What is Tight Bass?

the bass is stronger. maybe more sharp sounding. not sloppy. the opposite of that. clear and with nice resolution.

Here is the short answer, worth every minute of the hour and a half.

Keep in mind that many people prefer the general rumble, as in car radios and juke boxes.  Gives the sound a comfortable cushion and warmth that is pleasing to the ear. 

If you get the bass too tight, the music will sound too lean. 

Controlling the woofer after it has been put in motion by the signal. No extra bass caused by improper 'loose' movement after the signal.

i.e. My vintage 15" woofers, Electrovoice 15W's weigh 37 lbs each, very strong spider, rigid magnet enclosure, and a 5-1/4 lb Alnico Magnet to push/pull 'tightly' control the cone.

you could have an 18" woofer with a less strong spider and less powerful magnet, but longer throw, i.e. move more air, more bass (the iron law), but it would NOT be tight bass.

Somewhat anachronistic term for well damped, not ringy or boomy etc. Fairly intuitive. Nothing more than that. The bass player for Blood, Sweat & Tears described the Altec 421a as ’tight’ in an ad on the back cover of Guitar Player in 1969, e.g. I recall AR loudspeakers being described that way occasionally, as far as hi-fi goes.