The EP-3 series is designed to work in small rooms without a subwoofer or larger rooms with a subwoofer. They can go closer to the rear wall, at 2 feet, than the other open baffle models that need 3 feet. They feature the exact same technology as the EP4 and EP2 models just without bass drivers. Our new Polyester tweeter in the EP-3.4 is a major step up over the older Titanium compression tweeter from the EP-3. The 3 series are the only speakers to come with our DSP2.4 electronic crossover as they are designed to run with a subwoofer. With a subwoofer they can fill any size room with dynamic full range sonics. In a small room they go to 48Hz without a sub. Run without a sub we call them mini monitors on steroids as they image like great small monitor speakers with amazing dynamics. The step up EP3.8 uses our new Carbon Fiber 12" custom midrange, mated to our top of the line Neo Poly Tweeter with a step up crossover. It is wired with Wireworld OCC cable. If offers amazing speed from bass to treble with superb imaging and dynamics and an even more real "you are there" presentation.