REAKTOR COMMUNITY

Cool As

thanks a lot, really good!!

nice and squelchy :-)

Cool.

@James ah i understand, thanks; btw it is not "hyperbolic arc tan" but "hyperbolic tan": tanh(x)=(e^(2x)-1)/(e^(2x)+1) see structure of tanh-module.

Herwig, a transconductance amp converts a voltage into a current, just like a resistor, but they usually have an adjustment input that can set the scale factor. In Reaktor you can implement them very simply just with a multiplier module. But most real-life transamps are nonlinear in that the effective (the scale factor)is not constant, but decreases as the input voltage gets away from zero.The input-output relationship is very well modeled as a hyperbolic arc tan function.

thanks! yes i see several sites about transconductance amps (google) but how can you translate it into reaktors core cell or dsp. Are there any links?

Jeremiah, the mx-20 filter is encapsulated in a core cell which can be found in the ensemble. Of course, part of the sound of the ensemble comes from the parallel ladder filter, so you might want to use that too. Herwig, the mx-20 filter is derived from the analog ms-20 schematics (available in many places). I converted it to a digital filter by replacing the resistor-capacitor combos with simple digital integrators. This does not give an accurate modeling of the ms-20 frequency response (better to use a bilinear transform approach for that), but is good enough for musical purposes. The distortion aspect of the ms-20 is modeled in two places - first the nonlinear characteristics of the resistors (usually implemented as transconductance amps) are modeled with one set of hyperbolic arc tan functions. The second place is the deliberate (in the ms-20) distortion caused by the output amp, which is modeled with another hyp arc tan. Finally resonance is modeled with simple feedback. There is a DC-blocking high pass in the resonance feedback. It adds a little bit to the sound and prevents some problems. The resonant frequency is not a linear function of the freq input. By my calculations, at zero resonance the cutoff freq is f/(1-f)(3-f), where f is the frequency input. Bad things happen when f is more than 1/3.

I'd like to see the filter by itself.. it's a great sounding filter that i would love to use with other synths.

Hi James, i want to add a comment and a question: I like the warm and smooth sound of your filter. It is a very musician filter. my question: I want to understand how you have build the filter. The structure is very difficult to understand. I see in your main structure three filters (two MS-20 filters in serie and a parallel ladder filter). The inner structure of the ms-20 filter seems to be a second order filter. Can you give more information about constructing? ciao herw

yes - thanks

yeh,a delicious filter...thx for sharing this kind of thing!

As you say, plain vanilla for the instrument concept, but the filter sounds brilliant, and is just waiting to be used elsewhere. James, your work always has bags of character, and doesn't sound like reaktor. Nice one! wuntun