Would you take a Ferrari off road? Do I need a subwoofer?

Subwoofers are not purely for volume, for the same reason we use a 4wd for off road, we use a Ferrari for a race track. These vehicles are designed for specific jobs, regardless of how much you spend on a Ferrari it will not match even the cheapest 4wd off road and vice versa.

We use tweeters for higher frequency because they are fast and responsive but certainly can not move enough to create bass, we use midrange speakers (sizes from 2 inch to 6 inch) to reproduce slightly lower frequencies, things like vocals and mid bass. These are larger to deal with longer / lower frequencies. But these are still not capable of doing low bass. 

This is where your subwoofer comes in, nothing will hit the lows like a decent subwoofer. It’s all about designating jobs.

Customer :- I don’t want to be heard from blocks away, so I don’t think I need a sub.

A sub is not just for volume, it is there to achieve an even frequency response.

A simple break it down:-

Treble – Tweeters (there are some wide band mids that do an ok job as well)

Midrange – 2 inch to 6 inch

Mid Bass – 6 inch to 8 inch

Bass – 8 inch to 15 inch.

Obviously this is a basic interpretation, there are premium products that do some exceptional things, but none can reproduce a flat 30 hz note from a 3 inch speaker. (Yes this includes a brand we don’t need to mention, hint :- famous for small speakers in homes)