I installed the SoundTraxx LC-090 with Alco sounds into my Atlas S-3 and I am very pleased with it. I’ve been around a few prototype Alcos, and even with the small speaker, there seems to be enough of a rumble to make it sound real.
In some correspondence with the guys at SoundTraxx, I learned that the source for their Alco sounds was an Alco S-1 at the Feather River group’s museum in California. This works out well for me, because the S-3 was nearly identical to the S-1. They both had the same 539 prime mover, and only the trucks were different. However, both the S-1 and S-3 were 600hp non-turbocharged engines. This means that although the engine sounds are similar to those of Alco’s 1000hp S-2 and S-4 models, what’s missing is the high-pitched chirping of the turbocharger as the locomotive accelerates.
Again, missing the turbo chirp is good for my S-3, but potentially bad for models of other Alco prototypes. Nearly all Alco locomotives other than the HH-600/660 and the S-1/3 had turbochargers, and remember that the RS-2’s and later models had the 244 or 251 engines in them - each with their own unique sound. In other words, as great as the sounds from the LC-090 Alco decoder are, they won’t make your S-2, RS-3, RS-11, or C-425 sound very much like their prototypes. I guess this is where the Lok-Sound decoders, with the ability to program more specific sounds into the same chip, might start to catch on.
Tom
PS: I guess another avenue for modelers of 251-powered Alcos is the QSI chip installed in the new P2K RS-27 models. I just don’t know if this sound unit can be obtained separately and installed in other Alco models.