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Wizoo W2

Reverb Plug-in [Mac/PC] By Paul White
Published February 2006

Wizoo W2

With W2, Wizoo's aim is to combine the realism of convolution reverb with the flexibility of an algorithmic design.

As any reverb connoisseur will tell you, convolution or 'sampling' reverbs offer the most accurate recreation of real acoustic spaces, but sometimes a more old-fashioned artificial reverb is what sounds best. Though many companies have come up with clever processing to enable IR reverbs to be edited to a useful degree, the greatest flexibility of editing still rests with synthetic or algorithmic reverbs. Wizoo have clearly set out to provide the best of both worlds, because in addition to giving the user a choice of convolution or synthetic reverb, they have also made it possible to combine the two types in a very flexible way. As shipped, Wizooverb W2 comes with 15 HDIR (High Definition Impulse Response) models based on impulse measurements taken in a variety of real spaces, but these are backed up by an 'AIR' algorithmic reverb.

Wizoo's HDIR sampling process captures the sonic signature of a real space using mics, speakers and test signals, after which a proprietary process is used to generate metadata, which is used to maximise sound quality when the reverb is being edited. This is a key feature, as without some kind of intelligent processing, the changes that can be made to an IR-based reverb are quite limited.

On the synthetic side, the AIR algorithm is apparently not based on the conventional combination of delay and all-pass filter circuits used in most hardware reverb processors, but is claimed to offer similar advantages at a reduced CPU load. As a very general rule, HDIR is the best choice when you need the material to sound as though it is being played in a real space, while AIR places a lighter load on the CPU and may be more artistically desirable in some cases. When some of the competition offers hundreds of impulse responses, having a library of 15 HDIRs may not seem like a lot, but W2 will load and optimise third-party impulse responses to extend your library, and Wizoo claim that their IR optimisation will make your imported impulse responses sound even better than in other convolution reverbs.

Pages & Patches

To find your way around this plug-in and to see what it can achieve, it's best to start by looking at the interface, which comprises a number of pages accessed by buttons. The Presets window, where reverb types are categorised in different folders, opens automatically when W2 is launched, and a preset consists of a complete reverb program comprising the HDIR model and all necessary parameters. At the bottom of the display are five parameter boxes with associated knobs, the functions of which change according to what page you're on; the larger knob in the centre usually controls the most important parameter. The user can assign any edit parameter to control knobs four and five, but knobs one, two and three have fixed assignments. This means that up to five reverb parameters can be accessed directly from the Presets page, though you can go into more depth in the Edit page.

One of W2's unique features is the ability to 'render' IR-based early reflections and tails to a synthesized equivalent for greater flexibility.One of W2's unique features is the ability to 'render' IR-based early reflections and tails to a synthesized equivalent for greater flexibility.A list of all the main operations appears at the right of the display, which is also where patches are saved and loaded. There are input and output level meters at the sides of the panel with level controls directly below. A Dry/Wet knob sets the reverb balance: like all reverbs, when W2 is used in an aux send loop, this should be set to 100 percent wet.

W2 's editing options are, according to Wizoo, designed to work in the same way as a listener's perceptions. Any reverb pattern comprises an early reflections portion, which carries a lot of the audible information about the room type, followed by a decay tail, which tells you how reflective the environment is. The main, and largely familiar reverb parameters include Pre-delay, which places a short delay before the reverb, Room Size, which alters the perceived room volume, and reverb Decay Time. In the Edit page you can select HDIR only, AIR only or HDIR plus AIR, where part of the HDIR decay is replaced using the AIR algorithm. Either type can be used for early reflections or the reverb tail, and AIR editing can be done in real time without waiting for the IR to recalculate. One of the most obvious applications for combined convolution and synthetic reverb is to use HDIR to generate those important early reflections, then add an AIR-generated tail; this will enable you to change the decay time over a very wide range without compromising the signature sound of the room.

