09-14-2018, 12:33 PM
Use Audacity on PC to create a silent track of 30 minutes, line them up in a playlist before the sub track so that the sub starts playing at about the time you want. That's it. You don't need a special app on your phone then. In regard to apps, Foobar works best for me on Android phones, but it's not the most intuitive one so you would really need to look into it a bit.
In theory, theory and practice are the same. In practice, they are not.
