Polyphony: Snow vs TI?

[Spreader]

Hi,

I currently own a virus snow, but one problem is that I can't run even single "massive" supersaw patch running 8 note unison playing 4 notes. These are of course exactly the type of sounds that the virus is for.

So I am thinking, how can I calculate the polyphony for unison patch using both oscillators? Is there anything I can do to increase the polyphony, besides turning all the FX off?

And finally, does the TI have better polyphony in total integration mode, when playing one patch only? Is it true that the TI also has a unison of 16?

[Timo]

Try using hypersaw instead of patch voice unison.

Using classic saws x 8 unison x 4 note chords = 32 voices. If you have a third oscillator enabled this figure is greater, perhaps 48 voices in total, so it would be toward the limit of the snow's hardware.

Whereas using hypersaw (9 saws [or 18 saws if both oscs are used] while using just 1 voice poly) x 4 note chords = 4 voices, for pretty much the same (or even thicker) sound. Much more economical.

The 'rough' figure for poly for snow is 50 voices (when hypersaw is used), so you can use plenty of release on the envelopes, or even add a little patch unison (within reason) or a third osc if wished without note stealing.

[MBTC]

Polyphony/efficiency of VA synths is always an interesting topic to me. As Timo pointed out, techniques like hypersaw on the Virus, supersaw on the JP8000, or "detune density" (seems oddly named among the three) on the Ultranova can be thought of as techniques / cheats to approach the same type of sound with less processor consumption (allowing more voices to be played at once), whereas I think unison is more straightforward in describing what it does (on synths I'm aware of, at least).

I remember researching this deeply once upon a time, and I believe consensus was that the biggest difference in something like a supersaw of 7 oscillators versus 7 real oscillators that were slightly detuned would be that the CPU/DSP is effectively removing some of the harmonics that would otherwise be emanating from individual oscillators (harmonics that the naked ear might not hear anyway), reducing CPU load and thus achieving a fat sound with less processing required, the thinking being that some timbres would effectively cancel each other out or muddy the waters anyway, so there should be an algorithm that can take the signal from a single osc, multiply and shift it somewhat, then remove that which would not really be heard (by most, under most conditions at least) anyway.

That said, I have no insight as to how the algorithms are actually implemented and I'm sure it varies between synths. However many synths have recognized or emulated the non-linear nature of the detune curve of the JP8000, which results in some interesting characteristics of the final output signal, so many of them strive to implement the same kind of signal (at times paying some level of respect to the JP8000 in how the signal reacts to modulation or knob tweaking, or perhaps putting their own spin on things).

At the end of it all, the nova (the only VA HW synth I have to compare at the moment) behaves much the same way as the virus. If you use all actual oscillators + unison it puts a high load on the DSP, which will requires it to steal notes. If you use alternative methods to fatten each osc, you can get way more simultaneous notes out of it. The end result might not be exactly the same sound, but it's also unlikely that you'd notice the difference in most mixes -- at least you can always use things like compression and EQ to squeeze out timbres you feel are missing.

[TweakHead]

The main difference, as far as sound design is concerned, is that with a super saw like oscillator, you're generating the voices at the oscillator level, while unison duplicates the entire signal, filters and everything included - so it kind of replicates the whole signal, as you would with a multi-patch with the same single replicated with a maximum of 16 parts (on the Virus, no wonder). It sounds different, and for much classic super saw sounds the oscillator simply nukes unison out of the water. For a warm analogue-like kind of pad, for example, then unison would be better, not wacky out of this world settings, just a couple of voices slightly detuned would do the job nice and easy.

The Virus has an almost perfect emulation of the JP 8000/8080 oscillator, sounding almost identical to its older counterpart - there's videos online with such comparisons. Maybe it will benefit from a slight EQ (internal one would do fine), the broad stroke high shelf making the highs a bit more "in your face" - at least that used to be the case up until the Virus C.

[MBTC]

Originally Posted by TweakHead

The main difference, as far as sound design is concerned, is that with a super saw like oscillator, you're generating the voices at the oscillator level, while unison duplicates the entire signal

I know you might be speaking about the Virus specifically but wanted to add the actual implementation of unison can vary quite a bit across different synthesizers. DUNE2 for example (DUNE is acronym for differential unison engine) treats each unison voice separately with different sound parameters for each (or you can treat all voices as one if you want). This is one of the things I love about high-end soft synths, because a typical Core i7 or whatever is so much more powerful than typical hardware DSPs, they plugin can give you the freedom to really go nuts and push limits even if it ends up using up 50% of your CPU -- that kind of CPU usage is really limiting but you of course can freeze it or sample it, which is still better than stolen notes IMO.

