Single grain Y1Ba2Cu3O7−x (YBCO) bulk superconductors were prepared from different starting precursors. In the first case, Y2Ba1Cu1O5 (Y211) powder as the solid phase and the liquid phase of mixture of YBa2Cu3O7−x+BaCuO2+CuO powders were used. In the second case, the solid phase was prepared from the mixture of Y2O3+BaCuO2 instead of the conventionally used Y211, and as the liquid phase a mixture of Y2O3+BaCuO2+CuO powders was used. The trapped field measurements at 77 K were performed and microstructure of samples was studied by polarized light microscopy. The positive influence of Y2O3+BaCuO2 starting precursor on the oxygenation, Y211 particle refinement and measured trapped field is shown.