For creating classic trap bass (808 bass) we will use ES2 synth from Logic Pro X. The main things in creating 808 bass are: sine wave + ADSR envelopes which will be generate the unique character of this type of sound.
We will start from a default ES2 settings but you can use another one
1. Turn off osc 2 & 3 in ES2 and choose a sine wave in osc 1. 2. Choose filter #2 in the filter section by moving the slider between filter 1 & 2. 3. In the router choose Pitch 123 (or Pitch 1) as the Target and choose Env 1 as the source.Move the modulation intensity slider to the max. level. 4. Adjust the decay in Envelope 1 5. Adjust the sustain time and level in Envelope 3. 6. Add some harmonics on your taste by Drive and Distortion parameters. 7. Final edits with EQ, Compressor and Multipressor.