The problem is one in the same with volume: identical frequencies in the same week result in constructive interference leading to a louder tone, which drowns out the others. I need to set the gain such that the max for any one frequency is 0.1 per week.

I agree it could use some randomness. To maintain harmony, however, I've made each note a perfect 5th of eachother. Maybe I could adjust the ratio to make perfect Nths instead.