I play straight thru a 15 inch combo amp no effects,and play in a classic rock cover band.What is the best settings to get that Sabbath and early Ozzy sound.
You'll probably want some type of a drive pedal, unless you're able to get your combo to overdrive well. I'm totally in love with the Pigtronix Disnortion, which has both overdrive and fuzz section. That wouldn't be a bad way to go for you.
I use a Tech 21 sansamp Bass DI to get that tube amp growl. The newer VT bass pedal might work better at that but I also use mine as a DI to the sound board. Got to the tech 21 page and the have some sound clips of some different settings and see if they have the sound you're looking for.