Analog bass line synthesizer with true analog circuitry for excellent bass sound and groove faithfully reproduces the original circuit using matched transistors pure analog signal circuit with sophisticated vco, vcf, and vca sawtooth wave and square wave vco with transistor waveform shaping circuit 4-pole low pass resonance filter with cutoff, resonance, envelope, attenuation, and accent controls be sure to check the detailed product description at the bottom and precautions before purchasing! to request a return or exchange, please note that it is mandatory to provide a video of the unpacking of the package.