Complimentary EQ TIP

Nice tip. Thanks for sharing!

Fender's original bass amps, the open-backed Bassman combos nowadays loved by many guitarists but not many bass players, couldn't put out the fundamentals of the bottom octave of a bass at much volume at all.

Nor can most common "hi-fi" speakers, which typically start to roll-off at around 100 or even 200Hz

They do however put out the harmonics, with the result our brains fill in the missing fundamental pitches like they do when hearing just the third and fifth of a major or minor triad, a trick used by jazz guitarists quite a lot.

Strange and complicated things, psychoacoustics.

I've never understood when people talk about boosting the fundamental of an instrument. Surely that fundamental changes with every different note. I might play within a range of two or three octaves on guitar. That's a three octave range of fundamentals.

But as far as how I would mix it in a track is, I would look or the main fundamentals of the source and use that to mix and keep that in spot, and let the performance jump in octaves beautifully, but still having the root fundamental. But If you play constant octaves in each verse, bridge, chorus etc.. for example , I would approach differently in adjusting each part..   Hope that  helps .