When we compare models such as RW-1000, BGVP DX6, ISN RAMBO II, we notice that each of these lacks in the low end especially sub-bass.
Build, cable, diver specs on these models are good. But why we have a problem with bass? There are several reasons for this, and I will not talk about the MX500 and PK style of the shell but the different designs of shells used in these models
1. Open design at the front cover (Rambo II, Ourart ACG), like an rim of the wheel. 95% aerodynamics and 5% bass
2. Vents on the front side of the shell, just behind the driver are for tuning the mids. If they are not covered with tuning foam then the sound is hollow, and with foam, we can easily control the middle tones and even the bass (to a lesser extent). Most likely this simple method was used for tuning the bass on RW-1000 but this is not the right way.
3. Now let's look at models that have fair sub-bass quantity vs quality ratio. The first model is, of course, Smabat ST10. It has the same "front" vents for mids but there is also a "rear" vent for the bass. The transmission Line (TS) design here probably doesn't have much significance because we know that the length of this "LINE" should certainly be more than twice as long in this case. But what is significant here is that with the existence of a "rear" vent there is no build-up of pressure behind the diver, in other words, the goal is to equalize the pressure on both sides of the driver to create ideal conditions for sound reproduction.
Another model Is HE150Pro which has a more simplistic design, without any "front" vents, just one "rear" vent.
From this, we can only conclude that it is not necessary to invest in some complicated design when simple solutions can give the same or better result.
That is why the correct layout and position of the vents are of great importance, and not only for bass but for SQ in general
