An important class of dual-delay feedback systems of open-loop transfer functionG(s)=kexp (–Xs)/{1 –exp ( –Ws)} is shown to be unstable if ratioX/Win noninteger. By means ofz-transform techniques, it is shown that, by using a feedback transducer that senses over a substantial distance either side of its central axis, closed-loop stability may be restored. Such transducers, here termed ‘wide-beam sensors’, include transmission, backscatter and natural radiation types, as well as electromechanical conveyor-belt weighers etc. The paper demonstrates that designing transducers for very narrow beams may not be desirable from the overall system viewpoint.