|polyKB II :
|"It is a fantastic sounding soft synth! It is certainly one of the best virtual instruments that I ever got my hands on, and I will be using it on many of my upcoming productions!"
The XILS V+ is based on a Top Octave Divider oscillator.
Under this strange name is hidden the heart of almost every electronic organ or strings machines built in the 80's.
A very clever concept to get 49 notes or more of polyphony without having to manage 49 or more stable oscillators, or the nightmare of having to tune 49 or more oscillators !
Only one square oscillator, oscillating at a very high frequency (the "Top Octave"), has to be designed and adjusted
This oscillator is "divided" to provide the 12 standard tempered frequencies over 4 (or more) octaves, these frequencies are then used to build the waveform of each of the 49 or more available notes.
As a mater of fact, all the notes are kept in phase, hence no drift between octaves (see the videos comparison between the hardware and the software)
An other benefit is that there is only a single tuning circuit for the whole keyboard and then when using the envelope glide, all the notes are modulated in the same manner.
This is the limitation which gives this very special, very recognizable effect used by a lot of electronic music artists.
Two other consequences :
The first one is that the attack is done after the summation of the notes. This means that after a note is played the others will get the level reached by the fist one.
In other words No polyphonic attacks for the real machine, but XILS-lab, thanks to the computer world, offers you both, monophonic AND polyphonic attacks.
The second consequence is that all the filters are done after the summation of the notes. The filters (strings, Human Voices, Vocoder) are then also monophonic.
49 voices of polyphony wouldn't be possible on todays' computers if the 49 specific filters would have to be polyphonic too (human voices are done with up to 14 filters, strings involves 7 filters, so up to 1029 filters would have to run at the same time ...).
So, as the real machine, the XILS V+ has monophonic filters.
Anyway XILS-lab brought a lot of other Polyphonic modulation or parameters :
But listen to the result !