The other editing pages include Early Reflections, Tail and EQ. In the first of these, Render ER is a function I haven't seen on any other reverb unit to date: this replaces the HDIR model's early reflections with an AIR synthesized version that matches the sound as closely as possible. Not only does this conserve CPU power but it also opens up new editing options, as AIR reverbs are always more editable than IR-based reverbs.

The reverb can be shaped using EQ.The reverb can be shaped using EQ.

The Tail menu tab allows you focus just on the reverb tail, with options including a Low Freq/High Freq split that lets you vary the relative decay times of its high and low-frequency components. Ambience is another unusual reverb parameter, more commonly being associated with a type of short room reverb; here, it lets you place the sound source further into the room. We're on more familiar ground with Density, which adjusts the density of the reflections making up the reverb tail, while Colour adjusts the timbre of the tail, making it brighter or darker. Where the reverb tail is IR-generated, you can also modify its envelope in natural and not-so-natural ways via the Envelope tab. Like the early reflections, the tail can be rendered and replaced with a synthesizer version. The EQ menu tab brings up a parametric four-band, post-reverb EQ with individually bypassable bands, which processes only the wet signal.

In all cases, the balance of the early reflections and the reverb tail can be changed, and you can also adjust the point where the early reflections stop and the tail starts, though this 'crossing' parameter is not available when combining IRs and decay tails as the system decides on an optimum crossing point for you, based on metadata stored with the IRs. It's also possible to reverse an entire HDIR reverb pattern to create an eerie 'backwards' sound, though this can't be applied to AIR reverbs.

Standing Alone

Unusually, W2 can be operated as a stand-alone application, which means that if you have a spare computer and I/O device, you can run it as a separate reverb unit, just as though it was a piece of hardware. Under Mac OS, the stand-alone version appears in the Applications folder and uses the selected Mac audio I/O. Both the plug-in version and the stand-alone version have identical facilities, as well as sharing the same impulse response library. The included IRs span a whole range of spaces from small ambiences and post-production environments, via the usual studios, rooms, halls and chambers to churches and cathedrals. There are some lovely rooms that sit somewhere between reverb and ambience, adding a nice sense of space without seeming cluttered. Post-production settings include a tunnel, an empty oil tank and even a stone cave, which is pretty handy in musical applications too. The ambience and room sections also include some excellent drum and vocal treatments, but if you're after a real retro drum sound, there's also a folder of non-linear reverbs for all those classic gated and reverse reverb effects. More flexibility is available by taking, for example, an ambience or room early reflections IR and then combining that with a longer reverb tail taken from another IR or AIR reverb setting. This can work particularly well on vocals.

Stereo And True Stereo

W2 is a true-stereo reverb where HDIR IRs are available in both Stereo and True Stereo versions; in standard Stereo mode, the listener perceives the sound as though it is coming from centre stage, as it the case for most reverb units. By contrast, True Stereo mode enables the listener to localise the position of the source, but this requires two stereo IR computations and so doubles the CPU loading. Note that in True Stereo mode, the left and right channels work independently, so a signal fed into the left input will only generate reverb at the left output.

Reverb tails generated from an impulse response can be modified using the Envelope tab.Reverb tails generated from an impulse response can be modified using the Envelope tab.In both modes you can adjust the input signal's stereo spread before it hits the reverb engine, and interestingly, this control affects not just the stereo width of the reverb but also the apparent distance of the sound source from the listener, with lower values equating to larger perceived distances and vice versa. There's a further control in the Output section to adjust the reverb's stereo spread.

With HDIR and IR reverbs, there's the facility to adjust Directivity, which is a way of shaving off the first few milliseconds of the impulse response to avoid excessive coloration when combining the reverb with the dry sound. This shouldn't be confused with pre-delay, which is a straightforward delay before the reverb kicks in.

