Quick pulse-width question

[Timo]

Think I'm missing something here, but how can you control the pulse width of a Saw wave as easily as you can with the Square wave? The pulse-width knob control only comes in effect when using the square/pulse waveform only? I understand the knob, after turning it anti-clockwise from 12'o'clock, selects the spectral wave for that oscillator. However, I'd like to be able to affect the PW of the saw wave too (and/or the spectral waves as well, although I would understand this would be considerably trickier, if indeed at all possible, although most likely not).

Thnx,

Timo

[Tomer=Trance]

pulse width only works with pulse\square wave

[hatembr]

tomer i think i understand what timo wants, he's talking about varying the the waveform's phase... i think it is not possible on the virus. Actually i've never heard of any synth doing that.

[saba]

I don't see why you would want to do that with the waveforms? It doesn't alter the sound at all
________
Effects of depakote

[Tomer=Trance]

you could do it manualy and then prosses it thru the virus i guss
maybe ask blank he will know for sure

[hatembr]

i think this is what he wants to do:

http://www.freewebs.com/hatembr/img/saw.gif



and i think it does change the character of the sound.....

[Blank]

There is no pulse width with saw waves...the only way to be able to get a pulse width modulation would be to mix a saw with a square...i have noticed tho that if u turn the shape knob half way or more towards square u can modulate the pulse width...which would give u somewhat of the effect u r looking for...but from what i know u cant modify saw waves like that...the only thing similar is frequency/pitch change...that shrinks and grows the cycle of the wave form...the deeper the pitch the longer the wave cycle and the higher the shorter the cycle...but just look at a square wave vs a saw...and u will notice that it is not possible...the saw does not have all the characteristics of the square for it to be able to do it...

peace
Blank

[Tomer=Trance]

and syncing them as the saw a slave osc right?

[Timo]

Thanks for all the responses.

I've read the manual all last night and I've come to the conclusion that it's not possible to do this on the Virus! I'm actually extremely surprised the Virus doesn't do this, as it's a very powerful and expressive (yet very basic) technique. I often use it on the Moss (Z1) board for my Korg Trinity as a programming technique - It's excellent for brassy-type stabs and sounds and as an extra alternative to detuning or unison for increasing the 'fatness' of a sound. It might well be possible why the Virus can't re-create the JP80*0 supersaw (as per on another thread), too?

Basically the PW controlling a square/pulse-wave alters the pulse-on/pulse-off ratio. However, when using pulse-width on something like a sawtooth, it shifts one of the 'transients' of the single-cycle oscillator waveform towards, or away from, the next transient of the sawtooth.
Whereas a square/pule wave with a pulse-width ratio of 100% leads to 'silence', a saw wave at 100% would sound as though it had doubled up an octave. Modulating the PW of a saw-wave with an LFO would make it rock gentley from one octave to the next as the middle-transient of the waveform cycle moves away from its 50%:50% pulse-width ratio.

To make it easier to see what's happening, I've grabbed some waveform images of what happens on my Z1 (Moss) board VA when modifying the PW of a saw:



/\ Above shows a standard sawtooth with an overall pulse-width effect of 0% - no effect.



/\ Above shows the sawtooth with a pulse-width effect of 25%.



/\ Above shows a pulse-width effect of 50%.



/\ Above has effect of 80%.



/\ Above shows 100% pulse-width effect - in effect, it's doubled the frequency, hence sounds like it's an octave higher.

I guess, therefore, it'd be emulatable by using two oscillators, one of which is an octave higher, and then crossfading between the two, but it's far less powerful, uses more resources (ie. ties up two or more oscillators) and is more elaborate and fussier to implement.

Anyway, if you're wondering what the original/actual version sounds like on my Moss...

A standard sawtooth oscillator is:-

[Sawtooth]

An example of what a single sawtooth oscillator with pulse-width modulation sounds like:-

[Pulse-width modulated by LFO]

Two detuned saw oscillators each with independant PW modulation:-

[2 x detuned saws PW-modulated]

.... and that's without unison/unison-detuned, and in mono.

An old example I made showing saws and PW was this:-

[Brassy saw stabs]

Aw bugger, hope they implement it in the next Virus, with as flexible wave-bending capabilities of Z3ta+!

Timo

[hatembr]

8O