Short Sawtooth Test on Elektron A4. Testcase: first Osc 1 with saw, level to 95, played from C-5 to C+5. Filter setting: filter 1 set to Cutoff 127, Reso: 74, Overdrive to 12 (to waveshape the Osc 1 waveform, which is oddly changing its waveshape from octave to octave) That´s how the sawtooth stays a sawtooth. Filter 1 is now almost lost as filter...but there is still filter 2. Filter 2 settings: Cutoff 63, Reso 0, Type LP2 (12db) Keytrack 0, Envelope Filter Depth 63 (i wanted to have the envelope opening the filter). Played again a few C notes from low to high. Then Filter 2 cutoff to 0 and again a few notes. voila, nice and round. The trick is here to use filter 1 and it´s overdrive as a waveshaper for the Oscillator. Oh and i added from time to time also Subosc, 1 octave below, from Oscillator 2, with Level 95 too. Makes it even rounder.