Step-Up Transformer Calculator

What it does. Suggests a step-up transformer ratio, such as 1:10 or 1:20, for your moving coil cartridge and your MM phono stage. It then checks two things: that the phono stage will deliver a normal line-level signal, and that the cartridge will see a load it is designed for.

How it works. A transformer with a 1:N ratio multiplies the cartridge’s voltage by N, and divides the phono stage’s input impedance by N squared: 47 kΩ seen through a 1:10 transformer becomes 470 Ω at the cartridge. The calculator applies these two standard rules to your figures. The signal is judged at the phono stage output, where 0.25 to 0.70 V is a normal line level. The load is judged against the cartridge’s recommended minimum and against ten times its internal impedance.

Limits. It cannot tell how a particular transformer model measures or sounds. Use the result as a starting point, then check the transformer’s datasheet and listen.

Example. A cartridge with 0.4 mV output and 6.8 Ω internal impedance, into a 40 dB MM phono stage: a 1:10 transformer gives 0.40 V at the phono stage output, and the cartridge sees 470 Ω, well above its 75 Ω minimum.

Made by. Le Son, Shanghai. Built in July 2026, updated in September 2026.

How to cite. Le Son, Step-Up Transformer Matching Calculator, leson.org/step-up-transformer-calculator/