Abstract: A method of and a device for use in manufacturing a color display tube in which magnetic poles are provided in or around the neck (4) of the tube envelope (1) and around the paths of the electron beams (18, 19, 20) extending substantially parallel to the axis (8) of the tube, said magnetic poles generating a permanent multipole magnetic field for the correction of the convergence, color purity and frame defects of the color display tube. The magnetic poles are formed by magnetization of a configuration of a magnetizable material (15) which is provided around the paths of the electron beams (18, 19, 20), said configuration being magnetized by energizing a multipole coil unit (21-28) by means of a combination of currents (Ia-Ih) which generate a static multipole magnetic field and the magnetization is produced by means of a decaying alternating magnetic field which initially drives the magnetizable material on both sides of the hysteresis curve into saturation.