An electric arc welder having an inverter with a waveform generator that generates a welding waveform with a waveform period and a root mean square (RMS) level for maintaining a stable short welding arc based on at least a cored welding electrode. The electric arc welder having a circuit to adjust a wave balance of the welding waveform to maintain the stable short welding arc, where the wave balance is a ratio between a period of a positive portion of the welding waveform and the waveform period.