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 Forum index » Clavia Nord Modular » G2 Building Blocks
True anti-aliased oscillator synchronisation
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Tim Kleinert



Joined: Mar 12, 2004
Posts: 1148
Location: Zürich, Switzerland
Audio files: 7
G2 patch files: 236

PostPosted: Wed Mar 07, 2012 4:42 am    Post subject: True anti-aliased oscillator synchronisation
Subject description: Simultaneous multi-waveform design with accurate tuning
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Generating anti-aliased oscillator synchronisation has been one of the remaining unsolved G2 problems.

After coming up with anti-aliased user-definable waveforms yesterday, it was obvious that this would be in reach too. It's very expensive DSP-wise, but from now on, if you really need alias-free osc sync, here it is.

One of the reasons it is such a big patch is because I ran into a super-strange malfunction of the stock G2 oscillator modules, forcing me to go the DYI way. This however has the advantage that this design is able to produce sine, triangle, sawtooth and pulse simultaneously, mixable to taste.

The circuit has perfect tuning and tracking resolution too. 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.

The tracking of the sync sweep isn't truly exponential, because that would have compromised the resolution, resulting in "steppyness". I scaled it with a ShapeExp module though, and for almost all purposes this will do fine.

Again -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: Two newer versions below. Version 3 is the best.


AntiAliasSync_TK.pch2
 Description:
True anti-aliased oscillator synchronisation; simultaneous multi-waveform design with accurate tuning

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 Filename:  AntiAliasSync_TK.pch2
 Filesize:  3.02 KB
 Downloaded:  4212 Time(s)


Last edited by Tim Kleinert on Wed Mar 07, 2012 9:46 am; edited 1 time in total
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Tim Kleinert



Joined: Mar 12, 2004
Posts: 1148
Location: Zürich, Switzerland
Audio files: 7
G2 patch files: 236

PostPosted: Wed Mar 07, 2012 6:47 am    Post subject: Reply with quote  Mark this post and the followings unread

I noticed that the sync slave osc has "steppyness" when sweeping high detune ranges, due to the compromised resolution of the exponentiator/integrator design. (I thought I could get away with it this time. Embarassed)

Here's a second (a bit more expensive) solution with no such steppyness. The sweep range is not as high though.

In both designs, I sometimes hear little "clicks" when sweeping over specific regions more rapidly. Why this is, I really don't know. It annoys me though. Still not perfect. Damn.

At least the oscillator produces virtually no "bird tones" when swept high up into the stratosphere (which was the main objective).


AntiAliaSync2_TK.pch2
 Description:
True anti-aliased oscillator synchronisation; second version with improved sync osc sweep resolution

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 Filename:  AntiAliaSync2_TK.pch2
 Filesize:  3.25 KB
 Downloaded:  4202 Time(s)

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Tim Kleinert



Joined: Mar 12, 2004
Posts: 1148
Location: Zürich, Switzerland
Audio files: 7
G2 patch files: 236

PostPosted: Wed Mar 07, 2012 9:45 am    Post subject: Reply with quote  Mark this post and the followings unread

Shocked Weird, the strange bug in the G2 oscillator module has magically disappeared, enabling me to present the concept I originally had intended which uses a stock OscB module. Ghost in the machine...

This is quite a bit more efficient DSP-wise and sounds alot better too. Also, the sync sweep is wide and exponential. However, it doesn't provide multiple simultaneous waveforms anymore.

I consider this the best version.


AntiAliaSync3_TK.pch2
 Description:
True anti-aliased oscillator synchronisation; third version based on a OscB module; less DSP load and better sound but no simultaneous waveforms anymore. Best version.

Download
 Filename:  AntiAliaSync3_TK.pch2
 Filesize:  2.45 KB
 Downloaded:  4296 Time(s)

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dorremifasol



Joined: Sep 28, 2006
Posts: 814
Location: Barcelona, Spain
Audio files: 7
G2 patch files: 49

PostPosted: Tue Mar 13, 2012 7:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Again, this is ultra cool Very Happy thanks!

I'll test it all properly tonight at home with the real machine.

Now you could make up some juicy filters Rolling Eyes

_________________
Cheers,
Albert
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