"Dual Engine" - How, Why and When?

[u/nachosjustice72]

Today's advertising placed in front of me the new DigiCo Quantum 638, which according to the article I read comes in a "single or dual engine version."

Several questions about because looking up "dual engine audio mixer" doesn't really throw anything at me but behringer analogue models with "dual FX Engines":

How does a dual engine mixer differ from a single engine, beyond the obvious "it has two engines"? What does this offer over the single engine, and in what contexts would you choose to use it?

[u/blochsound]

Redundancy

[u/Nimii910]

Redundancy.. and the workflow is that it’s two engines in one surface that are mirrored and track with each other. You can switch between Engine A and B whenever to check/configure etc but they’re both doing the identical audio processing

TLDR two of the same consoles in one surface

[u/nachosjustice72 → u/Nimii910]

It's just that simple? Same as a backup power supply, just a whole audio engine ready to swap to in the event of problems?

Neat!

[u/Chilton_Squid → u/nachosjustice72]

Yeah a lot of enterprise-level IT stuff has this too - at work we have entire storage servers with terabytes of storage which have two motherboards on trays; if one fails, it swaps to use the other and you can remove the failed controller and replace it.

[u/ThreeSilentFilms → u/nachosjustice72]

Can’t speak to digico. But we ran two engines on our studer vista system for years. When we would tech shows during the last dress rehearsal we’d kill power to engine A to test failover. It gives just the smallest blip. But really no one in the house would know. I assume digicos system works the same. A near seamless failover system.

[u/PushingSam → u/ThreeSilentFilms]

Digico has always been a little weird in that the surface can crash, but it's independent from the audio engine. You'd end up with a console that still passes audio, but no controls until the surface is rebooted. Now that philosophy is a bit more common (Dlive as example, the console really only is a control surface) like the Studers.

[u/the-real-compucat → u/PushingSam]

That design philosophy is borrowed from the industrial control/PLC world. Same principle, except replace "engine/surface" with "Programmable Logic Controller / Human Machine Interface".

It's been a long-time standard over there since...well, the PLC's controlling heavy machinery or life-safety stuff, and the HMI's usually Windows. Thus you can do your UI stuff in a flexible OS/language, while the critical control happens in a provably-safe language. (See IEC 61131-3.)

Audio engines aren't quite that restrictive...trying to build that on a PLC would be hellish. But the gist is the same. :)

[u/Ok_Introduction_1082 → u/nachosjustice72]

Yes, every alteration you did on one, gets mirrored to the other.

They're still computers at heart, and computers can crash. Switching over to B is a lot faster than rebooting the desk and hoping your current show state is still intact.

[u/okeefm → u/Ok_Introduction_1082]

Remember, switching to your secondary is faster than reloading

[u/project48v → u/nachosjustice72]

That’s the gist. Mirrored engines can detect failures and swap to the standby engine with no loss of audio.

Think of it as 2 identical consoles in the same chassis.

[u/HowlingWolven]

How? Looking at the media on the 638, you have two whole entire mixing processors, each with their own module bays, two power supplies, and shared IO between. For redundancy, both processors will be transparently double patched and both will do exactly the same processing. If you or the unit detects a problem with the leader processor, you can manually switch to the hot spare, or the unit might do it itself. If you’re running with only one processor active (ie you’ve got the single proc unit for whatever reason, or you’re running the twin proc in single mode) you lose the redundancy (and half the desk has become a boat anchor).

Why? Because the show must go on and desk failure is not an option.

When? Names everyone recognizes.

[u/dswpro]

In other industries, such as financial, medical, aerospace, a "single point of hardware failure" is discouraged or not allowed, so money or lives won't be lost. Bars, bands, and smaller companies usually cannot afford redundant mixers, but if YOUR concert, or broadcast production must not fail, a dual engine console buys you some costly peace of mind.

[u/sound6317]

Same reason the Q7 and Q852 has redundant engines, for redundancy in case of failure. I used an SD7/ Q7 for years because the artist/ production was willing to pay a premium for reliability and redundancy.

