Is ‘scanned synthesis’ the best thing since sliced bread, or a triumph of hype over substance? We put Humanoid Sound Systems’ Windows soft synth on the test bench to find out.
“Really? It sounds like a bad Minimoog copy.”
“Well, yes. But hey, we’ve made the graphics look like a crashed alien spacecraft...”
Humanoid Sound Systems claim that Scanned Synth Pro is “considered by many to be the most exciting innovation in computer music and audio in the last ten years”. As a paid-up cynic, I was half-expecting ‘scanned synthesis’ to be another fancy name for something underwhelming and over-familiar. Happily, I was wrong, and although it might not quite be the innovation of the decade, I think it is a technique that has a real future. It has previously been implemented in academic programming environments such as Max and CSound, but Humanoid Systems say that Scanned Synth Pro is the first product to present it in a user-friendly fashion targeted at musicians. SSP is a VST plug-in for Windows, which is activated by entering a user name and serial number.
So what, exactly, is scanned synthesis? Those of us who are not frightened of equations can learn more than I could possibly explain here at www.billverplank.com/ScannedSynthesis.PDF. For the rest of us, the easiest way to understand it might be as a development of wavetable synthesis. In classic wavetable synths such as the PPG and Waldorf Wave, conventional oscillators are replaced by a digital read-out of a series of values representing a single cycle of a sound wave. The pitch of the resulting note is determined by how fast the wavetable is read out.
Typical wavetable synths contain tends or hundreds of different wavetables, some of which mimic the classic square, sine and sawtooth waves familiar from analogue synthesis; others might be designed to recreate timbres from acoustic instruments or even the human voice. Simply reading out the same wavetable over and over again results in a very static sound, so wavetable synthesizers usually offer a variety of ways to move between different wavetables as a note is being played, to generate variation in timbre.
However, in a typical wavetable synth, the wavetables themselves don’t change: they are all calculated in advance and stored in ROM or RAM. The key idea behind scanned synthesis is to replace this list of stored wavetables with measurements taken (or ‘scanned’) in real time from a single, dynamically evolving system. Because the system is continually changing as it is being scanned, the timbre of the resulting sound is always changing too.
There are, presumably, an indefinite number of mathematical models that could be used as a basis for scanned synthesis, but Scanned Synth Pro uses only one. This simulates a circular string of point masses connected to each other, and also to fixed resting points, by springs. When a note is played, these ‘nodes’ are set in motion, and kept moving, by a shaped ‘hammer’.
It’s important to note that what’s going on here is not the same as in physical modelling synthesis: Scanned Synth Pro is not attempting to recreate the sound that a real network of springs and nodes would actually make. (In fact, as the network itself is designed to vibrate at frequencies below 15Hz or so, it wouldn’t be suitable for this purpose in any case.) Instead, the shape formed by the network is scanned at intervals and turned into a wavetable. As the shape changes, so does the timbre of the resulting sound.
If that makes no sense, fear not: as the manual insists, “you can enjoy using Scanned Synth Pro totally productively without understanding the details of how it works at all!” Now that’s my kind of a synth...
User control in Scanned Synth Pro is mainly directed at shaping the way the network of masses and springs behaves. The most important synthesis parameters address six aspects of this model. Until it is struck by the ‘hammer’, the network of nodes is at rest. The shape it forms when at rest is determined by the Centre Wave controls, and can be a flat line, a sine wave or a ramp. (In theory, therefore, SSP would produce an unchanging sine-wave tone if you set the Centre Wave to Sine and turned the hammer action off altogether.)
The simplest way to visualise the network of nodes is as a circular string, with each node connected by a spring to its immediate neighbour on either side. However, this being a mathematical model and thus free from real-world engineering considerations, you can also choose a number of alternative configurations where, for instance, each node is connected to its opposite number on the other side of the circle, or in a “small-world network”. These are chosen using the Connection Types pop-up, and some configurations can be modified in real time using the Warp control. Naturally, the pattern of connections, and their strength, has an effect on the behaviour of the network.
When the network is set into motion, it ‘tries’ to return to the shape set by the Centre Wave, thanks to the additional springs that connect each node to a fixed point. The Strength parameter in the Centre Force Scale group of controls determines how powerful this homing instinct is. To further change the way the network of nodes behaves, you can make some of them heavier than others; heavier nodes naturally have more inertia than lighter ones. This distribution of mass is controlled by the Mass Shape parameter, and again, is represented as a waveform.
Finally, the behaviour of the network of nodes is also affected by the shape of the hammer used to ‘hit’ it, and by how hard it is struck. Once again, the shape of the hammer is described as a waveform, in this case, with sine, square and sawtooth waves to choose from. Overseeing the whole model is the Update Rate control, which in effect, acts as a global frequency control, determining how quickly or slowly the whole network moves. The final synthesis parameter is a simple button labell ed Psycho. For some reason, this is located on the Filter page of the interface, but its actual effect is to remove restrictions that are normally placed on the synthesis model to prevent the masses flying off into space or otherwise ending up in extreme configurations.