I believe in the case of the Ultranova, unison is basically giving you a full oscillator with each voice (a complete representation of the osc signal or waveform), but with detune/detune density it's programmatically making "lesser copies" of the signal which are actually thinner / lower fidelity versions of the signal (which, when stacked together of course give a similar effect). Think along the lines of something like synths that give you quality options (eco/draft mode for the sound) to help manage CPU resources. For example your ear can hear the difference between eco mode and best quality mode on most synths, but in a mix and after run through other effects it would be harder to notice on most sounds in most music types. The Ultranova printed manual actually makes a specific point that most of the factory patches use detune density (hypersaw trick) instead of true unison.

[MBTC]

@Timo (since you're in the envious position of owning 2 Viruses):

Can the limitations talked about here be overcome by layering multiple Viruses in some way? By that I mean is it possible to create a patch on one of them, dump it over to the other one and run a slightly modified version on the second synth? For example a supersaw lead might normally have some of the voices playing down one octave lower, so for example the indigo could play some voices at high octaves and the snow fill in the lower octaves? Overall polyphony could be increased (not to mention thickness of sound) because less unison voices per synth could be used.

It's a multi-faceted question of course, the basis of which rests on patch compatibility between the B/C series and the TI, I'm guessing, but at the end of it I'm just wondering if polyphony challenges can be addressed with multiple viruses (not in the sense that they truly talk to each other or sync up in the true spirit of daisy chaining or anything).

[TweakHead]

yeah, was talking about the Virus alone. Dune is one of the best implementations of Unison to my mind as well, was so with version one - that I know, haven't tried the second yet, but seems like great beast to tame.

Have you got it?

@Timo

expecting you inject some enthusiasm back in here certainly hope so!

[MBTC]

Originally Posted by TweakHead

yeah, was talking about the Virus alone. Dune is one of the best implementations of Unison to my mind as well, was so with version one - that I know, haven't tried the second yet, but seems like great beast to tame.

Have you got it?

Yes, and it is amazing, perhaps my new favorite instrument. Only an $80 upgrade if you owned Dune1. But this is much more than just a new version, it blows Dune1 away.

[Spreader]

Thanks for the answers guys. They were more interesting than I had anticipated and made me ponder what constitutes a good unison in the first place.

So let's do some quick math. Let's say the longest note that is going to get played is 1 second long which nets us frequency resolution of 1hz. Our detune amount is 40 cents for that trance 2.0 supersaw.

The first obvious question is, how many saw waves do we want? For maximum tweakability there should one saw wave for each frequency bin. At 16khz that's around 400hz. So the answer is 400 saw waves.

But this becomes immediately problematic because at lower frequencies such as 100hz the 20 cents is only 10hz. So the tone is not going to be consistent there. Further problem is that in higher frequencies the harmonics will overlap when playing low notes, so they are not going to be consistent either.


Seems like this is in fact a really tricky, possibly unsolvable problem... Oh well. Just use your ears then.


My ears tell me that Supersaws where the saws overlap sound terrible, metallic and so on. In other words, when using massive amounts of saw waves to get those nice smooth highs, the most important thing in the implementation is very high frequency resolution. For example in the prior scenario the resolution needs to be 20/400 = 0.05 cents. No digital synth can possibly pull that off...

Does anyone know what the resolution of the virus TI is? 1 cent?

Anyway, the resolution problem maybe responsible for more terrible metallic sounding supersaws than can be calculated here. Or perhaps it's just the way that some synths tend to detune the saws on top of each other...

[Timo]

Originally Posted by TweakHead

@Timo

expecting you inject some enthusiasm back in here certainly hope so!

Got lots to add, and will address points made. Been away again with choppy wifi for the last 9 days, really frustrating. Will be back home tomorrow.

Was putting both viruses through their paces and doing tests with the Hypersaw before I went away. It does indeed work differently to normal patch unison and depending on the application one does work better than the other and equally importantly vice versa. They are different tools and both have strengths and weaknesses which the other addresses, so it's nice to have both. However the classic sound engine holds its own well with a few tricks.

More tomorrow.