Why is the ii chord half-diminished in minor?

Because it is built on the 2nd degree of the natural minor scale. Stacking thirds from B in A minor gives B – D – F – A: a minor 3rd, a diminished 5th and a minor 7th. That is a m7b5 chord, also written Bø.

Where does the G# in E7 come from?

It is borrowed from the harmonic minor scale, which raises the 7th degree specifically so the V chord gets a leading tone. Without it you have Em7, and Em7 does not pull towards Am.

Can I just play A minor pentatonic over the whole thing?

Over Bm7b5 and Am, yes. Over E7 it will fight the chord, because A minor pentatonic contains G natural while E7 needs G#. Changing that one note is the entire difference between playing over the changes and playing around them.

The minor ii–V–i in A minor

Bm7b5 – E7 – Am is the minor-key counterpart of the ii–V–I. Two things change and both matter: the ii chord is half-diminished instead of minor 7, and the V chord borrows a note that is not in the key signature at all.

Bm7b5 | E7 | Am

Chord tones

Bm7b5B – D – F – A1 – b3 – b5 – b7
E7E – G# – B – D1 – 3 – 5 – b7
AmA – C – E1 – b3 – 5

Open in the improviser →

Connections: E7 → Am

E → Ecommon tone
G# → Ahalf step up
B → Chalf step up
D → Ewhole step up

Common tones: E

Why this works

A natural minor gives you Bm7b5 and Em7 - and Em7 has no leading tone, so it will not resolve. The fix that defines the whole sound of minor-key harmony is to raise the 7th degree: G becomes G#, which turns Em7 into E7. That G# is the leading tone, a half step below A, and it is the single note that makes the cadence land. Notice what the half-diminished chord contributes on the way there: its b5 is F, and F is the b9 of the E7 that follows - the darkness of the key is already present in the first chord. Between Bm7b5 and E7 almost nothing has to move; between E7 and Am, G# rises to A and D falls to C.

How to practice this

The whole exercise is about one note. Make G# a decision, not an accident.

Step by step

Loop Bm7b5 – E7 – Am, four beats each, around 90 BPM.
Play the E7 bar using only G# and D - the tritone. Let Am arrive without you playing anything on the downbeat.
Now resolve on the downbeat: G# up to A. Do this until it sounds inevitable rather than surprising.
Add F over Bm7b5 and follow it through the whole progression: F over Bm7b5, F as the b9 colour over E7, E over Am.
Only then improvise freely - and check that every E7 bar still contains a G#.

Practice this with real lessons

You are looking at the half-step resolutions between E7 and Am. These lessons work on exactly this kind of movement.

No lesson covers this exact context yet.

No lesson matches this exact context yet.

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Frequently asked questions

Why is the ii chord half-diminished in minor?: Because it is built on the 2nd degree of the natural minor scale. Stacking thirds from B in A minor gives B – D – F – A: a minor 3rd, a diminished 5th and a minor 7th. That is a m7b5 chord, also written Bø.
Where does the G# in E7 come from?: It is borrowed from the harmonic minor scale, which raises the 7th degree specifically so the V chord gets a leading tone. Without it you have Em7, and Em7 does not pull towards Am.
Can I just play A minor pentatonic over the whole thing?: Over Bm7b5 and Am, yes. Over E7 it will fight the chord, because A minor pentatonic contains G natural while E7 needs G#. Changing that one note is the entire difference between playing over the changes and playing around them.