Tweeter placement

your question reminded me the Dynaudio Consequence.

The whole "tweeter at ear level" thing is overblown. Just sit at a height where it A: Sounds good to you and, B: Presents a deep and largely horizontal soundstage. This is speaker dependent. I sit with my ears a good 12-20 inches above the tweeters in a near field arrangement and everything's splendid.
It's possible those designers are placing the tweeter underneath the woofer to provide a warmer and more coherent sound when listening on-axis, with the woofer at ear level.

4-17-15: Uberdine
The whole "tweeter at ear level" thing is overblown.

I don't think it is. There are some very good reasons to have
the tweeter at slightly below ear level.

I sit with my ears a good 12-20 inches above the
tweeters in a near field arrangement and everything's splendid.

very interesting indeed! I think that I have heard this almost
never. The "almost" was the keyword - I've had the same
experience in one of my setups where the speaker is a Tannoy with a
concentric driver & these particular Tannoy drivers are known to have a 90
degree dispersion so vertical dispersion is very good. Sitting above the
concentric driver does not seem to have any sonic demerits. You don't state
which speakers you have but for your specific speakers your sitting position
might be the best one....

It's possible those designers are placing the tweeter
underneath the woofer to provide a warmer and more coherent sound when
listening on-axis, with the woofer at ear level.
Uberdine

you might be onto something here - i don't
think its done for "warmer" sound per se but i believe it's done for
more coherent sound.
The acoustical center of the tweeter is in front of the vertical plane of the
driver & the acoustical center of the bass driver is at (or maybe even behind?)
its vertical plane. So, sound from the tweeter will reach your ear faster than
the sound from the bass driver (unless you have a sloped baffle &/or do some
tricks in the x-over to delay the signal to the tweeter). So, if you have the
tweeter below the bass, the distance to the ear from the tweeter to the ear is
longer than the bass driver to the ear & this compensates for the different
locations of the acoustical centers of these 2 drivers. I.E. it time-aligns the
tweeter & the bass drivers.
yeah, Imhifiman, I remember a Dynaudio speaker that did this - it was the
Dynaudio Confidence 5

i agree with uber. Ear level with direct exposure may or may not be best. It all depends. Set it up whatever way sounds best. Forget about any audiophile dogma. The best tweak is usually the ones that are homegrown. It's the great equalizer and helps keep one of the audiophile merry go round. Think out of the box as needed and live happily ever after.

One rule to obey is to avoid early reflections that smear the sound. Too close to walls floor ceiling is all not good. Most tweets are all directional to some degree. So it's the reflections from room boundaries in the path of the sound wave that matters most. Ear level is just one option that delivers the most high frequencies to your ears which may or may not be a good thing. It all depends.