when i was boxing i found the only thing i really needed for ahnd speed was to hit the heavey bag with 16oz's then go back to bag gloves and just do say 5 2's on 16 oz's then 2 2's on the bag gloves and that helped me pick up alot of speed. speed ball to me is a load of shit, i find the floor to celling to be much better for speed and acuracy assuming that the ball on the floor to celling is of a smaller size than normal.
So-called "Speedbags" are actually more about Timing than about Speed . they really should be called Rythym Bags . Yes , theyre are Faster and Slower tempos , granted , but its more about Rythym .
What you need to do is work your fast twitch muscle fiber for muscle quickness.
Fast repetition i.e. Push-Ups pushing your upper body off the ground and clapping or touching hands before landing again to do another repetition seems to work for building up your fast twitch muscle fiber. Also check the site below that I have listed. Practice and Train. Good Luck.