The new Heat Blaster HBL-4 became more powerful distortion pedal with rich harmonics for a more aggressive distortion going from classic rock to modern hard rock. Its edgy aggressive sound got closer to the high gain tube amp sound while retaining picking nuance vividly. An internal circuitry doubles the 9V supply voltage to 18V, achieving wider dynamic range and more amp-like sound. With its SCT circuit (Single Contact True-bypass), the audio passes through a single contact instead of 2, resulting in much higher sound quality and reliability, reducing any change or deterioration in sound quality. Its DCG circuit (Double-Contact Grounding) provides two points of contact to the pedal's ground circuit, making it more difficult for a loose connection to occur and also improves the sound quality.