| EMGs have blade magnets, so there shouldn't be a problem with string spacing or the string sitting between the magnets.
Therefore EMG 40DC's can absolutely be used on 4 string basses. It's been done before, by Ibanez for example. The BTB 700DX and the BTB 705DX both have EMG 40DC stock pickups, one being a 4 stringer, the other being a 5 stringer. | 
