I like LFO's with variable shapes to them, and here's a little workaround to get something of the sort from the matrixbrute: if you set the lfo speed to one of the custom modulation destinations in the matrix, you can modulate the speed of the LFO, with the LFO itself, making it run through its wave cycle at a changing rate, distorting the shape of the lfo. You can get narrow pulse widths from the square wave, and variable up vs down times from the triangle wave, like the MS-20.
It isn't a totally ideal control, there is some weirdness at the extreme ends of the modulation amount, and changing the modulation amount (shape) changes the speed of the lfo dramatically- you kind of need to find the ahape you like, then dial in the speed. It also doesn't work with tempo sync, only the free running lfo.
As an alternatative, I tried modulating the phase control, on lfo 1, but it didn't work that great, and added some weird audio rate artifacts to the lfo, that creep into the audio you are modulating. It did kind of work, if you were mellow with the mod amount, but the lfo changing its own speed was sonically smoother.
