Well, the the difference between the Velodyne lines are in the quality of materials. Whether it is the driver or the electronics, your money is going somewhere. In general the higher up the line you go, the smaller the production runs, the higher the price. The trade off is quality of sound. +/-3 down to 20 Hz is no small feat. All the F series subs can do it, the bigger the box the louder it can go. All the F series have <1% THD as well thanks to the servo feedback. The fruits of all this is tight accurate bass. It is quite amazing to be able to hear changes in musical notes in the bottom octave at high volumes. Its a musical quality you will not get from the CHT models, though they will likely outgun the F series in maximum dBs which is great for home theater.