Ok, time to get this thread moving in the right direction.
The best mid bass slam woofer (Used to be) a jbl 2242 18 inch sound reinforcement woofer. They handle 800 watts and are meant to take live abuse from bands. Build yourself small box (Not necessarily 4 cubic feet) and enjoy. These will trounce handily 99 percent of other subs you guys are talking about. Light weight and efficient all in 1 package as they are made for this and 50 hz to 200 should be taken care of with ease. You won't regret this choice.
Use some 18 inch tc sounds lms ultra type equivalent to get your lower shake going on in 4+ cubic feet.
Throw in a Clone amp (Sanway fp14000) to handle the power needs and presto, you have way more low and mid bass than people who spend a insane amount on brand name gear costing a pretty penny.
Am i recommending low end gear... in a nut shell, no.... Tc sounds used to be one of the best but is now defunct so do your research to get something with 3 inches of movement or multiple cheap subs to make up the difference for your low end shake. Can't build boxes to save your life? Pay a local guy to do it for you.
Choose what color of wood you want in baltic birch stained to your liking. Build it like a tank and keep it for life. Build a triangle and throw it in an unused corner with 2 passive radiators top and bottom. Wife is happy, your grinning from ear to ear, and you have just learned how to not break the bank while being able to save up for that new avr, dyi sound group speakers, those new hypex amps, {
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Throw this with your speakers of choice and know you have spent your money wisely on quite honestly some of the best gear you will ever have for years to come. There is always bigger and better and maybe your a base junky and need more 18's or have a large room to fill. The sanway amp will handle it to a point or multiple less wattage subs to get you there.
If you have some update's to what could replace the Tc sounds subs, please step up and share with your fellow users. What is the best eq for the money for instance...
Don't be afraid to build some room treatments too as this will make your speakers and space sound vastly better. Cheers, everyone.