Abstract: A bass reflex loudspeaker system capable of optimized sub-bass (<100 Hz) response. The loudspeaker system incorporates a closed cabinet, an electromechanical driver, a virtual acoustic radial transmission line (VARTL), a reactive alternate density transmission medium (ADTM) load and a radial right angle wave guide (RRAWG). The VARTL is disposed around and in front of the cone of the driver so as to allow the driver to maintain loading to very low frequencies, while simultaneously isolating the driver from reflected signals, acoustic summation or stimulus. The ADTM slows the speed of the wave, thereby causing delay and intentional attenuation of the initial waveform while, by way of radial expansion, allows the proper exit velocity. The RRAWG acts as a guide and is disposed within the VARTL to introduce the signal into the throat of the VARTL, thereby allowing the cone to drive the port air mass and the VARTL air mass with essentially equal pressure on each cycle throughout the frequency range of the VARTL.