Does anybody know how much SPL increase I will get if I have a loudspeaker in free space that generates a certain SPL and then place that speaker in a waveguide? I will be using the same input power and the waveguide diameter is 6inches (& all signals will be low frequencies). Does anybody know the proper equation to solve this?
Complex issue. A waveguide increases the coupling between the diaphram and the air, making the tarnsfer more efficient. But it will also change the impedence of the driver, and this fact has to be taken into account when designing the crossover.