A calculation of the electrostatic wave spectrum emitted by rippled, neutralized, magnetically focused cylindrical electron beams is presented. For this, the wave equation for the rippled beam (obtained in the local approximation) is solved by a resonant mode coupling procedure for the fast and slow waves coupling case. Both surface and volume space charge waves are considered. As a result we obtain the frequency bands in which unstable waves can occur as well as the corresponding growth rates. These results are relevant for laboratory experiments simulating the injection of electron beams under space like conditions as well as for active experiments with electron beams in space.