A cathode ray tube has an electron gun oriented along an axis (Z), comprising a quadrupolar device which comprises three electrodes (5, 6, 7). Each electrode possesses a central aperture, a right lateral aperture and a left lateral aperture all three substantially rectangular. The centers (c5.1, c7.1) of the central apertures of the three electrodes are aligned along the axis (Z) of the gun. The centers (c6.1, c6.3) of the left and right lateral apertures of the second electrode (6) are situated along respectively a first axis (z1) and a second axis (z3) that are parallel to the axis (Z) of the gun. The centers (c5.1, c7.1) of the left and right lateral apertures (5.1, 5.3, 7.1, 7.3) of the first and/or of the third electrode (5,7) are offset with respect to the axes (z1, z3) passing through the centers of the apertures of the second electrode. Such an arrangement makes it possible to correct the MODEC defects.