Jacob - the "Nathan 3 Chime" file that Ring has is pretty much a K3LA...it sounds like a near match to the K3LA's on BNSF dash 9's in my area. The other Nathan recordings are indeed from MicroPrecision (who currently makes the Nathan line) but they seem to be all of modern make. They also sound like they were recorded in a recording studio, rather than outdoors as there is no reverb or echoing. I tend to prefer a good outdoor recording myself.
If you are looking for a specific horn (old cast vs new cast, etc) then you have a couple of options. Best would be to find someone that has one of those horns and record it yourself. That way the recording can be distributed to all Railpro users without copyright issues. The second option would be to find a good recording of the horn you are looking for online (train sim websites or Youtube) and turn that recording into something Railpro can use. This requires a converter to get the sounds from Youtube, and also an editing program like Audacity (free) to edit the recordings for Railpro. With this second option you will not be able to share the recording as it is not yours. If I understand copyright laws correctly (and I may be mistaken here) you can use someone else's recording for your own use, but not for distribution.
To create a horn file for Railpro you need to create three files: 1.) start, 2.) loop, 3.) end. Using Audacity you can cut the horn blast recording into those three. Start and end are easy enough. Getting the loop right is hard. You have to edit that part in a way that the file can be looped on itself without hearing any clicking, popping, or obvious signs of the file looping over itself. It's not easy to do. Ring does a great job with it on their horn recordings. I've done some, but it is hit or miss for me. Once you have the files, open up Railpro Assistant and create a new sound file, then load up the files you've created and your're done.
I made this horn recording for my own use off a Youtube video/recording:
-Kevin
