This is a Rectify Series drop-in speaker system for Atlas Classic & early-run Master U23/30B locomotives. The speaker is a beautiful press-fit between the rear weight and motor mount. No frame/weight/shell modifications are needed! The factory PCB will need to be removed with either a Decoder Buddy installation or a hardwired decoder. Board-style decoders will not work (Soundtraxx PNP, LokSound Direct), as they take up all of the space between the two weights and leave no room for the speaker. If using a Decoder Buddy, you will need to install it as flat to the motor as possible and trim the excess pin-height after pressing the 21-pin decoder flat to the Buddy.
 
The speaker comes fully assembled and tested.