Name the rectifier for Det/Pre-amp of x and # tubes of 4
CREATE TABLE table_name_69 (
    rectifier VARCHAR,
    det_pre_amp VARCHAR,
    _number_tubes VARCHAR
)
SELECT rectifier FROM table_name_69 WHERE det_pre_amp = "x" AND _number_tubes = "4"
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: Name the rectifier for Det/Pre-amp of x and # tubes of 4 ### Input: CREATE TABLE table_name_69 (
    rectifier VARCHAR,
    det_pre_amp VARCHAR,
    _number_tubes VARCHAR
) ### Response: SELECT rectifier FROM table_name_69 WHERE det_pre_amp = "x" AND _number_tubes = "4"