There is no specific information available about space to mount a TV speaker under a 77« display on this floor stand. The product data does not include details about clearance or speaker mounting space. For a 77» TV, typical clearance under the TV on stands can be limited, often around 2-3 inches, which may not comfortably fit a soundbar without obstructing the screen. It is advisable to check the exact measurements of the stand and the speaker height or consider alternative mounting options for the speaker.