Its very difficult to define a sound such as bass, as it is such a subjective impression which is influenced my the room and positioning.
Put it this way, my sub seems to hit a lot of the more musical notes in a passage, i.e. they are more audible and easily identified.
However, from listening to one of the more popular capable subwoofers you hear on here, i.e. one which will go much deeper with more impact, the bass was not as prominent/ apparent at the higher bass frequencies. The bass was there, just seemed more cooler, cleaner. Yet where the scene/track dictated, the bass was thunderous and you had the sensation I truck just hit the side of the building. My sub couldnt do that.
I suppose trying to get a sub that does all things well is the key, and im still trying to achieve that, but I am happy with the sub I have for now.
As ive learnt over time, any sub's bass will sound different wherever it is placed in the room in relation to where you sit.
My advice would be to determine how much you want to spend + the size of yoor room = which sub is best for you.
Ask the more experienced members in the sub forum what is recommended for your budget.
Hope this helps
Edit: Just ask Cheryl to get you a Fathom (joke meant in good humour)
You really do need to Listen to these things to learn what You consider to be a ' Rich Bass ' ... which term means absolutely nothing out of the context in which the description was made. Consider that the reviewer may have been listening to Music ? in which case maybe he /she was referring to a particular album of the Paul Robeson ...
or ... you see what I mean ? And thats before ever we get to Surround Sound for Home Cinema.
'Rich Bass ' can only make sense when you know what the reviewer was referring to and are personally familiar with what it sounds like over a range of systems.
As for " Does it mean its loud and good for club and techno music? " Did the reviewer say that the particular sub that you were reading of was good for these things? You don't identify the sub, nor the reviewer nor yet what the reviewer was playing from or what to what kind of system the reviewer used that includes that .. comparative range ? ... of sub woofers.
'Loud ' is a reference to Volume not to sound. Subs produce low level Sound that you can FEEL in the pit of your stomuch and are often used to compensate for lack of bass in small surround sound speaker systems.
Evidently you believe that forum members are equipped with some sort of paranormal Powers.
Generally I would define "rich" bass as having a fairly flat frequency curve, which means all the finer details across the bass frequencies aren't obscured by a nasty peak(s).
So rather than having what's known as "one note bass", you have a smooth and detailed sound in which you can pick out the more subtle effects.
I wouldn't say it's anything to do with how loud the sub is and generally "rich" bass is the opposite of what subs used for club music are designed for. That's more about achieving high SPLs with high distortion.