Boundaries and Half-Space Radiation
Boundaries and proximity are the relevant points here. Subs on the floor are near the boundary that is the floor. Outdoors, subs can be moved away from that boundary by flying them.
The theoretical advantage of subs on the floor is that the boundary prevents energy loss into that hemisphere of space — hence the term half-space. A source against a boundary will measure 6dB higher than if the source is in open space.
Why the Audience Stays in Half-Space Either Way
Humans are hard to fly, so they are usually on the floor. At the operating frequencies of subwoofers, humans are effectively against that boundary, which puts us in half-space anyway. Whether a subwoofer is against the floor or flown, since the audience is usually on the floor, the difference to the audience is minimal.
Proximity: The Real Difference
What does make a difference is proximity. If someone is hearing subwoofers that are 8 feet away on the floor, the level at that distance will be higher than if the subwoofers were flown 30 feet away. To achieve the same level would require more SPL from the flown subwoofers — usually requiring more subwoofers.
The Myth of Subwoofer "Throw"
Flying subwoofers doesn't increase their "throw" — it decreases the relative difference between the levels at the front and the back of the listening area.
Let's say the front-row listener experiences 120dB at 8 feet from ground-stacked subs. The back row would likely experience 96dB. If the subs were flown and the front row experienced 120dB at 32 feet, the back row would experience 108dB. But achieving 120dB at 32 feet requires 18dB more output at the source — meaning you need significantly more gear.
Ceilings and Flown Subs: A Common Pitfall
A ceiling is also a boundary. Subs flown near — or not near enough — to a ceiling can seem worse than subs flown outdoors. The reflection from a ceiling presents as a polarity-inverted mirror source, potentially creating destructive interference at certain frequencies.
Which BASSBOSS Subs Can Be Flown?
The SSP118 and SSP218 are both equipped with fly-points. The VS21 is also equipped with fly-points and shares a dimension (36 inches) with the MFLA, so they can be flown together using optional linking hardware.
