Mixing on the Akai DPS24 Using Realtime Plugin Effects

ill o.g.
Battle Points: 3
Even with the continued popularity and increasing system power of standalone hardware DAWs such as the Akai DPS24, recordists are still always on the hunt for "more." More flexibility, more power and the ability to "go outside the box." It's clear that a big part of accommodating users in this regard is for manufacturers to implement standards that are as ubiquitous as possible. The ADAT interface standard certainly fills that role nicely. There are many manufacturers of both hardware and software that support the standard for passing audio data between platforms, and the list seems to still be growing. One such piece is the Akai DPS24, a 24-track mixer/recorder that includes eight channels of ADAT in/out from the factory. As an added benefit, that spec is upgradeable via an expansion card to a full 24 channels of ADAT in/out. The system provides extensive routing options for sending channels (inputs, tracks, fx, auxes, etc.) via ADAT using a simple patch screen. Returning ADAT signals can be routed to inputs or disc tracks (either for recording directly or arming and using as additional input channels during mixdown) and all at full 24-bit resolution.

Not long ago, we were discussing the possibilities presented by so much connectivity and their implications specifically during mixing. An obvious scenario that seemed awfully enticing would be the ability to send out and process disc tracks and return the processed tracks for summing along with onboard tracks during a mix in realtime. Some quick testing using a software DAW provided astonishing results. By arming some tracks, routing ADAT sends from the DPS24 to those tracks, applying plugin fx and returning those signals to the DPS24's inputs (where they were further routed to the L/R master bus for mixing), it was immediately apparent that the setup had very large possibilities indeed. This encouraged us to dig deeper and see what the limitations were. While the concept isn't new, the whole process seems to get very little attention from users of machines like the DPS24. This may be partly due to the fact that as good as all these machines are, multichannel in/out via a "standard" interface (especially one that's included with the machine) is oddly rare.

Since both John Geib and myself own DPS24s, we were able to try testing the system's limits immediately using eight channels of ADAT send and return to a connected PC configured as an fx loop. We both have pretty "current" PCs with ADAT soundcards installed (one being a Steinberg VSL2020 and the other an RME Hammerfall 9656), but immediately realized that the key to putting together a package that would be attractive to users of the DPS24 would be to find software that would host fx plugins and that would permit monitoring them in realtime, without breaking the bank. While there are several we found, one that really fit the bill nicely is called "Console Sound Modular Studio" or simply "Console." This is an inexpensive shareware program ($54) from a Japanese developer named Art Teknica that has all we were looking for -- and much more.

Console, in addition to being able to receive, monitor and send out digital audio in realtime, can also host VST and DX plugins, as well as those in the VSTi and Dxi formats. The graphic interface is clear and simple, setup is a breeze, and as many channels of in and out as you have on your soundcard are available. In addition, there are included with the package some very useful plugin modules (mixers, channel converters, even a plugin version of Console for running it under another host application where you could use its ability to run both VST and DX plugins as a "wrapper" for applications that don't support one of those formats. In addition, there is MIDI capability that allows for both the remote control of plugin parameters as well as automation of those parameters if the connected DAW can send MIDI CC#s from automated mixer channels. That's a lot of value for a package that costs less than $60. Obviously the cost is a large consideration for people who have spent good money on a non-computer recording solution, but the simplicity is as well. Many users of hardware DAWs choose them because of the "hands-on" nature of their control surfaces as opposed to the sometimes confusing interfaces of some of the more powerful computer DAWs. Given the fact that a good percentage of people who run hardware DAWs also have a computer either in or nearby their studios, we assumed also that the possibility of using a piece of gear they may already have to provide a powerful way to expand their recorders would be an attractive option. It should be noted that the general concepts described here are applicable to machines made by Yamaha, Korg, Roland, Tascam, etc., to varying degrees. While even analog send/returns will work well, they will be affected by a small increase in latency. Whatever the platform, it's best to keep the whole process in the digital domain to keep latency to a minimum.

Getting it Working

Since both John Geib and I have the ADAT expansion cards in our DPS24s, we can send out for processing as many channels as we have tracks.handy. The connections are simple. We run optical cables from the ADAT outs of the DPS24 to the ADAT ins of our computer soundcard's and optical cables from the ADAT outs of our computer soundcard to the ADAT ins of the DPS24. A total of six slim cables to carry 48 channels of digital audio (24 in each direction), less "spaghetti" behind the gear.

