Table: all_american_five
Columns: tubes
converter
det_pre_amp
audio_amp
rectifier

Question: Name the rectifier for Det/Pre-amp of x and # tubes of 4
SQL: SELECT "rectifier" FROM all_american_five WHERE "det_pre_amp" = 'x' AND "tubes" = '4'

Question: Name the # tubes with Det/Pre-amp of x and audio amp of x x (push-pull)
SQL: SELECT "tubes" FROM all_american_five WHERE "det_pre_amp" = 'x' AND "audio_amp" = 'x x (push-pull)'

Question: Name the det/pre-amp with # of tubes of 8
SQL: SELECT "det_pre_amp" FROM all_american_five WHERE "tubes" = '8'

Question: Name the det/pre-amp with # tubes of 4 and rectifier of x
SQL: SELECT "det_pre_amp" FROM all_american_five WHERE "tubes" = '4' AND "rectifier" = 'x'

Question: Name the # tubes with audio amp of x
SQL: SELECT "tubes" FROM all_american_five WHERE "audio_amp" = 'x'