Here is another solfeggio drone.  There are many combinations to explore. This one has 741, 417, and 82 Hz.  These are approximate frequencies.

I keep using the same patch that runs two VCOs through two sawtooth animators and pulse width modulators into the MOTM-480 filters.  One of the frequencies is also divided by some integer and passed through a MOTM-440 VCF.  Slow LFOs modulate the pulse widths and the three filter cutoff frequencies.   Each waveform animator uses four LFOs internally.

When I listen to this on speakers there seem to be standing waves, so that as you move about the room it sounds different depending on where you are.