A SoundTraxx Tsunami, Elektronik Solutions Ulm LokSound, or Digitrax SoundFX decoder would probably be the best choices for all of these engines. The last thing I would ever consider is an MRC sound system.
How old are the P2K engines? They may be "DCC Ready" and have a decoder socket inside the tender. If not, more wiring is going to be involved.
The only IHC model I know of that is DCC Ready is their currently-offered 2-10-2. That is not to say that sound cannot be installed into an IHC tender, but it will require more wiring if there is no DCC socket.
One quick way to determine if the P2K locomotives are DCC ready is to look between the engine and tender. If there are several wires interconnecting them, then there is a DCC socket in the tender.
One thing you should know if you go loksound is that you DO NOT need the programmer, the only thing that does for you is allow you to download sounds from thier library, but the decoder will program normally on any programming track, you dont even need a booster like you do for some decoders. I suggest you order from Tonys Train Exchange, and if you do they will load whatever sounds you want on the loksound decoder before they ship it to you.
In the steam sound market, Loksound and Tsunami are pretty equal. Loksound has a better drive, your motor will run quieter and more smoothly, but I have heard that the Tsunami has a little better sound. However, at this point Loksound is unquestionably the best decoder for diesel sound. The Tsunami is also cheaper, so that could factor in to your descision. Both are great decoders and you will be happy either way.
Always the hardest part about installing sound is installing the speaker(s) in a way which will give you the best sound. Steam engines are easier than diesels because you have a nice big tender to work in, a good and common way to mount the speaker in a steam engine is to have the speaker facing down through the tender floor with holes drilled in the floor to let the sound out. You should also use a baffle/enclosure and make it as air-tight as possible.
Good luck
WITH SOUNTRAXX TSUNAMI THERE IS NO PLUG SO YOU NEED TO CUT AND SOLDER WIRES
Not quite true -- with the SoundTraxx Tsunami, you can purchase a wiring harness with an NMRA plug on one end and the 9-pin JST plug on the other, and replace the solder-in wiring harness that comes with the Tsunami. A very easy conversion to make the Tsunami truly plug-n-play.
I recommend studying the Tsunami and other decoder sound features on their websites.
I have installed six Tsunamis, three in P2K locos, one of which is a 2-8-8-2. I just heard a Loksound in a PCM Y6B and did not like its chuff sound. I was even less impressed with the Digitrax at Phily. Only the Tsunami has 16 bit sound, which means the chuff, steam release and whistle all sound cleaner. While it doesn't have download, each of the three standard versions has between six and eight whistles to choose from.
If realistic steam sound is desired, the Tsunami has exclusive features, i.e., the chuff loudness, timbre and rod clank (only on Tsunami) can all be modulated by acceleration/deceleration. A realistic downhill "drift" effect is easy to create. The sound spectrum can be optimised by a seven-band equalizer, and the "liveness" controlled with reverb settings. Articulated chuff can either have a fixed cadence or can be set to slip at one of three rates.
Keep in mind that Loksounds require 100 ohm speakers, which limits choice of sizes.
The Tsunami is supported by extensive well-written tech manuals, more than can be said for the others. So the choice seemed obvious to me.
Hal
I haven't seen or heard a Digitrax FX decoder, but their advertisements in Model Railroader and Railroad Model Craftsman indicate that they have steam sounds available -- is this another case of something being advertised 6 months before it's actually available?
First of all, I have to ask for forgiveness for my ignorance - I haven't even thought about motive power for 6 months while I got track laid, and I'm certainly not up on the latest in sound decoders.
Are any of these decoders specific to articulated steam? Don't you need 2x the 'chuffs' with articulated (excepting the unlikely situation that both sets of engines were in perfect synch)...?
The only articulated I have with sound is a BLI T-1 4-4-4-4 and it has a distinctly different (busier?) sound than any of my other steamers.
I have a strong interest in the answer, as I too have a Heritage 2-8-8-2 for which I'd like sound one day.
I have experience only with the SoundTraxx Tsunami, and know that it can be programmed to represent either a standard 2-cylinder engine, 3-cylinder engine, simple articulated, or compound articulated.
cacole I have experience only with the SoundTraxx Tsunami, and know that it can be programmed to represent either a standard 2-cylinder engine, 3-cylinder engine, simple articulated, or compound articulated.