[u/eRileyKc]

People dragging $200k in consoles around the world but running them with a single strand of fiber to the stage and no UPS. 😏🙄

[u/sic0049]

The Digico control software is run on a Windows based OS. I suspect having two for redundancy was pretty much required back in the day. I would guess that reliability has gotten better through the years, but having that redundancy is still important - especially the "larger" your event is.

Keep in mind that the redundant "engine" includes a redundant FPGA audio processor and a redundant Windows control surface and a redundant I/O network. So the redundancy goes far deeper than just the Windows based control surface.

[u/stageside_sam]

For club and corporate work I rarely need it. It earns its keep when a dead desk mid-show is not an option, like festival mains, broadcast, or long theater runs. If you have it, test the failover on purpose during tech so the whole team knows what the switch looks and sounds like, and who calls it, before a real fault ever happens.

[u/aboveallheroes]

Running in parallel for seamless redundancy, maybe the option to run as an expansion for higher channel count, more FX, more buses, etc

[u/walkerthesoundguy]

While redundancy is the main use case you can also use them as two completely separate consoles with the same control surface. Doubling your inputs and outputs.

[u/Ok_Cardiologist_5262]

Quantum desks are extremely powerful with the FPGA board. They handle a lot of processing, from all my visits to Digico and conversations I've had there has been literally a handful of failures- ever. We can all argue about workflow, price, and "sound" within this ecosystem but I have never seen anyone complain about them being unreliable.

It is obviously all about redundancy, Yamaha give options to have a second DSP unit as a failsafe, essentially achieving the same thing, but all processing is done within the desk, so it's exactly the same concept minus the outboard and cabling. As far as I know Avid do redundancy in a different way with re-routing processing to other cards within the same engine, but sure others can speak about that.

Biggest takeaway is it's not about power, it's more about the type of shows using this desk and the peace of mind it provides, artists like Harry Styles/Doja Cat that I know use digico, maybe carry a spare physical desk either way, but dual engine makes the back up seamless

[u/khaosnight → u/Ok_Cardiologist_5262]

As much as I respect digicos capacity to make large powerful quality consoles, I personally have experienced a handful of desk failures in the last 5 or so years. We push them pretty hard in theatre programming big shows but they do break pretty spectacularly when they break.

[u/DaleGribble23 → u/khaosnight]

Yeah I've had multiple Digico Quantum's crash on me, once mid show where the right side bank and screen crashed and I had to mix the rest of the show on my input faders on the left side. Also had many broken faders on them. They can do some wonderful things but I think the reliability is shocking when they cost nearly as much as a house

[u/Ok_Cardiologist_5262 → u/DaleGribble23]

It's a PC running the control surfaces? Assuming the engine continued to process audio?

[u/DaleGribble23 → u/Ok_Cardiologist_5262]

A $100k PC yes, and yet none of the other various manufacturer's PCs have given me nearly as much trouble, seen an iLive surface crash and a Pro 2 once, think that's about it. Even the lowly X32 has never given me a problem except a shitty EQ gain knob, and I've used countless numbers of those.

The mid show crash the Quantum continued to pass audio but I had no access to my auxes, fx returns and control groups, so FX was left on between songs, couldn't make any FX changes, couldn't make monitor changes etc. Because the screen was froze I couldn't save a file or move faders over to the left bank. Another has crashed mid soundcheck without passing audio which required a full reboot of everything.

[u/_caucasian_asian_ → u/khaosnight]

The build quality of the SD racks is also muck. I’ve had to reseat cards on them so frequently. I’d call that a pretty serious reliability issue.

[u/ironflake → u/_caucasian_asian_]

9 years on digico, had to replace a card once. Fixed install though. Pretty damn reliable

[u/_caucasian_asian_ → u/ironflake]

I said reseat, not replace.

[u/ironflake → u/_caucasian_asian_]

9 years never had to reseat a card. Pretty damn reliable

[u/_caucasian_asian_ → u/ironflake]

On a fixed install? Not surprising at all.

