 channel QSC amps would take up 16U vs 4U for the Dolby for the same number of channels. We can also just run one 240V, 20A circuit to the Dolby vs. many 120V, 20A circuits for 8 regular amps.

The downside is another single point of failure but we'll remedy that by keeping at least 2 existing amps in our rack so we can switch wiring over to it and keep the stage speakers and sub running.

[Randy Stankey]

While I'm sure that this Dolby product is good, I'm sorry, I just don't like all-in-one devices.

As others say, it's a single point of failure. That's not good.

Back in the 90s, I used to work at a store selling TVs, stereos and home electronics. Back in those days, all-in-one TV/VCR combos were popular. I used to tell every customer that, as nice as they seem, if one part of the unit goes down, the whole TV has to be repaired or scrapped and replaced. Still, people bought them.

Probably about a third of those combo-TVs would come back for warranty service within the 90/365 warranty period. (90 days parts+labor. 1 yr. parts only.)
A significant fraction of the sales receipts (required for warranty service) on those items had my name on them. I know that I told those people about the consequences of failure because, whenever I sold one of those, I'd underline the warranty statement at the bottom of the receipt when I warned the customer.
(This scenario repeated so frequently that I developed a code so that I would remember if I told them.)

Almost every customer who brought one of those back for repair would complain that they didn't have a TV just because the VCR was broken.
The store policy was to replace only for DOAs or soon after. After that, it was repair first then replace only if the repair shop said it was a goner.

After having to stand there, broken hearted, to see a customer unhappy with their TV, even after I know that I warned them, I just resolved to never buy any kind of all-in-one system unless the benefits were so good that they outweigh the consequences of failure or unless the device is being used for a non-critical purpose where it doesn't matter.

In a movie theater where amplifiers are mission-critical, I would never recommend an all-in-one.

[Marin Zorica]

Few units around here are ok, but they all used in smaller rooms. Plus, as recomended take good look when doing setup not to over load it with max power, as you cannot just take for example max power on each channel x16, because you're limiter bg power supply. Also, try to check some 4ch or 8ch amplifier with network like crown dci, powersoft quatro or ottocanali or something else and try to compare prices. You would still have audio over ethernet (blu link, aes67, supported by cp950) and two amplifiers so you can always swap is something goes dead, to power just front speakers so you can run the show.

[Stefan Scholz]

It's no a bad idea. I've been using 8 channel amps for long in my surround installations, and they rarely failed. Plus helped us save a lot of space. I do individual biamp channels per surround.
From what I learnt on the provided Dolby training material, it is quite safe and has ample enough backup to help you stay in business. Yes, it can't provide maximum rated power on all channels, if it's a fully equipped chassis. So if you need more power (use efficient speakers), order lesser channels.
The only point I have is the AES 67 implementation, which is not that perfect, compared to others.
But with a complementing product from the Dolby ecosystem, it works perfectly nice.
I like the advantage of the simple installation, networked audio is a time saver over individual analog routes.
It is one option on the market, and there's more than that from different vendors.

[Darin Steffl]

Our one screen already sounds amazing with three 2-channel amps in a 5.1 setup so going to the DMA 16302 will have more available power overall with a 240v circuit, 20A. We just placed the order today and hope to have it installed in a few weeks. We'll convert to 7.1 at a later time when we replace our curtains inside and have access behind things.

The reason we're upgrading is because our QSC MX1500a amps are starting to fail on certain channels. So instead of replacing individual amps, we thought lets just go all new and start fresh with our audio.

I'll stop in here and update how the install goes and any likes/dislikes. We're excited to clean up our sound rack a bit and get rid of all analog input wires and move to a simple ethernet cable.

Thanks for all the information!

[Leo Enticknap]

I've only installed one house with them, an Atmos auditorium that has two DMA24302s, and one DMA32301 (processor is an 850). The firmware they shipped with (3.0.0.18-4758270) had two significant glitches: the unit would freeze and require power cycling while trying to download a log package, and it would throw false positive fan failure errors. Upgrading to 3.0.1.2 fixed both problems.

Apart from that, they tuned up fine. The installation was in November 2018, and I haven't heard anything from the customer since, so I presume that he's happy with them. Each channel or pair of channels (can't remember which) has its own power amp card, which are independently swapable in case of failure. So that architecture mitigates the single point of failure risk a little bit, especially if you choose to keep a spare card in stock. If the power supply or motherboard goes, I guess you're still buggered to a greater extent than you would be if a unit that only drove two or four channels failed, though.

[Steve Guttag]

Leo, There are 8-channel amplifier cards, not one per pair of channels. That is why the amplifier is available in 16, 24 or 32 channels...aways in a multiple of 8.

[Leo Enticknap]

Apologies. Did the training school in 2017 and only one field installation since, so memory is hazy.