I have a laney lx35 which is fine for my use and i dont want to buy a new amp just for using at home but the speaker is cheap and tends to crackle a lot. I have also noticed that most other amps of this size have a 12" speaker. I am considering buying a cab for it that has a 12" speaker. At low volumes mine is fine but when turned up to about 4 it starts crackling. Do you think its worth it buying a cab or will it still crackle and pop with a better speaker?

Vintage les paul

Gone digital! NI audio 8 into guitar rig and ableton live!

I would spend money on a better amp. The noise could be a blown speaker...might not be. So spending the money on a cabinet could be a waste of money.
I do not know much about the Laney LX series and admittedly did not look it up but I would verify that it is the speaker that is producing the crackle and not something else. Otherwise, you could end up with 112 cab set up that still crackles. Maybe try replacing the speaker first, assuming you genuinely like the amp. If it is a tube amp, I would suspect a bad preamp tube before a speaker. If this is a solid state amp, I would suspect a bad insert jack or solder job before a speaker.