SSL Duende

DSP powered plugins

SSL Duende DSP powered plugins

Review by George Shilling

Duende is a Spanish word – “A mysterious power that all may feel and no philosophy can explain.” But I’m going to try anyway… Duende comes as a 1U rackmount box which houses a board with 40-bit floating point DSP processing engine chips. Despite the manual talking of squeezing the processing into a 1U rack, there is mostly air inside: this could easily have fitted into a rather smaller package, but the smart 19” format means that most studios can screw it into the bottom of a rack and impress clients. The box is very light, and apart from the DC connector, the rear simply provides a pair of Firewire 400 connectors (which normally makes the PSU redundant). Accompanying the unit in the elegantly packaged box is software which installs the accompanying plugins onto your computer. These are Audio Unit and VST as standard, the latter wrapped into RTAS versions using a second installer. Included with the unit are Channel Strip and Bus Compressor plugins, optional add-ons currently comprise Drumstrip and X-EQ which demo for a short time unless purchased.

Installation is straightforward and quick. I suffered stuttering audio problems that SSL initially ascribed to buffer problems, and a reinstallation seemed to cure it. But when the problem returned, two reinstallations failed to cure it, and it turned out that chaining the box after a DVD writer on the Firewire buss was causing bandwidth choking. There was little indication in the manual that Duende needed to be first or have its own dedicated Firewire buss, but perhaps this should have been obvious.

On a Mac the control panel is installed to the Other section of System Preferences. There is nothing to control here, but the page that appears displays DSP slot usage (there are eight slots across four chips), along with driver and firmware versions, and serial number. One Duende allows 32 mono or 16 stereo plugins at up to 48kHz - the four different plugins each use one of the 32 memory slots available. Numbers are halved for 88.2/96kHz operation. As with other wrapped/powered plugins, these still seem to use some of the host computer’s horsepower, although Duende is slightly less taxing than the UAD-1 PCI card, for example.

SSL Duende DSP powered plugins

The Channel Strip looks rather familiar, and is based on the EQ and Dynamics section of the C200 digital console, which was itself modelled on analogue SSL desks. EQ can be switched between E-Series and G-Series style. +/-20dB Gain knobs are provided on input and output, both accompanied by level metering. The Input has a polarity flip, and the output a Sidechain Listen button. Just like on a K Series, the Filters can be switched to the Dynamics sidechain, or moved to the first point in the chain (instead of after the EQ). The four band EQ is smoother and cleaner than the Waves SSL 4000 collection version – there is no modelling here of analogue distortion, but it sounds silkier than I recall the Waves version, even with the latter’s Analogue emulation disabled.

Watch our video interview with SSL's product manager talking about Duende

Nevertheless, it has a very powerful analogue feel to it, just slightly smoother and sweeter than using an analogue SSL. There is an obvious difference between the E and G modes as expected; the technical differences are well documented, suffice to say that the G is glassier while the E is more ‘rock and roll’! The Dynamics section is excellent and familiar to SSL console users, switchable Pre-EQ (there is a useful signal flow display at the bottom). Both the Compressor and Expander/Gate work just like the original desk sections, with similar LED indications of gain reduction. It’s all thoroughly convincing; no doubt more ‘digital’ sounding than a 4000E/G, but powerful and super sounding processing for any kind of music.

SSL Duende DSP powered plugins

The Buss Compressor is another familiar looking design, with a lineage going back to the famous Quad Compressor of 4000 Series desks. For sure, there are subtler compressors available, and it may be mainly down to the fact that these were built into desks that they became such a popular tool. But for whatever reason, the SSL Buss Compressor is a familiar and enjoyable sound across a mix. With a mono version also provided, one can try this across anything. The Auto Mode sounds particularly good for drums. Auto is the safest mode for the mix buss, otherwise things can get a bit rubbery or start pumping. Initially I wasn’t sure that this sounded quite as instantly gratifying as one built into a big analogue desk, and the enormous meter’s needle looked rather flickery, but set up carefully it did the business, gluing the mix together as promised and adding a bit of excitement. All the familiar controls are present, however, the designers missed the trick of Waves’ version which has the AutoFade function bolted on.

