I,ve now ported my alternative firmware YAM (Yet Another Mutation) originally developed for Shruthi to Ambika.
The latest source code and README is available on GitHub . Here’s the status of the firmware when I post this:
- PolyBlep implementations replace the original band-limited ‘saw’ and ‘square’ oscillators for higher fidelity and less memory footprint (Polyblep implementation inspired by, but less general than, Oliviers prototype for STM). For ‘square’ this primarily mean that the oscillator now have a more proper sounding PWM, i.e. more edginess, and no loudness drop for PWM modulation parameter above 0. For ‘saw’ there is no gentle high pass pre-filtering and the modulation is different. The parameter for saw now add mix of a 2nd saw edge, resulting in a saw with sub oscillator (actually super oscillator) sound.
- Triangle oscillator (‘triangle’) is no longer band-limited (to reduce memory footprint) and is folded (instead of clipped) upon modulation.
- Added a quad PWM oscillator (‘qpwm’) very similar to the quad saw (‘pad’). The modulation parameter simultaneously affects both detuning of the four pwm oscillators and the pulse width.
- Added an alternative FM oscillator (‘fmfb’) with feedback modulation. Just as for the regular FM oscillator, the modulation parameter defines the FM amount, but for modulation values above 64 increasing amount of feedback is added. At moderate levels the feedback adds ‘grit’. At higher settings it adds digital distortion (deliberately left in).
NOTES ON PATCH (PROGRAM) COMPATIBILITY with official Ambika firmware:
Due to qualitative differences of the ‘saw’ and ‘square’ oscillators etc, levels may have to be adjusted somewhat to mimic original patches. If you really miss the original saw oscillator from the official firmware, this one is still available as ‘oldsaw’ (it’s high-pass sampled and have a different character).
I’ve attached built binaries that can be used to update the firmware using the instructions in the manual BUT DO SO AT YOUR OWN RISK!
EDIT: deleted attached firmware file. See an updated README on GitHub, and later firmware builds later in this thread.