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 Stable Highpass filter?
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| Author | Topic: Stable Highpass filter? |
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patrik Member |
posted 19 October 2011 08:07
 
Hello! I have the feeling that the Highpass Filter Sound is especially unstable. If i feed it with the 1024saw sample in an oscillator sound, i seem to have to take care not to send it more than a level of 0.25, take care not to set a cutoff of 0 hz, and as usual the resonance is something to be handled with care, that's ok. But is there a stable highpass which just starts to ring at high resonance settings around somewhere? Is the highpass setting in the filter Sound actually just "Input minus lowpass filtered Input" or is it a different Algorithm? Thanks a lot! [This message has been edited by patrik (edited 19 October 2011).] IP: Logged |
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SSC Administrator |
posted 19 October 2011 10:58
quote: A different algorithm: the HighPassFilter is an IIR filter. (IIR filters include feedback, meaning that for some settings they can have infinite gain). For a synthetic waveform like sawtooth with unity gain, it's a good idea to attenuate the signal before passing through the HPF. You could also set the Scale of HPF to 0.5 and then add a Gain, AFTER the HPF to scale it back up to full amplitude. If the resonance seems to be different for different frequencies, you can use an into array in the Feedback field, for example, something like: !FreqCutoff into: #( {0@0} {100@1} {4000@0.5} {8000@0.25}) That was just an example to show the form of the expression, NOT the actual numbers you would use. IP: Logged |
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patrik Member |
posted 19 October 2011 23:35
would you agree that it would be nice to have a lowlevel and often used sound like this woriking without having to try out arrays of resonance multiplicators or different pre attenuation/postgain stages?  Sorry i really believe that this filter is in some aspect a very good one, but for my use in buiding synthesizers mainly, it simply has quite some disadvantages. So, some questions emerge/remain: 1. if attenuating, and boosting pre/post filter, don't i loose some Bits of information? I'm not too much into the mathematics here, but i use a factor of 4 for both usually, and it may occur that i use more of those filters serially. 2. Is there an alternative filter anywhere? i can't imagine i am the only one with the desire to obtain a "analogueish" highpass filter.. Everybody else using some "input minus VCF-sound" stuff?? Thanks a lot! Patrik IP: Logged |
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cebec Member |
posted 20 October 2011 08:06
I'm not in front of Kyma but the VCF only does Lowpass filtering? The Prototype Reference doesn't mention what type of filtering is available. I know it's Lowpass, certainly. I guess it should be called LP VCF, if so. IP: Logged |
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ChristianSchloesser Member |
posted 20 October 2011 20:08
quote: you are not alone ,-) actually i had the same problems as i started with my "analog emulations". I usually have to use many "workarounds" for creating "analog synth" type of sounds since the VCF-Prototype is only Lowpass(even the icon!). One feature requests is a nice sounding "Analog voltage-controlled-filter emulation" HighPass Filter Prototype! Maybe a diode-ring Sallen-Key filter emulation in kyma ;-) The one used in the Yamaha GX-1 is the one i am talking about: http://www.cs80.com/ne_proj.html I own two modified(CV+Inputs) SY1s ... and they sound so amazing! ... if there will be ever the possibility to write my own microsounds for the pacarana, then modeling the behavior of the two yamaha SY 1 filter circuits would be a great project!(also i have some other ideas too! ;-) all the best
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patrik Member |
posted 21 October 2011 03:09
quote: thanks! IP: Logged |
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