Those looking for an easy, very good solution for adding sound to your ATLAS S-2 and S-4 should consider the new MRC sound decoder. My overall opinion FWIW is I like it a lot.
Sound is a touch “tinnie” due to the penny size speaker with not much of a baffel. I had to quiet the sound down to the lowest settings and this made a big big improvement in sound quality. There are ancillary sounds such as the compressor and air release that come alive when you quiet down the engine exhaust. Some sounds are random and makes the little switcher very entertaining. The bells are selectable, the volume and period between rings is adjustable. Same with the horn. These are also selectable and of course the volume is adjustable. The lower settings have a much more believable sound. From start up sounds, idle sounds, and running sounds MRC has done a very good job.
Some say the sound recording is from a 244 and not a 539T for these engines and I think this is right. The exhaust rumble and that peculiar ALCO sound has more to do with the combustion control system that controls ignition, RPM’s, spooling up etc. I have the LokSound sound decoders for the S-1 and S-3 non turbo charged 539 and there is a difference but not that perceptable. For 68 bucks, including a speaker, from Tony’s this is an economical easy sound project in what is otherwise a tough sound project due to size.
The installation is easy. Remove the light board, solder the pick up wires to the “lands”. You need to file a few spots on the frame to make it fit and this is minor. I used electrical tape to insulate the frame from the new decoder as the power is directed to the lower brush via the frame and to the upper brush via a copper bridge that is bent on the bottom of the decoder board to touch the upper motor brush holder. Older versions of this switcher has 1 screw holding the light board, newer ones have 2. Mine was the older version. The LEDs are positioned to provide headlight a