If you want to improve the performance of your Dunlavy's, rig up and secure as large as possible of a flat piece of wood on top of your speaker. This will increase bass coupling and improve loading into the room. You can vary the size, placement and amount of overhang in front of the cabinet to vary the amount of loading that you want and / or best suits your room.
The Dunlavy design is excellent, but one of the major variables that he couldn't control was the top woofer to ceiling distance. Using this approach, you've taken that factor out of the equation and can fine tune for best results.
Some may find that this somewhat limits vertical dispersion, but these speakers already have limited vertical dispersion as it is due to their design. If this is a concern, rather than use a flat baffle on top of the speaker, angle the board up and out from the baffle. This will still allow complete vertical dispersion into the room while offering improved bass reinforcement and better room loading than in stock form. This is kind of like using an angled "baffle extension" or "woofer beard" below a stand mounted monitor, but in reverse fashion above the cabinet. Like the above, changing the surface area and angle of the baffle extension / sounding board will allow you to fine tune for optimum results.
Other than that, you need GOBS of power with these speakers for best results. Wide placement on the long wall with no to very little toe-in also works best. If passively bi-amping, most speakers will work best with identical amps running the high and low frequencies. If actively multi-amping with a versatile electronic crossover, different amps can be used to great effect so long as one is willing to tinker quite a bit. Sean
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