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 Kyma Forum
 Tips & Techniques
 Smart Harmonic EQ
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| Author | Topic: Smart Harmonic EQ |
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valentine Member |
posted 26 July 2001 12:05
 
Is there something in the Kyma library that could be used or modified in a way that when an audio signal is processed through an EQ, only the natural harmonic series of that note would be allowed through? So if middle C were played, then the filters would attempt to block all frequencies that are not in the harmonic series for that note. Is there anything close to this? Thanks, Bob IP: Logged |
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SSC Administrator |
posted 26 July 2001 17:20
You could try using a HarmonicResonator with the frequency set by the output of a FrequencyTracker. You may find some examples of using the output of the FrequencyTracker in the "Tempo, pitch, amp following" folder of the Kyma Sound Library. IP: Logged |
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pete Member |
posted 27 July 2001 06:40
Hi Bob By using a single delay with a delay period of 1/Freqency and no feedback , mixed with the original signal, you can make a comb filter with teeth (the zero volume points) that fit exatly between the harmonics, and the harmonics themselves are doubled in level. This means that sounds closer to the harmonics will still get through but a bit less . To make the filter stronger, (better at stopping the unwanted bits) you could have another delay fed from the first delay and mixed that in aswell. You could then do the same thing again and again to make it even stronger etc. Of cause every time you add a delay you have to attenuate the input by that number (i.e for 4 delays Attenuate 1/4) to avoid clipping. Another way would by to use one delay and add feedback. This would be like adding a long string of delays slightly less in volume every time. This gives you the problem of ringing i.e. if the feedback is too low then the filter wouldn't be that powerfull and if the feedback is increased and aproches a level of one ,it will be more powerfull but will start to ring. When the feedback = 1 the ringing will continue forever. This method is called a resonator. So wouldn't it be good if we could make a circuit that would do the same job as lots of delays without the feedback and excessive ringing, but only using a few delays. Well you can. There was one that I posted in the confabulation of this forum headed "What is this filter" which made just two delays to emulate as many as you wanted, but this is no good here, as you have to flush out the data every time you change the pitch, other wise you get a lot of very loud noise. But there is another alternative. as follows. If the pitch was 1khz then we put it through a delay of 1ms and mix that with the original signal. Then we take that mix and put that into another delay of 2ms and mix that with the first mix. Then we take that mix and put it through a third delay of 4ms and mix it in with the last mix . You can see that this has used only 3 delays but has given the effect of having 7 delays in a string. If you continue to add them in the same way , only 8 delays would make the same result as 255 delays in a string. Don't forget to attenuate by 1/2 at each stage or just attenuate the full amount before the first stage. If you need details as to what to put in the various fields to get it to work, let me know. Any noise type of sounds in your original signal will make it sound like a flanger but thats what this filter is. [This message has been edited by pete (edited 27 July 2001).] [This message has been edited by pete (edited 27 July 2001).] IP: Logged |
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valentine Member |
posted 28 July 2001 10:36
Thank you very much for the detailed information. I now have a very good place to start. IP: Logged |
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