FM modulation unwanted artifacts

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Father
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Joined: Thu Jan 09, 2014 5:48 pm

FM modulation unwanted artifacts

Post by Father »

How would you eliminate the noisy artifacts when doing a simple FM setup like the example?
Is this the right way to do it at all?
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Spogg
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Re: FM modulation unwanted artifacts

Post by Spogg »

Hi Father

I believe the noise is caused by wavetable switching inside the Prim. If you set the FM knob to a low value the noise goes. A set of wavetables is created by the Prim to limit bandwidth based on the base frequency selected for the note played. With a wide FM excursion in the Freq input the Prim will be selecting different tables rapidly.

The more usual approach is to modulate the phase. This means altering the readout rate from a single chosen table and the sound is the same but without wavetable switching.

I've Spogged your schematic: Changed the FM input to the Phase input and changed the FM knob to go between 0 and 1 and to my old Vulcan ears the result is good.

If I'm wrong about all this I'm sure someone will let us know!

Cheers

Spogg
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Father
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Re: FM modulation unwanted artifacts

Post by Father »

Aha didn't know that.
Yes sounds good enough i think, and its very similar to the old one which is good.
Thanks so much :)
Father
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Re: FM modulation unwanted artifacts

Post by Father »

Still happening, specially with different waveforms its more obvious and annoying.
Does this happen only with wavetables?
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martinvicanek
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Re: FM modulation unwanted artifacts

Post by martinvicanek »

Father
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Re: FM modulation unwanted artifacts

Post by Father »

martinvicanek wrote:It's a bug;

Oh man that's too bad. :|
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martinvicanek
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Re: FM modulation unwanted artifacts

Post by martinvicanek »

Not necessarily:
1. You can use algorithmic oscs that allow through zero FM
2. Now with the new 3.0.9 features we can build our own wave reader ;)
Father
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Re: FM modulation unwanted artifacts

Post by Father »

martinvicanek wrote:Not necessarily:
1. You can use algorithmic oscs that allow through zero FM
2. Now with the new 3.0.9 features we can build our own wave reader ;)

1. Not following you, a quick example would be great if you have the time.
2. Thats nice. Well have to upgrade for that.
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martinvicanek
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Re: FM modulation unwanted artifacts

Post by martinvicanek »

Father wrote:1. Not following you, a quick example would be great if you have the time.
Scroll down...
Father wrote:2. Thats nice. Well have to upgrade for that.
Not sure it is stable yet. :(
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Father
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Re: FM modulation unwanted artifacts

Post by Father »

Nice stuff. the polyBLEP Saw Osc sounds clean! (I think hehe). I just wish it was a wave table read :lol:
Any chance the bug gets fixed on next update?
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