Elektron Digitone

[Spogg]

No, when I get interested in a challenge I follow my interest. I just can’t stop now!

The zip contains the two types of envelope generator which I believe operate like the modulating envelopes in the Elektone synth.
I’ve added relevant comments in the schematics. The envelope modules are stream-based so you could modulate/key-track the parameters should you wish to.

Fortunately I was able to address Martin’s excellent exponential envelopes “externally” with no changes to the ASM code. You’ll see the trickery involved!

I hope this is ok!

[k brown]

That's very cool - I noticed that the EG stages are listed as mod targets.

[Spogg]

I’m now puzzling over the HARM system.
I’ve read the relevant manual sections quite a few times and it’s still not clear to me. In the appendix they show 26 different waveforms, quite clearly made from additive synthesis. But I can’t work out what happens as you increase the parameter value. I know the waveforms are smoothly “morphed” from one to the next but what is the sequence?

I prefer the idea of having a start and end partial level array and morphing between the two under stream control. That way you can have any 2 waveforms. You could turn a saw into a square for example, or any other arrangement for start and end. Another idea is to set a single waveform and progressively decrease/increase the higher partials which would produce something akin to a filter sweep.

Whatever we settle on, as you say, it will have to have phase modulation of course. I’ll see what I can come up with…
----------------

EDIT:

I searched YouTube and found this tutorial:
https://www.youtube.com/watch?v=x2Ic9upij-U

At about 8:20 harmonics is demonstrated and in my view it was a bit disappointing based on my expectations. As you increase the HARM parameter it does go through all the waveforms in the manual. This is a set sequence so any sound using modulation of the harmonics table will tend to sound rather similar in terms of timbre change. Something else I noticed is that the fundamental sinewave is very dominant when harmonics are added. In the manual they show a “bell” waveform but a typical bell sound is dominated by F2 and F3 with very low F1 levels.

I think we can actually do better!

[k brown]

Martin's Spread Partials osc also has that sine-dominated quality at all harmonics settings; but might be an asset in an FM synth, but alas, that osc has no phase input.

Looking at the vid, it looks like those waveforms could be gotten by just a 3-way cross fade between 3 modulators: one at 1:1 Ratio, one at 2:1 Ratio and one at 3:1 Ratio. So each Op that the Harm control affects would have three 'hidden' modulators.

Of course, for the soft saw shape, the Op could just modulate itself at a low level, so only two 'hidden modulators' would be needed.

[Spogg]

Very interesting idea Kevin; use FM to create the harmonic changes.
Of course we would move away from the original, but that may not be a bad thing.

Experiments will now take place…

[Spogg]

Kevin, I tried out your idea of using FM for making harmonics and it’s brilliant! The range of timbres you can get is remarkable and I seriously think it’s much better than the Digitone’s HARM function, now I’ve actually heard it on the YouTube video.

I used a 4-way crossfade from sine waves F1 to F4 and set it up for demo so you can send it for FM to a modulator and carrier with separate level controls. If you add FM to the harmonics generator you get even more variety. It’s SO versatile, even with just 2 operators set as mod and carrier. In the demo configuration you don’t really need operator feedback because it can come from the HARM generator (it has an F1 osc you see) but you might like to use it differently of course.

I’m so impressed with the results of your idea that I have no incentive to pursue my other HARM ideas which would have added a lot of complexity to operation and, especially, CPU usage. At present the CPU is really low.

Now I have to eat my words.
I added the stepping ratios thing and I think it’s great in practice. One knob to scan through a huge range of timbres and it feels intuitive with immediate feedback due to the repeating iteration of higher ratios. Turns out the designers did really well and came up with something I would never have thought of.

So I think that’s me done for now, but don’t hesitate if you need any more input from me.
I had fun!

[k brown]

That's great to hear; can't wait to try it out!

My friend, you've ticked every 'mystery box' for this. Now my head will stop bleeding from scratching it so hard.
I think this will be a very enjoyable FM instrument to use, as Elektron intended the Digitone to be. This, of course will be even more fun because - no menus, and knob-per-function all visible at once. Leaning toward a GUI like 'Triple Paddy', with sliders like those on 'CSOh1' for the FM engine controls.

A thousand thanks once again for your invaluable assistance - another 'Powered by Quilcom' is on it's way!

[Spogg]

Like I said, I had a lot of fun and interest from this.

I’ve had a taste of possibilities from that last demo setup and I’m really looking forward to hearing the full thing…

[k brown]

OK, you knew I wasn't going to able to let your generous contributions just sit there in a folder, didn't you?

AND you knew I would return with hat in hand, didn't you?

The other major items I didn't realize I had no clue how to do are the 'non-standard' LFO modes; I got the Free-run opton there, but the other modes - I have no idea. I can't even understand what the Hold mode does; the text is very unclear and the diagram isn't much help. The One and Half modes I understand what they do, just not how to implement them. The Half mode appears to be a 'one-shot' mode, so Speed has no effect?

Does anyone know of modulate-able first order filters? The ones I use are the only ones I've seen and are controlled with greens.

It's also very unclear to me what the distinction is between the various Ratio and Pitch mod destinations are. I guess the Ratio mods are stepped in the same increments as the Ratio controls, so would 'zipper' like crazy? - how would the Ratios be made modulate-able, since they are in green?

I've kept things pretty much as they are in Digitone; I've found most of the limitations more fun than frustrating. The only real change I made is giving the Harmonics control an added Strength control.

The manual has a lot of frustrating omissions regarding control ranges, etc ('0-127' doesn't help much).

I'd kind of like to make this a stereo instrument, but that would require doubling the Filters, and not sure how much CPU that would eat up.

Thanks tons for the huge kick-start you've given this - and if Adam ever checks in on this thread, thanks again for your generous permission to loosely base the GUI for Triple Paddy on 'Viper'; I've adapted it for use on FlowTone as well.

[Spogg]

I’m a bad influence aren’t I?

I’ll have a look at this later and read up on the stuff you mentioned.

In the meantime I’ve attached Martin’s excellent 1 pole filter collection which includes green and poly types for modulation. I make a lot of use of these and I’m always eternally grateful for all the brilliant stuff he’s made and shared.