Like Paternguy said, there is no need for a regulator (unless you use 2-cell lipo packs). When you take the 6v packs fresh of the charger they can have a peak voltage that could cause some servos to jitter. But, both NiCad and NiMH cells discharge that peak voltage extremely fast and will settle down to a safe voltage within several minutes. If you're worried about it you can wiggle your sticks around for a minute before flying to burn off that short-lived peak voltage.