Within the model, anything can be modulated that it would make sense to modulate, and two LFOs and two ADSR envelopes are available for the purpose. The resulting sound is dynamically shaped by a further master envelope, and passes through fairly conventional effects and filters on its way to your ears. The former comprise flanger, chorus, delay and reverb, while there are two filters. The first is a polyphonic design, with cutoff frequency that can be modulated by the envelopes or LFOs, while the second is a global filter affecting the entire output of the synth. Both filters offer a range of low-pass, high-pass, band-pass and other shapes.
The Master page includes the usual global parameters such as polyphony and portamento settings, and there’s also a MIDI Learn facility which applies to every SSP parameter, so it’s easy to set the synth up for real-time control.
Perhaps the best way to get to know SSP is through its clever random patch generator. Most of the important SSP settings include an additional control, which does nothing in itself, but sets how much freedom the random patch generator has to alter that parameter. This means that an SSP patch can serve as a ‘seed’ for the random patch generator, allowing itself to be modified randomly, but only up to a point, or in certain respects. Many of the factory patches exploit this nicely, so that clicking the Randomise button generates a new sound that is recognisably related to the one you started with. You can get a long way in programming SSP by clicking the Randomise button until you hit on something you like, before embarking on fine-tuning as necessary.
One of the strengths of scanned synthesis, as opposed to other digital techniques such as FM and granular synthesis, is that anyone used to conventional subtractive or analogue designs will immediately notice a similarity between the way that, say, a sawtooth oscillator in an analogue synth sounds, and the timbral properties of a sawtooth Centre Wave or Hammer in Scanned Synth Pro. Beyond that, things get unfamiliar pretty quickly, and programming an SSP patch from scratch can be a hit-or-miss affair to begin with.
Most of the controls in the the Centre Wave, Hammer and Mass Groups have audible and repeatable effects, but some of the others either make very little difference, or don’t do quite what you’d expect. For example, even making radical changes to the configuration of the nodes in the Connection Types pop-up frequently has no audible effect unless the Mass Scale parameter is set very low and the Psycho button engaged. After a while, though, you begin to get a sense for what will and won’t make a difference to the sound, and the total number of synthesis controls is small enough that you won’t be overwhelmed by choices. And while I was still feeling my way around the controls, I got good enough results through pure luck that I never became too frustrated. In conjunction with the Randomise function, the presets make an excellent jumping-off point for further exploration.
There are a few minor bugs in the user interface, the most obvious being that selecting items from pop-up lists doesn’t work properly unless you do it twice. Elsewhere, one feature that I often found myself wishing for was some sort of random or sample and hold waveform for the LFOs — it would be great if this could be added in a future update.
I like a synth with an individual sound, and Scanned Synth Pro has personality and character in spades. In particular, it excels at dark, textural sounds, both musical and unmusical. From grinding waves of turbulent noise, through wheezing, diseased string machines, to eerie pads that sound like someone playing sheet steel with a violin bow, it seems to create an unsettling, ominous atmosphere without even really trying. In a couple of hours’ playing around, I came up with a pretty convincing pastiche of Another Green World-era Brian Eno, and SSP will also have obvious and happy applications for anyone making industrial or experimental electronica. Sound designers will also have a field day, especially if they’re working on horror soundtracks. At the other end of the spectrum, though, SSP is also capable of producing some surprisingly punchy analogue-style bass and lead parts that would work in the most conventional of dance tracks, and its pads and strings can be pretty as well as gritty.
Perhaps its greatest strength, as far as I’m concerned, is that although SSP is not the sort of thing you’d use to emulate acoustic instruments, it seems to produce sounds that fit well into an arrangement, whether it’s surrounded by electronica or live recordings. There’s little of the glassy, unreal quality that can make other types of digital synthesis so hard to work with in a mix.
Dissecting some of the presets makes clear that Humanoid Systems were wise to incorporate conventional filtering and effects sections into Scanned Synth Pro. The filters are often very handy when it comes to taming the high frequencies, and many of the more abstract sounds would be lost without a heavy dose of chorus. Usually, I’m not too keen on synths that depend heavily on effects in order to sound impressive, because it can make them hard to use in a mix. However, although there’s nothing particularly extraordinary about the effects included with SSP, they do seem to integrate very well with the scanned synthesis, and you often don’t realise how much the effects are doing until you switch them off.
Overall, I like Scanned Synth Pro a lot. It does have a few rough edges, it crashed once or twice on my machine, and programming patches can be a bit of a black art, but the bottom line is that SSP is an original and innovative synth with a fresh and distinctive sound. Most important of all, as far as I’m concerned, is that although scanned synthesis might appear academic and abstract in concept, it’s actually very usable in real-world situations. Scanned Synth Pro has already brought a new dimension to the projects I’ve used it on, and I look forward to seeing how Humanoid Systems develop it in the future.
At 90 Euros, Scanned Synth Pro is unlikely to break the bank, but if you want to explore scanned synthesis for free, you could download its little brother. Scanned Synth Mini is actually exactly the same synth, the difference being that you can only change settings through the Randomise button: there’s no direct access to the controls. Since the random patch generation in Scanned Synth Pro is actually very effective, this makes Scanned Synth Mini a surprisingly powerful beast.