On the DPS24, we created and saved a custom routing patch whereby all 24 tracks are assigned to separate (24) ADAT channels and the returning ADAT signals from the PC are routed to input channels. It's also noteworthy to mention at this point that the returning signals can easily be handled by a simple stereo pair of inputs since they'll only be summed with any other signals present for mixing. However, it may be desirable under some circumstances to keep some of the returns separate and route them to their own stereo pairs. Also, the DPS24 can utilize unused disc tracks as spare input channels by simply arming them and routing the incoming ADAT signals to them. By default, disc tracks are assigned to the L/R master bus as you would expect so that's all that's needed. On the computer side of things, one of the obvious limitations will be absolute system power. The bigger and badder the computer, the more processing it will be capable of. We found out to our surprise, though, that even a fairly modest computer by today's standards will run up to eight or more plugs realtime. Console also provides a CPU monitoring function, so the user can see how much system power a given plug is using. This information can be very helpful in deciding what plugins to use in a given project. For sure, there are some plugins that just won't run in realtime, but there are a great many plugins that not only do run under this scenario.but sound wonderful, and many use very little processing power ("CPU"). To make things even better, many free plugs work exceedingly well and sound great. Go figure!?

Using the Hammerfall 9656 under ASIO, I can run a full 24 channels (which could be a direct track send from every track) and process them in as many plugs running a P4 at 2.8 with only 512 megs of RAM. There is the ability to route, combine or separate all of these signals from the single screen work area in Console. All the plugs can be individually opened to set up or change their individual parameters also. And since these connections and settings can get as complex as necessary, Console projects can be saved for later recall. Open a project in the DPS24, open the corresponding project in Console and you're back at work.

Possibilities


Using the concept of an fx loop as the example for comparison, there are two basic ways to use all this. First as a "send/return" type setup, you would want the ability to mix processed sound with the original unprocessed signals. In this case, sends from the DPS24 are processed in Console where the "mix" parameter of the plugin(s) is set to 100% or full-"wet." They are then returned to spare input channels (and/or spare tracks as described earlier) where they can be summed with their sources along with any other signals present. The individual input faders act as the "fx returns," and these can (of course) also be automated. As an "insert" type effect (such as compression or eq), the same applies except that the original or source signal is deassigned from the L/R master bus so that only the returning processed signal will be heard. As a way of maximizing potential, you can also group signals before they leave the DPS24 by assigning them to a group bus and then designating that group as an ADAT send. You can also designate either fx or aux sends as ADAT send channels so that like tracks can be processed in one shot. If you had six tracks of background vocals, it would be a simple matter to group those signals before they left the machine to be processed in one shot. By doing this and choosing specific plugs carefully, even a modest computer's capabilities can be maximized. Also, by running a sequencer and some VST or DX instruments.you could simultaneously add and process instrument tracks to a mix running realtime. The possibilities seem as varied as the imaginations of the users. There is a small amount of latency to contend with, but it's all but imperceptible using the right plugins and properly configuring your soundcard, specifically the buffer settings. Using "ambient" or "time-based" fx like reverb, chorus, delay etc., the latency is inaudible. Many dynamics and EQ processors will also run extremely well under this scenario. The ones that are designed to look-ahead into the audio stream will generally not work well.or at all. When using track direct outs as sends, all the DPS24's onboard fx channels are still available in addition to what you're doing with Console. That ought to be enough simultaneous processing power for even a real "fx-hog"!

It also should be mentioned that the computer realtime processing we're dealing with here is not just applicable for mixing. You can just as easily process an input during tracking. Even though the DPS24 provides many options for setting up separate cue mixes for the talent and monitoring, Console expands those options as well. By adding some additional hardware.you could set up some extremely complex simultaneous mixes completely independent of the several that you can set up from within the DPS24.

Finally, we were also concerned about sound. What good would all this be if the returning signals were even slightly degraded with respect to their original source signals? This would be especially problematic for tracks where you would only be using the return or "processed" signal in your mix as would be the case with a pseudo "insert" effect. The good news is that our decidedly non-scientific testing proves this to be a non-issue. Also, the mix bus on the DPS24 seems to have plenty of headroom. Mix away!

Conclusion

This whole thing works so well, it's hard to understand why more people don't seem to be using it. Again, we understand that we really haven't broken any new ground here but are just passing along what we consider to be very useful information. It could be that, in many cases, people just assume that this won't work and therefore don't try it. The amazing thing about all this is that many can try it out with a combination of hardware and software they may already have, not to mention some software that's available for free, or very little cost. Even with "just" the eight-channel ADAT in and out that comes standard with the DPS24 and a relatively inexpensive soundcard that can handle at least those eight channels, you can add a huge amount of processing power to your setup. Users of other machines can and should experiment with what's available (either analog or digital) for your machine to send and return signals to the computer to do this kind of processing. You very well may be pleasantly surprised. This truly seems to be a winning combination. People who are attracted to hardware DAWs like the DPS24 because of its tactile nature, immediacy and pre-integration needn't feel that they're sacrificing some amount of flexibility and expansion. It's simple, powerful, cost-effective and waiting for you to try.

(By John Havlicek and John Geib)
 

bhunt

ILLIEN
ill o.g.
This was very intresting to look at the DPS like this. Using a computer and instead of having lots of outboard, just use a CPU as a effects rack can be beautiful.
 
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