Future requirements on higher beam intensity and brightness will need an upgrade of the present CERN accelerator chain. Linac4 will be an essential part of the upgrade of the proton accelerator facility. The source for this H(-) linac will be based on a copy of the DESY rf driven H(-) source. New possible radio frequency quadrupole alternatives (with different injection energies) and a pressing linac schedule made it necessary to develop a flexible two-source design.