Change the BPM with the Pads Only! | SP404 MK2 Quick Tip
If you want exact control over the BPM of a specific pad, use this tip.
This beats scrolling the ENTER knob until you come to the BPM you were looking for. Now use the 1-10 pads (10 is acting as Zero), and type in your desired BPM after you activate the buttons in this tip.
You can gain even finer control in the PITCH/SPEED parameters page with the fine manual tempo control. But this tip works best for large changes in BPM on the fly.