  We report experimental and theoretical results on the conductive regime of
electroconvection in hybrid aligned nematics. The drifting oblique/normal rolls
below/above the Lifshitz frequency are observed at the onset of
electroconvection under a.c. voltage. The experimental data on the threshold
voltage, wavelength, oblique angle and drift period of the rolls as function of
a.c. frequency are in good agreement with the results of linear stability
analysis. The transition from drifting oblique rolls to abnormal rolls is found
below the Lifshitz frequency with increasing applied voltage.
