Hi,

Is it possible to emulate PWM with this wave ?

Once saw an article about emulating PWM with ramp waves but did not cover it with FM7...

Thanks

If a ramp wave is an inverted sawtooth, then you can get PWM by mixing one saw and one ramp oscillator, slightly detuned. The mix of the two is a square/pulse wave with duty cycle dependent on the phase difference between the oscs.

Thanks for replying !

I believe I have tried "mixing" and detuning the ramp with a saw and the waveform display didnt show anyhting resembling a square wave...only a saw.

The diagram for the ramp wave show the same say with some DC offset, I think...

yul wrote:

Thanks for replying ! I believe I have tried "mixing" and detuning the ramp with a saw and the waveform display didnt show anyhting resembling a square wave...only a saw. The diagram for the ramp wave show the same say with some DC offset, I think...

I don't know much about the FM7. Do you have separate waveform displays for each osc? With one set to ramp and one set to saw, are the displays the same, or is one an "up ramp" while the other is a "down ramp"?

Quote:

If a ramp wave is an inverted sawtooth, then you can get PWM by mixing one saw and one ramp oscillator, slightly detuned. The mix of the two is a square/pulse wave with duty cycle dependent on the phase difference between the oscs.

interesting, that's actually another way, but simpler this time, to do PWM in sytrus. cool.

yul wrote:

I believe I have tried "mixing" and detuning the ramp with a saw and the waveform display didnt show anyhting resembling a square wave...only a saw.

Simply mixing them won't do the trick. Apart from inverting one saw, you also have to offset the phase. With an offset of 50% (180 degree) you get a square wave; all other values narrow the 'pulsewidth'. So rather than detuning the waves, you would modulate the phase offset to simulate PWM. Since so called Frequency Modulation in real is Phase Modulation, it should be possible to do it with FM7 - but don't ask me for the exact math, I guess you'd modulate one saw with a very slow (low frequency) sine or triangle.

I also tried to modulate rampXsaw without results.

Changing the phase is not PM/FM neither.

I dont think it is possible to change the phase in FM7.

That is very weird !

it does kinda work here..

anyway another way is to multiply (not mix) 2 square waves, and modulate the phase of one of them

dr.wackler wrote:

yul wrote: I believe I have tried "mixing" and detuning the ramp with a saw and the waveform display didnt show anyhting resembling a square wave...only a saw. Simply mixing them won't do the trick. Apart from inverting one saw, you also have to offset the phase.

If the two are detuned, they will shift in and out of phase by themselves. When half-cycle off phase, you have 50% pulse width, when they cross being completely in phase, the pulse will briefly vanish into silence (0% pulse width).

Hey Borogove,

Do I have to modulate both saw and ramp operators ?

I am kinda getting something resembling PWM by modulating ramp>saw @65% with slight detune offset and selfmod for the saw.

Is that it ?

yul wrote:

Hey Borogove, Do I have to modulate both saw and ramp operators ?

You should be able to just modulate one with an LFO, and do no other modulation, to get something PWM-ish.