Minor 7th flat 5 seems to be another chord i do not understand.. if diminished chords are:

1-b3-b5

And the minor7th b5 is:

1-b3-b5-7

Why is it not DiminishedAdd7th or something more logical like that... is there some sorta rule that im missing when it comes to naming chords...cos i keep coming to some of these chords which have diffrent name to what they should have...

Aye just the system is a bit confusing

1-b3-b5 (diminished)

And the minor7th b5 is:

1-b3-b5-7 (which i personally would prefer to say diminished 7th) as it makes far more logical sense... sadly it doesn't in the fact that you got to go with what the majority would say. Otherwise useless in knowing the word of the chord.

Not sure why I'm writing this since the last post is almost a year old, but...

I believe that min7b5 is also known as a "half-diminished" with the common jazz symbol being a little circle with a slash mark through it. A dim 7 has a bb7 (a double flatted 7th, which is enharmonically the same interval as a 6th). So A-dim 7 (full-diminished) consists of A-C-Eb-Gb whereas a half-dim 7th has a regular b7 (A-C-Eb-G).

So... if the OP would prefer to name this chord a half-diminished (or half-dim 7th), he can do so without violating the sensibilities of the jazz purists.

Cheers,
Bert