After 90 min: You can manually adjust the tempo of a song to match another by listening for beat alignment.
Mix Your First DJ Set in GarageBand
After 90 min: You can mix 3-4 songs together with beatmatching and smooth transitions using a DJ app.
What you need
The 90-Minute Plan
Beatmatching means playing two songs at the same tempo. BPM (beats per minute) is the speed. If song A is 120 BPM and song B is 124 BPM, you adjust song B down to 120. This is the core of DJing.
Open GarageBand. Import 4 songs into separate tracks. Use the tempo matcher to identify each song's BPM. Write these down. Line up the beats so they sync visually on the timeline.
Fade out song 1 while fading in song 2. Do this 8 times. The crossfade should last 10-15 seconds. Songs should blend seamlessly. This is the basic DJ transition. Master it.
Use GarageBand's EQ tool to adjust bass/mids/treble as you transition. Remove bass from the outgoing song while bringing bass into the incoming song. This creates a more professional sound.
Line up all 4 songs with proper beatmatching and crossfades. Hit record. Play the entire set from start to finish without stopping. Listen back. That's your first DJ set. Share it.
Professional DJs spend more time on beatmatching than anything else—tight beat alignment makes or breaks a set.
Keep Going
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After 90 min: You can play a complete recognizable song from start to finish on piano.
After 90 min: You can play the C major scale smoothly in both hands at 120 bpm without mistakes.
After 90 min: You can play the I-IV-V-I progression smoothly and use it to accompany simple melodies.