Where should my thumb be gripping when playing A shape barre-chords?

Question

I've been reading about thumb aches while playing barre-chords, and apparently my thumb applies too much pressure, which is bad. Anyway, I kind of figured out how to relax my thumb and my hand. But I'm having hard times on chords that don't require barring the E string, especially those with A shape (B, C, C#, D) I try to free my thumb but it's impossible because otherwise I cannot ring all the string properly.

While doing a barre like G I can properly ring all the strings while my thumb is mid-width of the guitar neck facing the headstock, but on the chords I mentioned it seems really hard.

Answer 1

There's nothing wrong with barring all the strings on an A shape chord. In fact, there's nothing wrong with playing all six strings. It just gives the 2nd inversion of the chord, which can sound just as good in some songs.

You could consider playing strings 2,3 and 4 in different ways. The most common is with 3 fingers, obviously middle, ring and pinky. Try instead using middle and ring over the 3 strings. At some point higher up the neck, try using one finger on all 3, I tend to use ring.

All this will vary where the thumb is at the back of the neck, but instead of using your thumb as a vice, try to balance the pull of your hand/arm against the pull on the guitar body. You may well find that you hardly have to squeeze your fretting hand at all. Similar questions to this have cropped up on this site already. Sorry I can't locate them.

If you really need a thumb position, it'll be right in the centre of the neck, at the back.

Answer 2

If your guitar has a fat/wide neck, you can try to position your thumb parallel to where your index finger is when barring. Make sure it's flat against the neck, with mostly the force on the joint of your thumb.

You can also try changing to lighter string gauges and making sure your guitar has proper setup and action.