Additive oscillators

I'm loving the crisp, tight sound of the Virus - it's making me realise what I've been missing with a lot of soft synths. However, there seems to be a growing fashion for additive synthesis - and the sounds available using an additive synthesis engine are interesting, diverse and powerful. Software synths like Razor and Harmor have shown that the seemingly bewildering concept can be broken down into an easy-to-use, familiar format.

It would be really interesting to have the ability to swap out a couple of oscillators for additive oscillators (with a selection of pre-created additive waveforms) and plug in a pair of additive processors while still within the additive engine, before it drops back to the subtractive engine to use the classic filter and effects sections. I think this 'best of both worlds' approach would give the Virus a unique edge.

I do, however, accept that the amount of development time and processing power required may well be prohibitive.

I didn't think of FM and RM as additive, more as waveform modulation techniques. (I see an additive engine as being one where the final output waveform is constructed from a number of sine waves of different pitches, phases and amplitudes. FM and RM take existing waveforms, sometimes already complex, and multiply them.)

I think the uniqueness of the operations within the additive engine come from the way that the resultant sound is utterly, unashamedly digital. The fact that the algorithm is playing with sine waves rather than complex waveforms makes for a particular kind of precision. Also, it's possible to think up additive tools which work in ways no analogue-style filter or effect could. Detuning selected harmonics is one. The 'filters' and effects you find on Razor and Harmor can make some remarkable sounds.

I'd love to hear how all that works as a stage before the rich analogue emulation of the Virus. But like I said, it's a lot of work - and would probably take a hell of a lot of DSP power.

> Additive synthesis takes base oscillators and creates new harmonics with its processing. FM and RM do this.
OK, if you like. We're getting hung up on semantics though. FM and RM simply aren't what I'm talking about. They work in a completely different way and they produce very different sounds.

Based on all I've read regarding different synthesis techniques to date, I think of 'FM' and 'additive synthesis' as different classes of synthesis. What I call 'additive synthesis' uses the addition of many partials - all sine waves and all individually malleable - to create the final waveform. FM, RM and I guess PM are all carried out using the multiplication of audio frequency waveforms, often complex ones.

What would you specifically call what I refer to as 'additive synthesis', just so we're using the same language? If, for example, you didn't want to lump it in with FM and RM?

> Also, frequency domain manipulation is not so intensive, thats how digital vocoders work. You can quite comfortably take the FFT ...

But rough FFT approximations aren't how additive engines work. They model the individual sine waves in order to give that characteristically crisp, digital sound. I do know that even a simple additive patch on Harmor or Razor will eat CPU like it's going out of fashion. Could be bad programming, but I suspect the calculations are intense.

Interestingly, given your description of subtractive, both Harmor and Razor would fit the bill. Looking at the interface, they use complex oscillators at the start of the signal chain and everything afterwards alters the frequency components. The difference is the engine and the new sonic options allowed to you thanks to the ability to play with individual sine waves.

The Virus isn't an FM synth. It gives a limited FM option so you can add an FM flavour to sounds. I'm suggesting a similar thing when it comes to additive synthesis. The ability to add an additive engine component to the signal path to add some of its flavour to the synthesis.

This is all fascinating stuff, but come on, *you know what I mean*. Both Harmor and Razor show you a graphic representation of the partials as you manipulate the processors and oscillators. They can do this because each partial is modelled individually. Unlike with FM or RM, where such modelling isn't necessary and everything can be carried out using simple analogue components if desired.

(I believe audio imports are converted into their corresponding internal partial representations before hitting the synthesis engine in Harmor.)

So basically, I've found this particular partial modelling technique to produce an interesting and powerful sonic palette. If you want to create the name 'spectral remapping' for it then fine... Although I don't think the phrase quite does it justice and... well, 'additive synthesis' perfectly describes what I mean already, according to Wikipedia for one:

: Additive synthesis is a technique of sound synthesis that creates musical timbre by explicitly adding sinusoidal overtones together.
: The timbre of an instrument is composed of multiple harmonic or inharmonic partials (individual sine waves), of different frequencies and amplitudes, that change over time. Additive synthesis
: allows the emulation of a given tone or sound by giving control over the frequency and amplitude of each individual harmonic or partial. In general, each harmonic generator has its own
: customizable amplitude envelope and instantaneous frequency function, creating a realistic, dynamic sound that changes over time.

Specifically this:

:Additive synthesis allows the emulation of a given tone or sound by giving control over the frequency and amplitude of each individual harmonic or partial. In general, each harmonic generator [partial] has its own customizable amplitude envelope and instantaneous frequency function

Have I done enough yet to narrow down what I mean to you?

