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.
You can download the Logic X project for free and use this sound in your own projects.