Choosing an 808
Listen for three things: the attack, the length and the tone. A clean, sine-like 808 leaves room for vocals and melodic parts; a distorted one fills a sparse beat on its own. Long 808s suit slow trap at 130 to 150 BPM, where notes ring for half a bar; shorter ones suit drill and faster patterns with lots of slides.
Keeping it in tune
Because an 808 is a note, it has to match your track’s key. Load it into a sampler, set the root note, and play the bassline from the keyboard. If the key is not shown, tune it by ear against a piano: a wrong 808 makes the whole low end feel muddy.
Many 808s in packs and archives are labelled royalty free; others are Creative Commons with a credit line. The badge on each card tells you which, so the sample you build your beat around won’t block the release.