Zero Autoformers

About the Zero Autoformers

The Zero Autoformers by Paul Speltz are toroidal single-winding transformers that multiply the impedance of connected speakers, allowing an amplifier to see a higher impedance load. This is particularly beneficial for output transformerless (OTL) tube amplifiers, which perform better with speaker loads in the 8 to 16 ohm range. The Zero can transform a 4 ohm speaker into 8, 12, or 16 ohms depending on the tap used, improving amplifier control, power output, and sound quality. They help reduce current demand on the amplifier, resulting in cleaner bass, more precise spatial presentation, and enhanced overall musical refinement. The product is available in different models including the DIY-ZERO, ZERO-Box (housed in a wooden box with Cardas binding posts), and ZERO-Cables. The frequency response is reported from 2 Hz to 2 MHz, ensuring minimal interference with audible frequencies. Users report significant sonic improvements, especially with OTL amplifiers and speakers with low nominal impedance.