Pete Cornish TB-83 Extra Duplex Treble BoostMaker: Pete Cornish Model: TB 83 Extra Duplex Condition: New Description: The TB 83 Extra Duplex combines two of our TB 83 Extras in one pedal to give you flexibility and different tonal colors to play with. Set each one to different volumes to give two different degrees of boost and then combine them to obtain up to double the gain of each individual effect. This is the second Pete Cornish Treble Boost designed and built by him from the early 1970s