whats confusing me is there seems to be 3 different types of the scale starting with the Diminished and then the Whole Diminished and then the Half Diminished......what i want to know is IF there is 3 different types which would be the best pick for thrash metal
There's really only two. When most people say "A Diminished," they mean the A whole diminished scale.

The whole/half diminished scale, or just the "whole diminished" scale, is made up of alternating whole steps and half steps. This makes it an eight note(nine with the octave) scale. 1, 2, b3, 4, b5, b6, 6, 7 or however you'd like to represent that.

The half/whole diminished scale, also the "half diminished" scale. It's like the whole diminished scale but the pattern is reversed, alternating half and whole steps. So you get 1, b2, b3, 3, b5, 5, 6, b7.

As for the best one... play and find out.
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