How to avoid aliasing? + morphing oscillators

Hi,

I want to make an morphing oscillator which doesn't just mix tri~, saw~ and rect~ together. Right now, I am using clip~ and some math to morph from tri~ and saw~ to some sort of rectangle and pulse. The problem is that I think this thing has some aliasing-problems. Here is a little Demo. You can see what's happening at ~17Hz.

Question: How can I prevent this from happening? I read that oversampling could work but I am not sure about this. (And I don't know how to do this with max. ;D) Is there an other way to develop a morphing oscillator like for example moog snyth have?

Thanks!