LEGACY PRODUCTS INCLUDING PROLOGUE ONE, TWO, FOUR, FIVE, SIX, SEVEN AND DIALOGUE ONE, TWO, FOUR, FIVE, SIX, SEVEN
Please refer to the list in your owner’s manual, with this addition: All PrimaLuna products from day one can use the newer KT120 tubes as well as KT150 tubes. The only exception is that smaller chassis products like ProLogue One, Two, Four, Five, Six, and Seven as well as ProLogue Classic and EVO100 models, are all NOT KT150 compatible. Some customers have used KT150s in those models and have not had an issue with them, but the factory does not support that idea.
Models that came stock with EL34’s (the ProLogue One, Four, and Six and DiaLogue One, Four, and Six models) can have the bias manually adjusted "hotter" on the Adaptive AutoBias board to work better with these “larger” tubes, resulting in more dynamics and pop. Click here for instructions. The newer series products like ProLogue Classic, ProLogue Premium, and DiaLogue Premium do this for you by having an EL34/KT88-KT120 switch.