I really love the sounds and gazillion options on this site here:
Really well curated, maintained and sufficiently nerdy (the site is run by a signal processing engineer) to make it interesting for us here, even though it isn’t strictly bass related (but you can find some good drones to play to as well).
These sounds have helped me keep focus (and my sanity) many times! It’s free, but I donate about bucks every six months or so (totally worth it).
Check, for example, “Implanted memories” (for you Blade Runner fans) or “Shiny crazy cluster” (for you Pink Floyd fans), or all the more classical ones (Japanese garden and so on).