I use the word metal loosely because I'd say only about 50% of OM's output could really be classed as such.

I'm basically looking for stuff in a similar vein. More calmer, quiet, contemplative and meditative stuff. Not necessarily ambient. Anything with a heavy emphasis on bass would be great. I'm not really looking for screaming vocals, but neither do I want to go fully away from metal.

Flower Travellin' Band's Satori might be worth looking into. They're a Japanese heavy psych band from the early 70s that are on the archives. Most of their stuff is good to varying degrees, but Satori I think is their only album that has a similar "meditativeness" as Om, as well as basically being universally accepted as their best album..

I already suggested ZAUM in the doom genral rec thread.

ISON's 'Cosmic Drone' and METHADRONE's 'Sterility' seem like good albums too for someone in search of meditative droney music.

OM are essentialy the doom version of this in case you weren't aware of it.

Chrome Pineal by Ramesses. It's more like a worship satan kind of meditative sound though. Probably the only "calm" Ramesses song.