I think Gen30 will keep all (also the non-integer) partials up to the
top one. If I understand it correctly, the upper partial can be
thought of as a "filter cutoff frequency" sort of.

The phase synced interpolation you want can be done with partikkel by
using the 4 available source waveforms and crossfading between them.
There might be a simpler way of doing it too, just using regular
oscillators as you suggest.
If you use partikkel, you can change the source waveforms at k-rate,
so you can dynamically evolve your timbre over more than 4 waveforms.
You can also link several partikkel opcodes phase synced via the
partikkelsync opcode.
With partikkel you could also do fm on the source waveforms, and with
some care you could also do phase modulation.
This will indeed be a complex setup, but it seems your idea requires a
quite complex instrument in any case.

And, btw, I do have an example of PSGS with partikkel. It does formant
transposition quite nicely. I haven't shared the example yet because I
wanted to see if I could get pitch transposition to work smoothly as
well. It seems the description of PSGS in microsound is not sufficient
to create pitch transposition without audible sidebands but I have
some other ideas to try out.

Oeyvind

2008/1/23, Tim Mortimer <timmortimer@d2.net.au>:
>
> I'm back! ; )
>
> So i've been browsing the manual this evening, trying to find out what's the
> best way to go about designing some "crossfading oscillator" synthesis
> instruments with Csound, & to be honest i'm a little uncertain what is the
> best way to proceed (as mostly up until now for me Csound has been about
> sample playback or resynthesis in one form or other).
>
> I touched upon some alaising concerns in an earlier post (about 6 weeks or
> so back..) & yes, "aliasing happens!" Anthony Kozar ; ) ... but, err, i'm
> still not sure how to approach this.
>
> I'm concerned because i am likely to want to use square & impulse &
> generally "pointy" like oscillator shapes, but i also want to be able to
> crossfade the oscillator shape during playback with other "found" & "random"
> type shapes (snipped from samples or created in text file) or other more
> additive GEN routine based ftables even (do i dare add FM to the mix at this
> point?), to create diverse & changing spectra in a single crossfadeable, but
> phase aligned synthesis method.
>
> now the obvious thing to do to start this would be use some sort of oscil
> based table read - but surely (from what i can gather reading the manual..)
> VCO2 & GEN30 (???) are designed to overcome any aliasing issues
> (particularly again with those "squarer/pointy" waveshapes..) by performing
> some sort of analysis on the "spectra" implied by any given oscillator
> shape, & reproduce the signal band-limited to within Nyquist safe regions?
>
> So do i load all my oscillator shapes in a bunch of ftables, analyze them
> all in separate gen30's to bandlimit the spectrum to appropriate levels, &
> then tablemix from these / selected GEN30's to create the desired effect??
>
> GEN30 manual entry does refer to "harmonic partials" - does that mean it
> creates a sine based reduction of integer value frequency ratios only, &
> doesnt represent the complete spectra in all it complexity?
>
> Alternately, i'm not sure any VCO2 based implementation is going to make the
> job of crossfadeing phase-synced oscillators any easier....
>
> I know what i'm looking for for the rest of this synth design
>
> > LP/HP/Notchfilters
> > allpass filters
> > envelopes
> > feedback, pitchshifting & modulating delaylines
>
> to mainly create some nice classic ambient pad sounds that can "expand
> upwards" into lots of top end sizzle!, but i wan't to make sure i get the
> cross fadeable phase synced oscillator section right, particularly when i
> can't phase sync gbuzz or the like to get nyquist friendly pulse waves that
> way, so basically I have to look at some sort of table based alternative it
> seems to keep the "pulse oscillator state" in phase alignment with the other
> less harmonically rich oscillator shapes...
>
> There are plenty of Synthesis gurus on this list. Do any of you have any
> useful advice as to how i might best proceed with this?
>
> I also recall the recent crossfadeable Waveshaping discussion, & wonder if
> as part of that there was a method i might borrow to perhaps better align
> tablemix transitions to zero crossings in the wave playback for
> example...??? (as opposed to simply at constant krate - but that hopefully
> would be ok anyways as long as the crossfading wasn't to ambitious in terms
> of speed of execution...) - Anthony, did you achieve this "transition of
> crossfade at 0 crossings only" at all? Was it necessary to achieve the
> effect u were after?
>
> Please share your experiences & insights & suggestions!
>
> & many thanks as usual.
>
> T.
>
>
>
>
>
>
>
>
>
> --
> View this message in context: http://www.nabble.com/phase-synced-crossfade-synthesis-without-aliasing---how--%28-Gen30--%29-tp15037443p15037443.html
> Sent from the Csound - General mailing list archive at Nabble.com.
>
>
>
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