Dissonance is often seen as a negative, but it’s a bit like sourness in food: you might not want too much, but without it, we’d all be eating cottage cheese.
Here are four chords, all with at least one dissonant note.
As an alternative to C major, this adds the ninth (D) and the dissonant #11 (F#).
There are two dissonant notes in this E minor substitute. The F# (the ninth) is just a semitone away from the open G (minor third) and the C# (sixth) is a dissonant tritone from the open G.
Here, the dissonance is between the major seventh (A#) and the root. In most major 7 chord shapes, the major seventh is placed above the root, making a larger interval, but here we’re emphasising that dissonance.
4. Em add#11
Another Em substitute, but this one sounds much more menacing. You can hear this chord, with its clashing A# to B interval, in some of Buckethead’s more ambient work.