MusicTechHelpGuy shows a quick but essential step when browsing bass loops in Logic Pro's loop browser: filtering by minor scale so only relevant loops show up.
Loops get auto-transposed to match your project key, but the loop browser lets you toggle between hearing a loop in the project key or its original recorded key. This matters because a loop that sounds right transposed might sound off in its native key, or vice versa.
He demonstrates this with an E flat minor loop being pulled into an E minor project, comparing the transposed version against the original half-step-down version before deciding it works better in the project key.
Not every loop that fits your key will fit your track. He tries one bass loop that clashes with the arrangement and swaps it for another that locks in immediately, a reminder to keep auditioning rather than settling on the first match.