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Tim Kleinert
Joined: Mar 12, 2004 Posts: 1148 Location: Zürich, Switzerland
Audio files: 7
G2 patch files: 236
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Posted: Wed Mar 07, 2012 4:41 am Post subject:
True anti-aliased user-definable waveform oscillator Subject description: Draw waveform of choice; accurate tuning |
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Generating anti-aliased user-definable waveforms has been one of the remaining unsolved G2 problems.
I solved it yesterday. It's quite expensive DSP-wise, but from now on, if you really need user-definable waveforms, they are available.
You can draw your waveform of choice into the 16 step control sequencer. You can use the XFade step interpolation or deactivate it -the algorithm has no problem with the steep waveform flanks. If, you by any chance, still bump into aliasing, try lowering the frequency of the 36dB anti-alias filter. I tried it under many conditions and it should work the way it is though.
Also, this is the first DIY oscillator with perfect accurate tuning. The only caveat is that the circuit doesn't like ultra-fast and wide pitch modulations. It will still work, but the anti-aliasing will be compromised.
Nothing this red box can't do.
cheers to all,
Tim
EDIT: Warning! This circuit pushes the limits hard, and can malfunction on the demo software under certain conditions. The G2 hardware has no problem though.
EDIT2: Optimised version lower in the thread.
Description: |
True anti-aliased user-definable waveform oscillator; Draw waveform of choice; accurate tuning |
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Download |
Filename: |
AntiAliasWave_TK.pch2 |
Filesize: |
2.55 KB |
Downloaded: |
4285 Time(s) |
Last edited by Tim Kleinert on Wed Apr 04, 2012 1:09 pm; edited 1 time in total |
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dorremifasol
Joined: Sep 28, 2006 Posts: 814 Location: Barcelona, Spain
Audio files: 7
G2 patch files: 49
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Posted: Tue Mar 13, 2012 7:09 am Post subject:
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Tim, this is incredible. Thank you very much!
This was my most wanted feature on the G2, because I love small waveforms (did a lot of these in my Game Boy game soundtracks). I don't think I'll ever understand how you did it, but thanks again _________________ Cheers,
Albert |
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Tim Kleinert
Joined: Mar 12, 2004 Posts: 1148 Location: Zürich, Switzerland
Audio files: 7
G2 patch files: 236
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Posted: Tue Mar 13, 2012 12:55 pm Post subject:
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You're welcome. Sorry it's so DSP-expensive. If you don't need accurate tuning and pitch resolution, it can be economized considerably.
Also, if you intend to use this polyphonically, you can save some DSP by putting the waveform generator in the FX area and piping the audio and readout pointer back to the VA area via interslot.
Combining both these optimisations, it actually becomes surprisingly cheap DSP-wise.
As to how it works: In a nutshell, I'm constantly re-generating the waveform in a DIY sample memory array and preemptively cutting off the frequencies that would bounce back from Nyquist (alias) when playing back the waveform data at the desired pitch. The result is a pretty decent sounding wavedraw oscillator. |
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dorremifasol
Joined: Sep 28, 2006 Posts: 814 Location: Barcelona, Spain
Audio files: 7
G2 patch files: 49
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Posted: Tue Mar 13, 2012 1:45 pm Post subject:
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No problems with the DSP usage, worths all of it. Thanks for the tips. I'm already having fun morphing between waveforms using the morphs and midi
Some time ago I tried to emulate the so called Vowel-Consonant Synthesis used in the Casio keyboards of the eighties (I have an MT-68 and a CT-410V), but with the aliasing it sounded too ugly. Then I tried your previous method without tuning accuracy, but then it didn't worked very well either. Now I will be able to do it _________________ Cheers,
Albert |
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xav
Joined: Mar 21, 2005 Posts: 164 Location: paris
Audio files: 8
G2 patch files: 7
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Posted: Wed Mar 21, 2012 5:01 am Post subject:
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Waw, Tim!
You are still giving us mor reasons to use that synth!
Thank you very much |
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Tim Kleinert
Joined: Mar 12, 2004 Posts: 1148 Location: Zürich, Switzerland
Audio files: 7
G2 patch files: 236
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dorremifasol
Joined: Sep 28, 2006 Posts: 814 Location: Barcelona, Spain
Audio files: 7
G2 patch files: 49
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Posted: Wed Apr 04, 2012 3:20 pm Post subject:
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Is there anything you can't do with this synth? _________________ Cheers,
Albert |
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Tim Kleinert
Joined: Mar 12, 2004 Posts: 1148 Location: Zürich, Switzerland
Audio files: 7
G2 patch files: 236
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Posted: Wed Apr 04, 2012 3:45 pm Post subject:
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dorremifasol wrote: | Is there anything you can't do with this synth? |
It doesn't do the dishes.
...Yet. |
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