Hi,

This seems pretty obvious, but I am sort of stumped.
If I want to have several oscillators going at mathematically related speeds, how do I get them to line up their zero crossings?

I have three osc~ objects. one at 10hz, one at 20hz and one at 40hz. I am doing some filter modulation and I want these three osc~ objects to be in sync.

In the attached file if I do method 1 I can hear the slowest osc~ object affecting the amplitude of the other two faster ones.

If I do method 2 the osc~ objects get out of sych.

Let me know if someone knows how to do it.

Thanks, Nick

@nicnut A float to the right inlet of [osc~] resets the phase, so if you bang a zero into their inlets at the same time (control rate events are simultaneous at the same logical time) then they will be in phase.
David.

What @whale-av writes is correct. Also note that your first method is actually Frequency Modulation (FM) (missing the index that controls the amplitude of the modulator, of course). The second method is correct for what you want, combined with David's suggestion.

@nicnut If the frequencies are integer multiples of a base frequency, then you can generate them using a phasor, a multiplier and wrap like this:

Hi Everyone.
Thank you again for all the suggestions.
Using threshold~ and sending a zero into the right inlet is syncing everything up

@nicnut I think your solution is fine for low frequencies, but things get funny at higher ones (that aren't really very high at all in the scheme of things, e.g. 87hz). That's because threshold~ has to wait until the current audio block has been processed before it can sync your other 2 oscillators, hence the jump at the yellow arrow. The way I suggested doesn't have that issue.

Hi @jameslo

Ok I tried out your method as I understand it. I am uploading a patch with the threshold~ method and the wrap~ method with the filter modulation so you can hear whats happening.

When I use the phasor~ with an osc~ using wrap~ they all sound the same. Using cos~, as you did in your example, I can hear the different tempos, but it's a different waveform than an osc~.

Is there a way to do use wrap~ with osc~ oscillators?

FilterModWrap.pd

@nicnut [osc~] is equivalent to [phasor~]->[cos~] (and there's no way to mix my way with your way as far as I know), but you're enforcing sync on the positive zero crossing of the base freq oscillator, and my way syncs on 1 (i.e. the start of the cosine cycle). You can shift the phase of my scheme to be equivalent to yours by subtracting 0.25 from the base phasor, thereby making the output of the following cos~ a sine wave filtermodwrap.pd. To my ear, this sounds the same as yours.

But in the title of your thread, you asked how to make all the oscillator's positive zero crossings line up with that of the base freq oscillator. If that's really what you want, then you should shift all the oscillator's phases (filtermodwrap.pd ),

Edit: this used to be much more of a stream-of-consciousness mess, but I saw you hadn't logged on in a while so I took the liberty to revise what I wrote to make it clearer. Ha, and now I see we cross-posted, oh well.

Hi @jameslo

The two versions sound the same to me too. Thanks for the info, even though they sound the same it's good for me to learn how all this works. I also like when things get a little out of synch so threshold~ might be fine for me as well for most cases.

@nicnut especially since the freq is so low, it shouldn't matter. But I agree with you--if it sounds good then that's all that matters.