Drumstrip is the first available add-on plugin for Duende. It comprises an interesting combination of five processor blocks, each with individual bypass. The processing order can easily be changed at will using the display at the bottom. Adjacent Peak and RMS metering is provided for both input and output, and there is also an unusual “Dynamic History Meter” which displays the dynamic range covered over the last second or so. A Gate provides separate Open and Close thresholds, and Attack can be set super-fast. It works really well, with no nasty clicking, but lacks sidechain EQ or external keying. The Transient Shaper is similar to the SPL Transient Designer hardware box. No-one seems to have made a plugin quite as good as that hardware, but SSL have made a brave attempt here.

An unusual innovation is the Audition mode which enables the Amount to be set to catch the peaks required. Plus there is a Speed knob to set the transient decay, and a Gain control to send the required amount of signal to the detector. It does sound really good, adding some nice crunch in ‘Inv’ mode (to soften the transients and add body) but despite all these extra knobs, as with Sonnox’s fiddly Transient Modulator the range seems not quite as extensive as the SPL, although there’s usually plenty enough here to work with.

Separate HF and LF Enhancers are provided, along the lines of Aphex Aural Exciter and Big Bottom processing. These are extremely powerful and surprisingly good, bringing some bottom end to signals which start out with virtually none, and adding strong HF to dull signals, or just a little extra sparkle as required. These use Drive and Amount knobs, plus a Frequency knob for the HF and a Turnover frequency knob for the LF processor which acts downwards from the selected frequency. Also included is the simple but fabulous Listen Mic Compressor which was available as a VST as the LMC-1, but now featuring a Wet/Dry knob and an EQ In button. It sounds wonderful across a drum buss – for a subtler effect one can blend with the wet/dry knob, or crank it for the full-on Phil Collins. The EQ In/Out allows a choice of full-range audio or the slightly telephoney character of the listen mic circuit.

X-EQ is the second add-on plugin, a ten-band EQ with a comprehensive selection of variable filter types and bell shapes, developed in collaboration with DSP software house Algorithmix. Its graphic appearance is similar to PSP Neon, but X-EQ lacks the linear phase processing of that particular plugin, taking a more conventional approach, albeit with some of its own unusual and unique features. With this plugin SSL have introduced a proprietary file management system for presets. So confusingly there are three ways to load and save presets in Pro Tools: using Pro Tools’ settings bar at the top, using the VST bar at the bottom, or the SSL Load and Save just above that! However, the SSL system ensures cross-platform compatibility, and this is the only Duende plugin to come with a library of settings, claimed to be based on settings used by “top mixing engineers’. This is perhaps slightly silly, as surely one adjusts EQ by using one’s ears or even meters, rather than by dialling up presets. As with most good plugin EQs there is a graph with draggable nodes for each band, along with mouse-controlled adjusters and direct numerical entry of values. However, the graph dragging was less than smooth on my system, making small adjustments tricky.

There are High and Low Pass filters with 6-48dB/octave slopes (in 6dB steps) and five different filter types including Butterworth, Gaussian and Bessel. 20dB boost and cut is available for the High and Low Shelf bands, which use the Q control to set overshoot/undershoot. No less than nine different bell curves are available for the six parametric bands in Serial mode, with various different constant and proportional Q, symmetrical and asymmetrical settings. Parallel mode works like a traditional passive EQ and the sonic signature is noticeably different, remarkably clean and thoroughly enjoyable, particularly for mastering applications. Helpfully, A and B settings slots allow quick comparisons, whilst an FFT Spectrum Analyser can be superimposed on the display, enabling easy spotting of problem frequencies. Linear EQ aside, this really has to be just about the most comprehensive EQ plugin available, and it would surely take months or years to really get to know the sonic implications of all the different curves and modes.

With all the plugins there was a problem with the Pro Tools auto delay compensation: when one hit the host’s Bypass, everything went audibly out-of-wack. There is a Bypass within each plugin, which works fine as long as you know to use it, but it’s a nuisance having to either open the window to bypass, or make the plug inactive. There was no such problem with Logic’s PDC, and SSL say this will be addressed. But apart from such teething troubles, the Duende provides a great source of mix processing. Channel Strip and Buss Compressor provide excellent bread and butter SSL processing, while Drumstrip and X-EQ both push into unique territory. It’s all very good, and I suspect there is yet more to come.

Pros: Traditional and modern SSL processing; Extra processing horsepower

Cons: Uses some host CPU power; ADC problem in bypass; Too much latency to track with; Unnecessarily large box!

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