First, I'd like to acknowledge that sound is a subjective matter similar to taste. For example, some people like to eat Anchovies, I do not. I worked part-time on a shortline railroad for 10 years. During that time we had multiple GP9s and F7s on the property. As a result, I became very familiar with first generation EMD sound from trackside, in the cab, and even from within the engine compartment. With this preface, here goes.
I use Digitrax DCC on my layout for train control. So my sound comments are about the P2K units running in DCC. I have several SoundTraxx sound equipped locomotives. In my opinion, the overall quality of the SoundTraxx EMD first generation decoder is superior to that in the new P2K GP9s. Granted, you have to install the SoundTraxx units yourself, and finding space for the speaker can be a challenge, but a modeler with average skills can do the job.
By sound element:
Bell -- It's a toss-up between the two.
Horn -- The P2K horn doesn't sound like anything I've ever heard. It's not quite a single trumpet "blat," yet it doesn't sound like a multi-trumpet horn either. SoundTraxx gives you the option to select various horn types and number of trumpets by setting CVs on the decoder. For example, you can select a single trumpet blat, 3-chime Nathan, or 5-chime Nathan. The sound they emit is a better representation of the prototype to my ear.
Prime mover -- The P2K unit sounds ok, but it's not quite true to my ear. What bothers me most is that it doesn't provide "transition" from series to parallel as the throttle increases. With SoundTraxx, there's a point between the 3rd and 4th throttle notch where you hear the prime mover throttle back, some relays kick in, then it automatically throttles back up with a change in the prime mover/generator sound now that the traction motors are running in parallel.
Dynamic brakes -- P2K's sound is slightly better because it provides not only the resistance grid "humm" but also the cooling fan sound.
Coupler "clank" -- Edge to P2K. In DCC is provides different sequence modes. For example, for uncoupling you first hear cut-lever sound, followed by the knuckle opening, followed by the air dump sound. SoundTraxx only provides the linkage and knuckle noise.
Air compressor -- Slight edge to SoundTraxx.
Track speed indication message. P2K wins this hands down (not provided by SoundTraxx). When you press function 10 on your throttle the P2K emits an audible message about your scale track speed. For example, it will say "one seven" for 17mph or "two two" for 22mph. Of course, the message changes throughout the speed range. A couple of members of my operating crew tend to run way too fast, so I can't wait to spring this feature on them. Bet they begin to slow things down after that!
Regards,
Tom Matty
