AlenK Posted June 26, 2013 Share Posted June 26, 2013 By ramp I mean a sawtooth waveform that rises when a "regular" sawtooth falls. Yeah, I know, a "regular" sawtooth could go either way but I'm looking for pairs of waveforms that exhibit this relative property (one rises while the other falls). If anyone knows it woud save me from dragging out my oscilloscope. Quote Link to comment Share on other sites More sharing options...
Brad Saucier Posted June 26, 2013 Share Posted June 26, 2013 There is a saw up saw down in the LFO section, but I'm unsure about the saw wav samples. Good question. Break out the oscilloscope. Quote Link to comment Share on other sites More sharing options...
Mike Martin Posted June 28, 2013 Share Posted June 28, 2013 There are reverse saw and ramp waveforms in the XW-P1 to give you this kind of variety. Quote Link to comment Share on other sites More sharing options...
AlenK Posted June 28, 2013 Author Share Posted June 28, 2013 Most excellent. I will explore what I can do with those this weekend. You can imagine what I want to try given my disappointment with the PWM implementation. There may be a ray of sunshine there yet. Quote Link to comment Share on other sites More sharing options...
AlenK Posted June 30, 2013 Author Share Posted June 30, 2013 Experiment complete. I'll start by confirming that pulse-width modulation (PWM) is broken. For exactly what is wrong with it, please see this post: http://www.casiomusicforums.com/index.php?/topic/82-so-you-had-youre-xw-for-a-while-what-would-you-suggest-for-a-update/page-2#entry6596.[i can also confirm that (hard) sync sounds as bad (IMO) as I feared it would, notwithstanding that it is used in many of those "screaming" lead sounds (and is probably why they actually scream!). Apparently, the engineer(s) responsible for the solo-synth "synth" oscillators either don't know how to implement sync in a bandlimited way (which would be surprising because papers on the subject are easy to find) or to be more charitable chose not to do so, perhaps for lack of DSP bandwidth. Specifically, with high sync amounts (large detuning between the oscillators) you get a LOT of aliasing. But if the pitch difference is kept low the sound is not unusable, unlike PWM.]So I tried to create a PWM sound by using the sawtooth wave (0006) on oscillator Syn1 and the reverse sawtooth wave (0009) on oscillator Syn2, with each oscillator at equal volumes. If the pitches are exactly the same you hear nothing, proving that the two waveforms really are inverses of each other. If you detune one, even by only one step, you then hear that characteristic PWM sound with the combined waveform changing smoothly from square to pulse and back again (it passes very briefly through full cancellation). The frequency difference between the two oscillators causes the phase between them to cyclicly change, which sounds just like you applied an LFO to modulate pulse width (or it would if that were working correctly on the XW). The change in pulse width is very smooth, unlike the grainy disaster that is the XW's PWM implementation. (Sorry, Mike. It is what it is.)The problem - and I expected this - is that the speed of change (analagous to the LFO rate in PWM) varies with the pitch of the note. For the cycle speed to stay the same we need a constant FREQUENCY difference between the two oscillators, not a constant pitch difference. Detuning does the latter. Unfortunately, nothing I tried would even approximate a constant frequency difference. For example, I tried using a virtual controller to modulate the detune value with the MIDI key number, figuring I'd get a non-linear curve. I did but it was always the wrong curve, and regardless of the polarity of modulation it always made the problem worse.I'm stumped, at least temporarily (I don't give up easily). Anyone have any ideas? Quote Link to comment Share on other sites More sharing options...
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