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Hard Sync Sound with Oscillator 2 and 3

JayT

Hard Sync Sound with Oscillator 2 and 3
« on: October 04, 2021, 11:38:54 AM »
After I read the comment https://www.thomann.de/at/sequential_pro_3_reviews.htm?rating=2 I recreated the mentioned problem with sync of Osc 2 and 3. Following the instructions in the manual but with Oscillator 2 and 3 instead 1 and 2, it is really hard to get a stable sync sound. After playing with the coarse tuning it is possible to get a step closer, but it doesn’t sound right.

Does anyone else recognize that? Is there a explanation, why it sounds so different?

For me, this is not an issue since it produces really awkward sounds that might lead to something interesting. If I need a classic sync sound, Oscillator 1 and 2 work fine. But I’m curious about why this is the case.

chysn

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Re: Hard Sync Sound with Oscillator 2 and 3
« Reply #1 on: October 04, 2021, 09:12:04 PM »
I like the behavior because, as you mentioned, there's some interesting sonic territory, and there's a perfectly serviceable way to get a "traditional" sync.

With oscillator sync, the only thing that matters (in terms of wave reset) is the period of the controlling oscillator. You'll notice that the selected wavetable doesn't matter, and the current wave shape also doesn't matter. The only thing that matters is how often the wave starts a new cycle.

And the cycles on Oscillator 3 are weird, due to how they're stored in memory. At low frequencies, it's a single 1024-sample waveform, then there's a single 512-sample waveform, then two copies of a (downsampled) 256-sample waveform, and finally eight copies of a (downsampled) 128-sample waveform. My best guess is that Osc 2/3 sync behaves so differently because of these variations as Oscillator 3's pitch changes. A regular frequency "sweep" isn't really very regular. The eight-copy range comes in sooner than you'd expect (around F5), and so your Oscillator 2 reset starts happening a lot, causing the timbre to kind of "break up" like it does.

I'm not totally sure, but I suspect that there's some math going on behind the scenes that takes advantage of these downsampled copies by increasing the software's actual played wavelength. Higher frequencies are maybe an illusion and this gets reflected in sync.

The workaround is to keep Oscillator 3's pitch low. You're in the highest-quality 1024-sample section of the waveform up to around F2, so stay below that. Or, even better... embrace the instability.
« Last Edit: October 04, 2021, 09:21:39 PM by chysn »
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JayT

Re: Hard Sync Sound with Oscillator 2 and 3
« Reply #2 on: October 05, 2021, 09:40:28 AM »
This is a good explanation why the notes sound so different.

I'm still not sure where the „quantized“ sound of the Oscillator 2 pitch envelope comes from.

As far as i know, the sync button on Oscillator 2 restarts it whenever Oscillator 3 finishes its a cycle. Is this correct? If it is, then I would think, that a digital oscillator is even more stable than an analog one.

Quote
And the cycles on Oscillator 3 are weird, due to how they're stored in memory
This is most likely the explanation for what I hear.

Im still a bit confused though about this, even if it can lead to unusual and interesting sounds.
« Last Edit: October 05, 2021, 09:59:53 AM by JayT »