Phranzdan posted:All of the modern transformers are using some type of Thyristor voltage control. Depending on the setting and particularly at the lower voltage setting, when only a small part of the sine wave is being applied to the circuit, the waveshape looks similar to a spike.
Au Contraire, the MTH Z-4000 uses FET outputs to create a pseudo-sine wave, and it doesn't generate a sawtooth waveform.