yes, Gatemouth and Guitar Slim were famous for always playing with a capo for some reason. Slim was just very basic so I believe that's why he used one. Duke

Well, I know that it's sort of esoteric.  But while you can play all  the same notes in standard tuning, I find that these unique tunings sort of fit the thinking of the player.  In other words, having all your open strings notes in the blues scale I think influences they way one would think about soloing.  There will always be choices that are affected by that.  And individualized open tunings are frequently a choice of guitarists who are trying to develop something unique and different in terms of style.  More common in the older acoustic blues world,  But I think I saw an interview with him and he said he first got the idea to use a capo from Clarence "Gatemouth" Brown, and he  said - you are using a "choker."  He said he never used one until then, and eventually he never played without it.

Hi Vinny, Thanks for clarifying that about Albert's tuning. Duke

Looking at this a little more closely, the D minor uses an F instead of an F# (open D) on the third string, which is in the D blues scale; f# isn't.  One advantage to this type of tuning is that you have a very linear blues scale pattern, and can traverse over two octaves within five frets.  And on five of these strings your scale notes are 0,2,3,5 I think right across.  So it works very well for slide but also is very compact.  He also had some very unique shuffles which are a lot easier in this type of open tuning.

Great lesson.  There is some controversy about his tuning, some say F minor capoed on 5th or 6th fret, but most commonly you will see him capoed on 7th fret, playing in A in an open D minor tuning.  You can see him playing in D capoed on the 9th fret, and that would be I think an open F tuning.  But the F minor tuning is exactly the same intervals as open D minor tuning or E minor tuning.   So you would have advantage of all those great boxes used in open D and open E, which are the favorites of slide players.  It's similar to open G and open A, the intervals are the same, the forms are the same the boxes are the same.  So he was changing the root and the capo position to play in different keys, without changing any forms or riffs fingering wise, in relation to the capo. Of course, very unusual to use an open minor but definitely worked for him.  And of course there are advantages to having three open string roots, which is why that pattern of intervals has such a strong presence in  blues in general.

I couldn't retune obviously in the middle of the song seeing it's all live. I have never tried to learn to play in Albert's tuning. Don't see the point really, unless you were to make that your standard tuning. I play many times with Albert and he was one of the best and a great guy.