We have secured a supply of vacuum tubes, so we are resuming the limited-time special price of 9,000 yen. ● This is a booster that uses vacuum tubes. It adds the characteristic sound pressure of vacuum tubes and a slight boost to the original sound. This listing will include a used 12AT7 tube that we have in stock. 12AU7, 12AT7, 12AV7, and 12AX7 tubes can be used, so try different tubes you have to find your favorite sound. We recommend a 12V center-negative adapter for more stable operation, as a regulator is built-in. ● Although it's a booster, it's set to be almost a buffer at the 12 o'clock position to prevent distortion even when clean. ● Because vacuum tubes are used, there will be some hum noise compared to a transistor natural booster. This is not a defect. ● When placed after a tube screamer, you can enjoy the nuances of a vacuum tube even with a transistor amplifier. ● Recommended for those who feel the sound is thin with line inputs. Currently, several studio musicians are using it in their recordings. ● Hand-wired on a universal board. ● 9V battery cannot be used. ● Please use a 9V center-negative power supply, which is commonly used for effects pedals. (12V is more stable) ● Aluminum case size: 60 x 112 x 31 (height) mm ● True bypass specification ● EBK is a name used only for online sales. In our main business, we adjust, manufacture, and repair amplifiers, effects pedals, and other equipment, specializing in blues-related gear, and also adjust guitars. ● Six-month warranty: We manage customer records, so if a failure occurs during normal use, we will compare it with the shipping records and repair it free of charge within six months. (Shipping costs are the responsibility of the customer.) ● Shipping included. Please refrain from price negotiations.