Alesis ACTIVE M1 Quick Start Owner's Manual page 13

Speaker Height:
The ideal height for M1Active 520/620 speakers is so that the speaker is parallel
to the ground and that the midpoint of the woofer and tweeter is at ear-height.
The diagram below demonstrates the ideal placement height of the speakers
relative to the engineer. Notice that the engineer's ears are directly between the
woofer and tweeter.
Woofer/tweeter midpoint
If possible, use speaker stands and move the monitors off of your desk (or meter
bridge, if you are using a mixer). This usually results in better imaging since the
monitor is decoupled from your desk and there is less chance reflected sound
from the desk (or mixer) reaching your ears and smearing the imaging of your
studio monitors.
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