Yes indeed, some bass guitar cabinets do have tweeters. Sometimes the tweeter is one of those terrible piezo units that will add nothing to the music, but scythe your ears off if you get too close.
Sometimes, bass guitar cabinets are more sophisticated and approach the complexity of a full-range PA cabinet, perhaps though with the emphasis still on bass.
The thought is that if a full-range loudspeaker needs a tweeter, then maybe some of the harmonics of the bass will be lost if a tweeter is not provided.
OK, let's be clear... a bass guitar cabinet does NOT need a tweeter!
Can't get plainer than that. But why not? It's all about how the bass guitar tone is produced (and any guitar for that matter)...
The sound of the bass guitar is a combination of five things...
Oh yes, and the player (and the strings, and plectrum/fingers, fretted/fretless but I have to stop somewhere).
Of these, the pickups produce a very clean signal, rich in harmonics, from the strings. The amplifier will create an almost equally clean signal, but much higher in level. The amplifier can also enrich the harmonics through distortion when driven hard.
But it is the loudspeaker drive unit where the interesting things start to happen. The cone of the drive unit bends and produces even more distortion, but richer and more complex than the amplifier. And just because a drive unit is large doesn't mean it can't produce high frequencies - it just means that those high frequencies will be distorted...
Yummy! This is just what we want.
Yes, a 12-inch or 10-inch cone can produce all the high frequencies a bass guitarist could desire, and the low ones too. Being reasonable, it is not going to produce a lot of level at 20 kHz, but we are talking about bass guitar, are we not?
In my opinion, the provision of a separate high frequency drive unit on a bass cabinet is absolutely not warranted.
OK, just my opinion, and yes the number of times I've played bass on stage is in the hundreds.
Your opinion is welcome too...Come on the FREE COURSE TOUR