This is a Rectify Series drop-in speaker system for Rapido FL9 locomotives. No modifications are required to replace the factory speaker. I used double-sided carpet tape to adhere the speaker to the chassis.
 
The speaker comes fully assembled and tested.
 
Dimensions are: 16mmH x 30mmW x 31mmL
 
The LokSound 5 versions of these locomotives have seen significant sound-quality improvements. The stock sound file on the Select/V4 versions for these locomotives are less desirable and the Hancock air-whistle has unneeded low-frequency modulation that causes low-profile drivers to distort. Even some of the early ESU Hancock recordings have this issue. In these instances the Hancock volume and/or master volume will need to be reduced to prevent speaker-crackle. LokSound Select/V4 FL9s that do not use the Hancock whistle will not pose any issues.
 
VIDEO: https://youtu.be/-iis1K3EkGo