I was able to create a new horn recording for 4 of my locomotives and thought that you might be interested in the process I took to make it work.
Mark's ADPCM tool is absolutely incredible. He got me up and running with the application, and I wanted to share what I've learned and what I've done with the tool to create a brand new horn sound.
In the video, I used a Proto 3 Amtrak Genesis, but I've had similar success with a 5 volt proto 2 Mikado, so anything Proto 2 and 3 should work.
The process was too much to type out, so I made this video
Of course, a big thank you to Mark for developing this!