And rather than splitting hairs with terminology or using inappropriately broad categorisations to imply that the Virus does this in some form already(!), what do you think of the idea of the feature? Do you think that the Virus can already do everything that it could if it had an additive engine component?

By the way, where did you get your definition of additive from? As I said, everything I've ever read about additive synthesis agrees with the Wikipedia entry, and I've been interested in synthesis for a fair while now. You obviously know your stuff, so what's your source?

Thanks!

That article sounds oddly familiar, especially the crack about the Hammond Tonewheel Additive Synthesizer. It could well be one of the very articles I read about different types of synthesis many years back when I had a SoS sub.

Again, it seems to reinforce my understanding of additive synthesis and in particular the architecture of Razor and Harmor. They appear to have cracked the idea of using a single osc for each harmonic, each independently controllable.

The more I think about it though, the more I think that an additive engine would utterly swamp the resources available to the Virus.

Zitat von AtonyB

Yes it is, of course, possible to have a bank of oscillators, each modelling each partial - I have no idea if that is how Harmour works (you could just work in frequency domain)

Unless the press release and instruction manual are lying then yes, that is how it works. They could be lying of course, I haven't decompiled the code or anything. But they call it an additive synth, describe it as using an oscillator per partial and, indeed, additive synthesis is defined as the use of an oscillator per partial (unless you can show me a source more reputable than SoS and Wikipedia which supports your definition. Perfectly possible to do of course, I just haven't seen it yet.)

Zitat von AtonyB

- but in the case of the Virus, it has 80 voices, so you can guess how quickly you would run out of voices...

Unless, maybe, it's possible to optimise a simple sine wave oscillator in a way that you can't with, say, an oscillator capable of pulse width, wave shape, triangle, saw, square etc.

Zitat von AtonyB

Be comforted by the fact that using wavetable synthesis and the variants on the Virus you can get a lot of the harmonic modulation effects you might want from there

Having a wavetable oscillator isn't like having an additive engine. It's lovely to have and there may be ways to get some similar sounds (depending on the wavetables you're given) but it's not the same.

Zitat von AtonyB

and using the formant shift you can get a lot of great sounds which are easy to keep in check.

All of the Virus features are capable of giving you a lot of great sounds. The virus is a great synth, that is why I shelled out a possibly unwise amount of money on it. But this thread is about feature requests, surely, not listing existing features and saying how great they are?

If I want a sound that an additive synth will do well, I'll go to Razor or Harmor.

Zitat von AtonyB

Personally I'm not that impressed with Harmor, it was going cheap and I wasn't persuaded, but I parted with over £1000 for the Virus, so what does that tell you?

Horses and courses. I love 'em both and I ended up buying it.

Zitat von Shesh

Why not just create a multi patch using 16 parts (16x3oscs = 48 oscs!) to generate the required partials > record > send back into Virus to filter/apply fx etc?

A little convoluted but still seems doable.

Awesome. After a quick scan through the manual I found the feature you're talking about, 'Input Mode'. In theory that means I can use any synth I like to generate a waveform to be shaped by the Virus filter section (and ring modulator by the looks of it). For monophonic sounds that could work - and no recording would be required. (I could pipe a soft synth through a spare output and into the Virus.)

Nice. Now if I can sort out the hideous MIDI timing issues I get when using my sound card, I shall play.

I see. So a modification of the hypersaw to turn the oscs into sine waves and snap them to the harmonics. (Or a knob to pull them there over time, why not?) A dial to change the harmonic components used (saw to square to other interesting waves) then a few knobs to control some tasty frequency domain/phase effects.

Great thinking. Only problem I can see is that the hypersaw only has 9 voices IIRC. 18 with the sub oscillator, but I have a feeling that's a clever optimisation. If you disabled the second oscillator I suppose you could get 32. Halve the polyphony from an already severely limited range and you get 64, which is beginning to get there...

But I think Razor has 320.

I guess it would have to be a balls-out 'this feature will be monophonic, alright?' type setting for arps, leads, basses and the like, but on reflection I think it would probably consume the whole machine.

Fair enough. Maybe it it possible, and that would be gorgeous. Depends if the programmers feel that the sonic palette is worth it.

Knowing my luck the Virus TI3 will come out next month with four times the DSP, USB 2/Firewire, the ability to offload work to the host CPU, additive, 6 operator FM and physical modelling. ;^)