How to get a smooth saw in Spire

[Dúnedain]

thank you
But even after Monty I still do not understand it: why does a perfect saw already in digital domain alias?

There is no such thing as a perfect saw in the digital domain. Such a thing would require an infinite sampling rate, as a perfect saw contains frequencies all the way up to infinity. Sure, you could draw samples in the shape of a perfect saw, but the D/A reconstruction of those samples doesn't simply 'join the dots' in linear fashion.

Yes that is what I mean of course, samples/lolliepops shaped like a perfect saw. A perfect saw probably doen't even exist in classical mechanics/ physics

[exmatproton]

thank you
But even after Monty I still do not understand it: why does a perfect saw already in digital domain alias?

There is no such thing as a perfect saw in the digital domain. Such a thing would require an infinite sampling rate, as a perfect saw contains frequencies all the way up to infinity. Sure, you could draw samples in the shape of a perfect saw, but the D/A reconstruction of those samples doesn't simply 'join the dots' in linear fashion.

In other words; the sample rate, or resolution of "parts per second", or slices of data per second, isn't enough to make "a perfect" saw, or pulse, or square. This why the amount of aliasing is going down if you use higher sample rates (192KHz for instance). Technically, there is still aliasing, so it isn't perfect even at those high sample rates, but we can't hear it, because the aliasing is way to high in the high register for us to notice.

[Dúnedain]

Whatever the sample rate: why would a "perfect" saw already in digital domain alias?????

[exmatproton]

Whatever the sample rate: why would a "perfect" saw already in digital domain alias?????

what do you mean with that sentence?? "why would a "perfect" saw already...." <--

[Dúnedain]

Whatever the sample rate: why would a "perfect" saw already in digital domain alias?????

what do you mean with that sentence?? "why would a "perfect" saw already...." <--

after the highest value the next sample is the lowest value of the saw. All other values have linear incremention.

[cron]

Whatever the sample rate: why would a "perfect" saw already in digital domain alias?????

You can not have a perfect saw in the digital domain. The sampling theorem only works properly when signals are bandlimited to half the sampling rate (i.e. nothing above 22.05 kHz at a 44.1 kHz sampling rate). You can't look at the sample points in a digital file and immediately understand what the reconstructed analog signal will look like from those points. It's not as simple as 'joining the dots'. Sure, it's intuitive up to a point, but try playing a saw wave in the 10kHz plus range if you want to take this to extremes. After reconstruction it'll look like a sine wave. The actual sample points (the 'lollipops' in Monty's terminology) will look like noise.

[Dúnedain]

This is what I mean by a "perfect" saw:

after the highest value the next sample is the lowest value of the saw. All other values have linear incremention.

So yes: you can have a "perfect" saw in digital domain. And Spire claims it can generate it, but it can not

[cron]

This is what I mean by a "perfect" saw:

after the highest value the next sample is the lowest value of the saw. All other values have linear incremention.

So yes: you can have a "perfect" saw in digital domain.

Good luck listening to that without converting it to analog first.

[Dúnedain]

This is what I mean by a "perfect" saw:

after the highest value the next sample is the lowest value of the saw. All other values have linear incremention.

So yes: you can have a "perfect" saw in digital domain.

Good luck listening to that without converting it to analog first.

And that is one of my questions: what will go wrong when converting to analog?

[exmatproton]

This is what I mean by a "perfect" saw:

after the highest value the next sample is the lowest value of the saw. All other values have linear incremention.

So yes: you can have a "perfect" saw in digital domain. And Spire claims it can generate it, but it can not

Spire claims nothing??

It shows something in a very small, low res screen. It is just a 'global' representation, not exact science.
You know, Spire is an awesome synth to make some music with I suggest you should use it that way.
If you want some proper science equipment to do exact science, you'll need different gear

[cron]

This is what I mean by a "perfect" saw:

after the highest value the next sample is the lowest value of the saw. All other values have linear incremention.

So yes: you can have a "perfect" saw in digital domain.

Good luck listening to that without converting it to analog first.

And that is one of my questions: what will go wrong when converting to analog?

Because D/A conversion isn't just 'joining the dots' with straight lines. Digital audio would sound pretty terrible if that was the case! It may 'look' like you're joining the dots when you're dealing with lower frequency signals, but that swiftly gets blown out of the water once you get into high frequencies. Take the below image of a very high frequency sine wave approaching Nyquist. The top is what is *actually* reconstructed from the sample points, whereas the bottom is what you'd get if you just joined the dots with straight lines.

[Dúnedain]

Spire claims nothing??

It shows something in a very small, low res screen. It is just a 'global' representation, not exact science.

Ah come on. Whenever you turn one of the knobs the display immediately updates. But when you choose a clean saw the pictures displays the wrong saw.

What do you think the output of the oscillator will be? The output is in fact a "picture" (no not a freq spectrum diagram).

[Dúnedain]

Because D/A conversion isn't just 'joining the dots' with straight lines. Digital audio would sound pretty terrible if that was the case! It may 'look' like you're joining the dots when you're dealing with lower frequency signals, but that swiftly gets blown out of the water once you get into high frequencies. Take the below image of a very high frequency sine wave approaching Nyquist. The top is what is *actually* reconstructed from the sample points, whereas the bottom is what you'd get if you just joined the dots with straight lines.

Thanks, I already knew that. But again: what goes "wrong" when going from a "perfect" saw in digital domain to analog? What aliasing will be introduced?

[exmatproton]

Spire claims nothing??

It shows something in a very small, low res screen. It is just a 'global' representation, not exact science.

Ah come on. Whenever you turn one of the knobs the display immediately updates. But when you choose a clean saw the pictures displays the wrong saw.

What do you think the output of the oscillator will be? The output is in fact a "picture" (no not a freq spectrum diagram).

Listen. Spire never claims a perfect saw. It is 'their' saw. Compare it to hardware devices. Often you can see drawings of the waveforms on hardware synths. Those are "perfect" representations of theoretical waveforms. If one would record a saw from an hardware synth, changes are huge those aren't "perfect" as well.

Besides, the main output is also different when a filter is added for instance.

"Thanks, I already knew that. But again: what goes "wrong" when going from a "perfect" saw in digital domain to analog? What aliasing will be introduced?"

Aliasing is when a soundsource has higher frequency content then nyquist. Because of the steep filter at nyquist, content that is higher pitched then that, will be trown downwards. Mirrored in some sense. This will create a-harmonic content, usually heard in the higher regimes.

[cron]

Thanks, I already knew that. But again: what goes "wrong" when going from a "perfect" saw in digital domain to analog? What aliasing will be introduced?

Right, apologies. I'm going to have to leave that to someone with a bit more knowledge than me. I can only really tell you what it looks like in the frequency domain (mirrored at nyquist) rather than the time domain.