i have never done this-so you may give my thoughts appropriate weight
assuming that you do not have the option to use the lighting socket-or chose not to
here are my initial thoughts-the card and really most importantly the speaker should be in a cabinet /box for best sound and most bass response--the box should be of rigid material and the speaker should have a seal or baffle so that the box is more or less airtight-not essential, just so you know-dont have the card but perhaps you could mount the card and speaker separately-speaker alone on roof, card below in cab......
based on the assumption you WILL NOT be utilizing the lighting plug (as i understand there isnt one on your engine)
the next thought for your convenience in fiddling-would be to carefully prise apart the plug-this i have done and with care the plug separates and the teeth which penetrate the wire can be preserved for future use-the plug as i recall has small clamps on the sides
next i would add a length of wire to extend that of the sound cards -this will allow you to move it about etc with less cramped quarters-it can be curled up or otherwise dealt with-you may wish to consider adding an 'on' switch in the extended cable-always nice to be able to turn off the sound
i always try to avoid chopping my LGB in any way and the following is based upon that approach
first -you should be able to connect the sound card via the wires to the reversing light on the cab-i suggest you do this -if at all- by a bus type connection -ie simply strip a bit of the wire off mid section and solder in-
if not -youll need to run wires to the motor block -which will likely require you to saw or cut small notches in either the floor or cab wall or both in order to have the wires clear things-likeise you may need to create a channel for the wires in the motor black case as well for proper re-fitting into the chassis-i did this when installing a smoke unit -using the awl on my siwss army knife -actually the best tool for the job despite a bench full of modeling and other precision tools i have
next
you could put the sound card against the roof of the loco, speaker facing down-attaching it with a good rubber cement which can later be picked off or otherwise removed-another option would be to utilize the existing mounting holes for the whistle as an anchor-(just a thought)-or simply use some self tapping screws -which will probably screw up the roof unless you were to add say a strip of glued on plastic as a mounting point for the screws
another option -if you decide to use a 'cabinet' would be to simply place the cabinet in the area behind the boiler-wont look very nice but would be extremly simple and might provide nicer sound-i dont know if you could attach to the back wall close to the light and remove anything on the back wall and create a enclosure that acts as a cabinet and might look like an internal coal bunker
best of luck
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