What is Bm7b5 chord?
Bm7b5 chord, sometimes written as Bm7(b5) and also called Dm/B, can be used as a nice substitution for plain Dm in several keys. It’s also called a half-diminished chord. In musical literature, Bm7b5 name is used more often than Dm/B, but in this post I’ll use both.
In this chord, low B note adds nice jazzy quality to the harmony. It is useful as a substitution for the plain Dm chord in many kinds of Dm -> E or Dm->E7 progressions in key of C (Am) and embellishes your playing quite a bit. Let’s look what is it and when it makes sense to use it.
This is the second post in the series of articles about using simple jazzy chords in your repertoire for improving guitar arrangements of the folk and pop songs. You can find the earlier post about C9 chord use cases there.
The simplest form of the Bm7b5 chord derives from the plain simple Dm fingering in open position so-called ‘D-Shape’. Check the progression below. It begins from a traditional Dm, then adds F on the fourth string, then replaces F of the first string by B on the fifths string. Strings 1 and 6 are not played. The last chord in this sequence is the main hero of this post.
When to use it?
The first obvious use case for Bm7b5 (Dm/B) is to substitute Dm in progressions like Dm->Am. Dm sounds there for too long, it’s boring. Play Dm for a half of the initial fragment, then amend it with Dm/B (Bm7b5) on the second half. That way it sounds much better!
Now, let’s add a second simple case, when Dm/B is used to embellish standard Dm in the long running Dm->Dm/B->Am sequence. In the example below, the first two bars are almost the same as above. The next two bars demonstrate Dm replacement by Bm7b5 in progressions like Dm/B->E->Am. This kind of Dm/B embellishment and progression is quite useful in many ballad-style songs.
Another form of Bm7b5 aka Dm/B
Here is another useful but a slightly different form of the same Bm7b5 chord. Now it looks like a traditional D-shaped Dm with added B bass note on the fifth string. You should mute or skip the 4th string. Let’s play a short 2-chord tango intro. In this case, Bm7b5 leads the melody voicing from F to E on the first string:
A few more comments
A good feature of these two forms is that they are movable: they can be played anywhere on the fretboard. As soon as you play an A-shaped barre chord anywhere on the neck and want to play a D-shaped chord and then E-shaped one after it, you can replace a Dm-shaped chord with one or another Dm/B form. It’s quite inconvenient to play D-shaped chord with barre, so this /B trick can save your fingers from some sore.