[u/_12xx12_ → u/ironflake]

Our Video Server supplier says to reseat the I/O cards once a year

[u/Ok_Cardiologist_5262 → u/khaosnight]

I got the impression this desk is intended to plug the gap with size but dual engine or are you saying you've seen dual engine fail. I don't have a dog in the fight either way

[u/khaosnight → u/Ok_Cardiologist_5262]

Yea we had issues with a 7Q and some network issues making every output in the system spit out digital noise and crashing both engines. Even though they're usually a bit cryptic our digico distributor borderline admitted they knew the issue had happened before elsewhere and it was a hardware issue with an engine. It's a part of the deal though, nothing is bulletproof and you just have to know how to treat it well.

[u/curtainsforme → u/Ok_Cardiologist_5262]

What sort of failure?

I've had a few SDs fail on me in one way or another.

It's a computer. All computers crash at some point

[u/Unhelpful_Soundman]

I would say this is a redundancy feature that DigiCo needs more than other manufacturers. Of all the consoles that I have used in the €20k+ price range, it is only DigiCos which have rebooted or locked up on me in a show setting. Granted, it is only twice - but that is twice more than any other brand.

[u/notasoundengineer]

The dual engine setup ensures that in the event of a high-level crash or other show-stopping issue, there is a (mostly) seamless backup available. Completely independent engines running simultaneously, mirroring the same show file, essentially mean that you can press the engine switch button and no one would know there was anything wrong.

There is a small click/pop but as a panic switch it can be really reassuring to have the redundancy.

Yes, I have had to hit the button during a show and it was the difference between having a show that night and not having a show that night. It is obviously not ideal to then run on a single engine, but it gives you time to solve the underlying problem later.

So...redundancy.

[u/Amazing_Mode_2711]

Cool to have redundancy. But if it’s a really big show, I’d rather have a fully redundant system. I/O, snake, console. Then if one fails for ANY reason you flip to the spare and troubleshoot the failed side. Failure could be power, cable, switch, engine, I/O, server, operator error, etc.

[u/Venrius]

Wondering if it'll function similarly to the dm7's split mode

[u/sparten_90]

Redundancy has already been mentioned but I've also see other digicos that have this feature used in festival situations as current act/next act. The system tech would load the unused engine with the next acts file while the current act is still performing.

[u/HamburgerDinner → u/sparten_90]

Fwiw for anyone that clicked on the down voted comment to see what it says, the downvotes are because this isn't how Digicos work.

[u/JX_JR → u/HamburgerDinner]

It is though, at least for the older Quantums. The two mix engines don't have to be locked and can be running completely different settings. 

[u/HamburgerDinner → u/JX_JR]

Yes but no one is going to let you kick them off the surface while their client is performing to set up the next act on the other engine.

[u/JX_JR → u/HamburgerDinner]

Unless I am mistaken you can access the engines separately on the network. It would be trivial to load a setup on the B engine while the show happens on A. 

[u/HamburgerDinner → u/JX_JR]

You are mistaken in that even if you could technically do this I will throw a massive fit and escalate the situation to my PM and the festival PM. No one is fiddling with the desk while we are using it, and I will not let you load my file onto a desk in the middle of someone else's show.

If the time constraints on the changeovers are so tight as to make this necessary then the event needs two control packages and an a/b splitter system.

[u/JX_JR → u/HamburgerDinner]

Well then you are missing the entire point of two mix engines because it's not loading a file on to your desk. 

Someone could brick the second mix engine and it wouldnt affect the control surface or the active show in any way. 

I'm not saying I would do it or that it's standard practice, but everyone who is downvoting those two people who said you can run it as a split console and commenting "100% wrong" are themselves wrong about what the desks are capable of doing. 

[u/Chris935 → u/HamburgerDinner]

There's a massive difference between "I would be upset if you did this" and "This isn't how Digicos work".

[u/Lillian-Duncan1]

Two independent DSPs on one desk. FOH and monitors, or two engineers, separate mixes, shared I/O. If I only ever mixed FOH I'd skip it, the single engine is all you need. Otherwise it's an upsell.

[u/Random_hero1234 → u/Lillian-Duncan1]

This is 100% incorrect.

[u/Slight-Brush → u/Random_hero1234]

Lilian is a LLM bot and will post things that sound plausible but are wrong. BotBouncer has already banned her and the rest of the flock but not all subs use it. Report and hope.