Originally Posted by Burialist
............ So my question is, how can i adjust bass lines that i learned to any backing track if that is possible.
If your bass lines, licks, riffs are generic you can insert them so they do harmonize. More on harmonization follows. R-3-5-7 is a generic bass line for any maj7 chord. R-3-5-b7 is a generic bass line for any dominant seven chord. Place the R (root) note over a root note on your fretboard and let the box pattern dictate where the other notes you will need fall.
Major Scale Box.
G|---2---|-------|---3---|---4---| 1st string
If the bass line you learned harmonizes with the backing track it should sound good. Question being how do you get harmony? OK hang with me for awhile; Picture some piano sheet music. The piano player normally plays the treble clef with his right hand and produces the melody notes. His/her left hand is playing the bass clef and producing the bass notes or bass line that will harmonize with the melody notes. If the two do not harmonize they will not sound good together. Back to how do we get them to harmonize. If your bass line has some of the same notes being played in the melody those two lines will harmonize.
Now here is the good part. If the melody line and the bass line share just one note per bar
(measure) you harmonize that bar of music.
Using just root notes (the name of the chord) see if you can maintain a beat with just root notes. Root on the first beat, then when that is flowing do a root on the 1st beat and the 3rd beat. Then see if you can get four roots in as this is a 4/4 time backing track. http://www.youtube.com/watch?v=dvF-Natz-tM
See what you can do with this one. http://www.youtube.com/watch?v=iEw90Ui8enE
How do you know which drum loop is good for your bass lines ?
Short answer if the drum loop is just rhythm, i.e. no melody, all you need do is get a groove going with your bass line. Normally locking in on the kick drum or the high hat. I normally lock in on the kick drum with the music I play.
If the backing track has melody your bass line has to share some of the notes that are in the melody line. Having the chords shown in your backing track helps a bunch. Root on the 1st beat. Got room, root on the 1st and 3rd beat. Still got room the 8 is always safe R-5-8-5. Still have room the correct 3 and 7 can fill out a safe bass line.
Pull up some 12 bar blues backing tracks and see what you can do with a 12 bar blues progression. http://www.youtube.com/watch?v=19hPZOK-SRs
Kinda important that you can hear the chord changes. Keep listening till you can identify those changes. The order they fall in is very predictable, i.e. you can count on the changes happening like the following.
Key of A or the I7 IV7 V7 ---- A7, D7, E7 chords in this order:
12 bar blues in A
|E7///|D7///|A7///|E7///| and loop back to the top and start over again. The last four bars can be different if you are not looping, i.e. using the E7 as a dominant seven wanting to resolve to the A7 tonic. Not looping the last two bars would be A7///|A7///|| Don't let that throw you, just wanted you to know that the last four bars sometime are different. http://www.youtube.com/watch?v=dskqGNgHxJA