Pure Vacuum Tube core Ringmod uses the pair of twin diode NOS vacuum tubes (included) as the ring modulator section. This replaces the commonly used solid state diodes and results in a modulation tonality few have ever heard. This Ringmod is fully controllable with level inputs for both Signal and Carrier as well as adjustments for Signal and Carrier feedback. Signal to Carrier mix as well as a wet/dry mix are also included. Multiple audio inputs and outputs make this one of the most controllable Ringmod units ever offered. An optional external power supply is necessary if you do not have 700mA overhead on your Eurorack power supply