Abstract: A system for adapting a tracker bar operated automatic musical instrument to play electronically stored performances includes, in one embodiment family, a channel plate member having parallel channels in the upper face. First and second spaced apart holes are provided in each channel. An array of solenoid operated valves individually open and close first holes in the channels in response to energizing signals selectively applied to the solenoid coils. The second holes are oriented to interface with the tracker bar holes so that opening a given solenoid operated valves exposes the corresponding tracker bar hole to atmospheric via the corresponding channel. Left and right adjustable bracket assemblies are adapted to respectively engage the left and right pay-off spool mounting members to juxtapose and maintain the channel plate member in the operating position.