The way I do it is:-
Turn all the oscillators and brute factor off
Adjust filter and resonance to get a clear tone
Now play 2 notes an octave apart and adjust ATT1 till the 2 tones are an octave apart, (a guitar tuner helps here) don't worry if they are not the notes your playing.
Now raise the volume of an oscillator and adjust the filter and tune it to match.
It won't be perfect but you'll have 1 octave pretty close, and of course 5 minutes later the temperature will of changed and you'll have to do it all again
P.S. Arturia on your next synth please add a tuner they are so helpful with analogues