Third-party IRs can be brought in via the Import Page where you can trim the IR, remove the direct part of the sound and adjust its gain to optimise its performance. To create True Stereo HDIR reverbs, you need to load two stereo IRs, where the first stereo file contains left-to-left and left-to-right signals and the second stereo right-to-left and right-to-right signals.

Wizoo have included three different power modes to help out those with slower computers. The difference between these settings is the amount of latency added to the input signal, so if you're mixing (when latency isn't important), this is a good way to maximise your CPU efficiency at the cost of an overall delay of around one-sixth of a second.

System Requirements


  • 1GHz Pentium III or better, 512MB RAM, 56MB free drive space, DVD-R drive for installation, Windows XP, VST or RTAS host.

Mac OS

  • 1GHz Power Mac G4 or better, 512MB RAM, 68MB free drive space, DVD-R drive for installation, Mac OS 10.3.8 or later, VST 2 or RTAS host.

On both platforms, W2 is authorised via the Wizoo web site.

Wizard Reverb

Though there's a lot of control on offer, W2 is actually very easy to use and the first port of call has to be the factory presets. These are based on the 15 included impulse responses, with or without AIR components, and though they don't all have obvious names like 'vocal plate', you can get a very decent plate sound by fiddling with the stone cave. There are also some lovely bright room ambiences that work fantastically well on picked, clean electric or acoustic guitar. If you do decide to render the tail of a reverb to use AIR instead of an HDIR, the sonic difference is very subtle indeed, and even if you render the early reflections part of the patch, the end result is still smooth and musical, albeit with perhaps a little less real room character.

Using the True Stereo programs really does enable you to localise the source much better than would be possible using a blanket mono-in, stereo-out reverb added to the stereo dry signal. Where you need that degree of focus, it is excellent, but most times the standard stereo reverb will do the trick and will save on horsepower. In fact the only thing I totally failed to do during the initial stages of this review was import a third-party impulse response. According to the manual, interleaved AIFF or WAV files will import directly, but I always got a 'not a valid audio file' message. After consulting Wizoo, it turns out that Logic 's AIFF files contain extra data in the header, which is why they are rejected; if you convert them to WAV format within Logic, all goes smoothly. W2 can't import mono impulse responses and I'd found a very nice mono Space Echo IR I wanted to try, so I dropped it onto a stereo Logic track, then saved it as a stereo WAV file, and it worked perfectly. In fact the IR import could only be improved by allowing users to drag and drop IRs into the Import window rather than having to find them via a file browser window.

When reviewing reverbs, it's hard to put across the essential character of what's on offer, and it's also impossible to say which convolution reverb is the best: they all sound differerent, yet they all produce musically believable results. Wizoo seem to have achieved a better sense of focus and space than some of their less sophisticated competitors, especially when using True Stereo mode, but I was also seriously impressed by some of the presets involving the AIR algorithms, especially the '80s drum ambience — which, incidentally, works great on guitar. I'd like a greater choice of IRs, but having said that, I found that I could get pretty close to just about any reverb sound I could envisage, which is a testimony to how easy and effective the editing is. There are also plenty of free IRs on the Internet to try out.

Overall, I really like what Wizoo have done in W2 and I look forward to their forthcoming surround version. It might not have the flashy graphics or compendious libraries of some of its competition but it has a clean-cut interface, it is very flexible without being complicated and it sounds absolutely top-drawer. Definitely worth getting to know better. 


  • Includes a True Stereo mode for better localisation of off-centre sources.
  • Clean and uncomplicated user interface.
  • Excellent sound quality.


  • More included IRs would be nice, but there are no real cons.


There are already some great reverbs on the market but this new offering from Wizoo is up there with the best of them. The ingenious ability to render IR reverbs as algorithmic reverbs or to combine elements of each really adds to the flexibility of the package.


£169; W5 surround reverb £299. Prices include VAT.

M Audio +44 (0)1923 204010.

+44 (0)1923 204039.