Hi Bill.
The standard Econami decoder has four different chuff sounds: light, medium, heavy and geared. By setting a CV, each of these can be turned into an articulated sound (essentially, double chuffs that are offset from each other a bit). For the EM-1, I think the "heavy" steam chuff with articulation would be the right choice (if the Bachmann version in fact is a "standard" Econami that has all the choices). The Econami also has 16 different whistle selections, along with different bells, dynamos, etc. You can "mix & match" all the choices via programming. See here:
https://www.soundtraxx.com/dsd/econami/econami_sound.php?s=steamIt's a good decoder. I've used a couple in the past, and my only gripe about them is that you can't get near-perfect matching of chuffs to wheel rotation at all speeds, like you can with ESU. But you can get the match pretty good, especially from, say, speed step 5 (out of 128) all the way up to where it doesn't matter anymore.
I think ESU's articulated sound files (e.g., it's Big Boy and Challenger files) have better-sounding steam chuffs, but the Econami is pretty good, and ESU doesn't have the range of bells and whistles to choose from that you get with the Econami.
BTW, I know it's picky, but technically, there isn't such a thing as a "simplex mallet." Mallet engines by definition used compound steam. The chuffs from a true Mallet sound different than in a single-expansion articulated, and I don't think the Econami's "fake articulation" really captures the sound of a true Mallet (like the N&W Y's) very well. But since the EM-1 was a single-expansion articulated, the Econami's design of using the same chuff sound slightly offset in time works well (I had one in one of my EM-1's once upon a time; since switched to ESU), although at high speed it begins to have a bit of a "gattling gun" sound . . .
John C.