Finally got around to a decoder and speaker upgrade in one of my Athearn Big Boys. I saw John's Challenger upgrade years ago and have been meaning to do this as I've never been fond of the OEM decoder both for sound and motor control.
There are two screws under the coal load and the rear-most water hatch. Remove two more from the bottom back-end next to the coupler and the shell will slide off. After removing the stock speaker, weight enclosure (I use that term loosely), circuit board and such, I then cut the middle post out of the tender. This leaves you with your red, white, black, orange and grey wires all tied into a stock plug. There are also wires soldiered to the tender trucks on both sides, so I tied all the red wires together and all the black feeders together. I also built styrene pads to elevate my speaker enclosure off of the uneven "floor" of the tender:
This leaves quite a bit of room so I used a CUI 13x18 cell phone type speaker in the largest custom enclosure I've done in N scale so far. I sealed up the enclosure with liquid electrical tape and coated the walls of the enclosure with a thin layer to dampen vibrations. I decided to try using cotton swab from a q-tip in the inside of the enclosure as well to further dampen things. Here is what it looks like with the LokSound Select Micro on top:
I included three SMD capacitors (not sure it is necessary with the amount of wheels touching track with this loco!) and mounted a nano LED in the rear headlamp (not shown). I snapped this photo before final button up where I cleaned up the wires a bit:
I programmed the LokSound with their latest Challenger file which sounds fantastic. The Full Throttle function is especially neat if you have some momentum programmed in (or even if you chop back the throttle very quickly) as the loco will coast a bit and the chuff sounds fall off to reflect that there is no load on the loco. Here is a clip of the sounds I took with my phone (apologies for quality and quirks!):
Overall I'm very happy. After running LokSound's CV54 motor calibration, it runs very, very smooth and crawls at speed step one. There is a noticeable difference between this and the Kato 4-8-4 844 that I did a LokSound decoder in recently. I used an 11x15 speaker in a smaller enclosure on that loco and the two are quite different. I need to get another video clip with a comparison next.
Anyway, thanks for reading!
-jamie
