Bachmann GP9 installing Tsunami Sound


Putting Sound in a Bachmann GP9

I've been running a pair of GP9 Bachmann locomotives for about a year on my Colorado & Santa Fe railroad.  The only downside with the units was their permanent stealth mode.  This installation took me about 5 hours of work, much of it trying to figure out how I was going to mount stuff. 

The project is putting a SoundTraxx  PN 827101 Tsunami  Sound Decoder in a Bachmann GP9 with DCC on board.  The Speaker is a QSI 1.0 inch (26MM) speaker.

Remove the Shell
Here is the top of the GP9 with the Shell removed.  To remove the Shell, remove the one screw from the belly cover and you will see two screws holding the shell.  Remove those screws.  Remove the couplers and the shell should lift off.

Here is a picture of the bottom of the GP9 with couplers, belly cover and shell removed.  You can see the speaker enclosure under the belly cover. 

I removed all the electronics off the top, keeping the LED mounts and LEDs (not Pictured here).
Using Super Glue Gel, the Tsunami was glued to the covering about 2/3s of the motor access hole. Using a soldering iron I connected all the wires according to the Tsunami wiring diagram.

 The case will JUST fit properly if the LEDs are properly seated and their is no wires on top of the speaker/capacitor jack.  The capacitor will clear the shell lying on its side.  Route the speaker wires along side the motor wires to the belly.  Make sure their are NO Wires loose on the sides as they will jam and pinch against the shell when you put it back together. Be sure to wire in 680 or 1k ohm resistors with the LEDs or they will flash bulb on you.  I used Kapton tape to hold the wires in place after everything was tested and checked out.


Notice no wires on the sides.

Notice the Electrolytic capacitor  lying on its side

No wires on the other side either.

Speaker lying in place. I did not glue the speaker in place.
Using a piece of duct tape, I made an admittedly lousy baffle for the speaker.

Drill out the dimples on the bottom for a speaker baffle.  I used a #19 drill bit and drilled from the inside out to keep the flummers on the outside.


Thanks to Joe (bapguy) on the Bachmann Forum for this tip.  To set up the sound system, use the Athearn GP9 CV values, especially for the equalizer and the reverb units.  Made a world of difference on my finished model.

What I should have done - Replaced the yellow LEDs with bright white ones. Used a thinner Micro Tsunami instead of the full sized package.

Pictures and content copyright 2013