If you place sub 1/7th of each dimension into the room and place near the listening position on an isolation platform, you'll be within the wave launch of the low frequencies and the direction of those notes will be perceived as coming from the mains sprakers that are producing the harmonics that are directional. The 1/7 puts the sub in the spot that's least suseptable to room harmonicas at low frequencies.
Subwoofer Question
Could having just one subwoofer (REL T/7x)with the crossover set around 60hz pull my image to the side that the sub is on?