Organ effects rack

  • Austin Leeds

    Austin Leeds - 2011-03-16

    I've been using Rakarrack for several months now for my old tube-based Conn organ, and I've got to say, it's really amazing. I can pull off anything from a pipe organ to an overdriven "the beast" sound with Rakarrack, and I'm sure this is only the beginning of my learning with it.

    There are a few features I'd like to request, however:
    Slow attack (to augment the swell pedal)
    Multiple octave Octavator (to take an 8' stop down to a 16', 32' or even 64', or to raise an 8' to 4', 2', or 1')
    Portamento (just because I have an organ doesn't mean I don't feel like making it sound like a theremin some days ^_^)
    Oscilloscope (would be great to see how the effects are changing the wave)

    If there's any way an effect could be made that fundamentally changes a tone (for instance, from a sine wave to a square wave), that would be awesome too!

    Keep up the great work,

  • Transmogrifox

    Transmogrifox - 2011-03-16

    There is a scope as a sort of easter egg.  Click around near the top of the tuner, you'll find the scope.  There's also a spectrum analyzer hidden in there too.

    Slow attack can be accomplished with the Expander.  Set the attack time long, release short (typically short release is what you want).  I admit it is more of a side effect, and it is no substitute for a good triggered ADSR - I will probably add the ADSR at some point now that I have a descent beat detector working in the development repository.

    Portamento - Look at the Shifter effect in version 0.6.1 (I think it is also in 0.5.8).  Anyway, it's a triggered pitch bend.  Eventually we plan to add the reverse mode where it starts at the shifted pitch and seeks the real pitch more true to the portamento - it's a real quick and easy thing, so what your asking is not hard to do.

    The multiple octave octavator will take some effort, but I have been working on an interpolated delay line code block with pitch shifting in mind - it may use resampling instead of the FFT, which will probably be less processor intensive than what is currently used for pitch shifting.

    An effect that fundamentally changes a tone is called distortion.  There are several waveshaping functions in all the distortion, overdrive, derelict, etc.  Really the best place to do this kind of thing is within the synthesizer engine itself.  An effect to really do what the organ/synth does to change sine/saw/square on each tone requires breaking everything down into its respective bands then re-synthesizing the signal - that, then, would make Rakarrack a synthesizer ;)  Well, it isn't too far from what most synths do now - all we would need to do is add a few oscillator modules with MIDI input capability then you have a synthesizer.

    I'm glad you enjoy Rakarrack.  Keep tweaking - the possibilities are many ;)

  • Austin Leeds

    Austin Leeds - 2011-03-16

    Thanks for the quick reply!

    Can't find the scope, but I think the spectrum analyzer is located under the rack chooser thing (very knowledgeable, I know).
    I'll be sure to try the expanded ASAP, but I can't wait for the ADSR!
    The portamento sounds a little finicky/crippled, but I'll give it a shot.
    Multiple octave octavator, can't wait to see it. For some reason, the current one goes way out of tune on me after a a couple hours or so, so I have to restart the app.

    The organ puts out a sine and then filters it, from what I can see. Flute stops are pure sines, but when I overdrive them, I get close to triangles, I believe. I'll have to keep tweaking with it once I find the scope. My dream would be to pull off a Novachord-like sound, which might be possible with a little physical restoration and tweaking.

    I'm running a PIII 733 MHz coppermine with 1152 MB RAM and a 4.3 GB HD—with my iPad as a wireless monitor. Weirdest setup ever!

  • Austin Leeds

    Austin Leeds - 2011-03-16

    Aha, found the scope!

  • Transmogrifox

    Transmogrifox - 2011-03-18

    If you compile from source, update from recent git repository.  I added a mode for portamento in the Shifter effect.  It starts at the interval you define, then triggers on envelope exceeding a certain threshold and shifts down until it reaches the note you are playing.   You can set the attack & release times to set the rate.  It sounds really sweet on guitar.

    Right now it is a linear sweep, but I will add exponential sweep when I have more time. This mode required an addition of a whole 3 lines of code, so as you can imagine it only took me a few minutes :)

    Exponential sweep will require making the code a little more tidy, but the actual exponential part is easy :)



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