BASICS AND INSTALLATION

Duende, a 1U rack unit, contains four 333MHz DSP 40-bit floating point chips. Each has eight “virtual slots;” you can run one mono plug-in per slot at 44.1/48kHz, for 32 plug-ins total. Duende supports 88.2/96kHz, but this halves the plug-in count. Stereo instances use twice the DSP resources of mono instances.

Duende connects to the host via a FireWire cable (ideally, it would get its own port, if not interface), and there’s a second port for daisy-chaining other devices. Duende can be bus-powered or use the included universal power adapter, which has a nifty “pop in the correct plug for your country and electrical system” design.

Software installation is easy. VST and AU support is native; if you’re a Pro Tools user, you can also install a light version of FXpansion’s excellent VST to RTAS adapter/wrapper. As I already had the full version of the wrapper on my computer, I was concerned about how the installer would handle that — but the SSL plug-ins just installed into my existing version. The installer even includes a built-in firmware updater for the hardware.

Like most DSP products, Duende runs only plug-ins that have been coded for it. Currently, only two come with the basic Duende package: Channel Strip and Bus Compressor. These are based on the algorithms from the high-end SSL C-200 digital console, which was itself modeled after SSL’s own analog consoles like the XL9000K. While they’re not identical to the C-200 algorithms (according to SSL, they’re refined for Duende), with a lineage like that, Duende certainly looks promising.

APPLYING THE PLUG-INS

The SSL Channel Strip plug-in (Figure 1) replicates the controls on an SSL hardware console and offers multiple functions, including high and low pass input filters, a four-band EQ with two fully parametric midbands and sweepable high and low frequency bands (switchable to either shelving or fixed Q bell curves). The EQ can respond like the original E Series SSL EQ or the later model G Series desks. Having a choice of EQ options is a plus, as each has its own sonic character. While I couldn’t do an SSL console/Duende shootout due to time constraints, both EQ options sounded wonderful to my ears, and neither EQ type requires huge amounts of boost or cut to hear changes — which I consider a hallmark of a really good software EQ. Furthermore, there’s a dynamics section (compressor and gate/expander), good multi-segment LED-style metering for input/output levels, and also separate compression and expansion meters.

The compressor has variable threshold, release and ratio knobs, as well as auto or 1ms fixed attack time options. The auto attack setting lets a little bit of the initial note attack pass through relatively unaffected, which is generally how I want a compressor to function, although the fast attack option can be handy for clamping down hard on the entire signal. The compressor also offers a switch-selectable choice between the standard soft knee RMS (gentle) mode or hard knee Peak (aggressive) mode.

The Channel Strip’s Gate/Expander also lacks a dedicated attack control, although you can switch between the normal attack default of 1.5ms and a fast attack setting, which hits full attenuation in 0.1ms. A range knob offers up to 40dB of attenuation; there are variable threshold, release, and hold time knobs, and an “Exp” button for selecting expansion instead of gating. The expander has a fixed ratio of 1:2, and works very well for reducing noises like amp hiss that might otherwise be audible when a guitarist pauses between notes. You can enable EQ and dynamics independently, and the dynamics section can go pre- or-post-EQ. Sidechain capabilities are also available, so you can use the EQ and its independently-switchable filters for frequency-specific dynamics triggering. This powerful plug-in has become my “go to” channel strip plug-in for mixing.

Many engineers consider the SSL bus compressor ideal for “gluing” tracks together in a mix, and this plug-in can do exactly that. The interface (Figure 2) is simpler than the channel strip, with a large VU-style gain reduction meter and only two continuously variable controls: threshold and makeup gain. Like the hardware console, the knobs offer predefined values (2:1, 4:1 or 20:1 compression ratios, 0.1, 0.3, 1, 3, 10, and 30ms for attack time, and 0.1, 0.3, 0.6, 1.2 second, and “Auto” release time settings). I found this plug-in’s auto release as well-behaved as the Channel Strip dynamics section’s auto attack, and it generally tames the source material’s dynamics in a very musical way. But again, I would have liked to have seen a 50ms release time setting for when I wanted a really fast compressor release, along with a variable attack control.

I’m sure a lot of people will just strap the Bus Compressor across their stereo mix bus, but it also works well on individual tracks, and I particularly liked it on bass and vocals. If you normally run “stems” or stereo submixes out of your DAW system into an analog or digital mixing board, try placing a Bus Compressor plug-in on each stereo output bus — with a little listening and careful adjustment it’s very easy to get the tracks to gel into a cohesive mix instead of overly separated individual elements.

CONCLUSIONS

Latency is an issue with any outboard DSP solution. It takes time for your computer to route the information into the processor, perform various calculations, and spit data back out again. Thus Duende, like similar products, is intended more for mixing than tracking, as it introduces delay on any track with an SSL plug-in inserted. On my Athlon 64 4200 dual core PC, delays ranged from 448 samples with the Bus Compressor running at Pro Tools LE’s 64 sample hardware buffer setting, up to 2,436 samples for a Channel Strip plug-in when using a 1,024 sample hardware buffer setting. As PTLE does not compensate for these delays, it is necessary to compensate manually by either nudging unprocessed tracks back on the timeline, or using Digi’s Time Adjuster plug-in to delay any unprocessed channels. However, it’s worth pointing out that Pro Tools LE is the exception when it comes to handling plug-in latency; most other host applications, including Pro Tools HD, offer full latency compensation.

Although delays occur with all external FireWire DSP products, it’s odd (and with Pro Tools LE, complicates the compensation process) that the two different plug-ins showed ever so slightly different delay amounts. For example, on a 24-bit, 44.1kHz session, regardless of the Pro Tools hardware buffer setting or whether tracks were stereo or mono, the Channel Strip showed exactly 4 samples more delay than the Bus Compressor at the same hardware buffer setting. It’s not a big deal in actual use, but worth noting.

I really don’t have many complaints — and none when it comes to the sonics. I’d like to be able to type in control values directly; adjustments can be made only via the onscreen knobs (although you do get a “mouseover” numerical value above all of the continuously variable knobs). Since I like really fast compression release times for some tasks, I wish the Channel Strip compressor offered release time options in the sub-100ms range, and the Bus Compressor had a variable attack control and faster release options. But the range is modeled on the SSL hardware units, and stays true to them in that respect.

Latency concerns exist with any outboard DSP product, so I can’t fault SSL for not defying the laws of physics. Finally, while I wish there were more plug-ins available, SSL is a console company. Duende’s plug-ins replicate the functions of their mixing consoles — which is the safe play for them, because really, that’s what the market wants and that’s their forte. Hopefully, they’ll eventually offer other plug-ins; at the Winter 2007 NAMM show, SSL announced an optional add-on plug-in called Drum Strip, so matters look encouraging in that regard.

As an enhancement tool for a native DAW, Duende’s powerful DSP capabilities and sound quality give your computer a serious boost. The two plug-in types are extremely high quality, and even if you find native plug-ins that can keep up sonically, chances are they’re going to be CPU hogs. By offloading those tasks to the Duende’s DSP, your host is freed up to handle other CPU-intensive tasks, such as convolution reverbs.

So is it a winner? For under $1.9k, 32 channels of SSL-quality DSP-based plug-ins for your DAW is certainly a price breakthrough, and the sonic quality is as good as, if not better, than anything else I’ve ever heard in software. I definitely recommend checking out Duende, but you’ll have to find your own — I’m purchasing the review unit.