A Sountrax Tsunami or micro Tsunami would be the way to go, the heavy steam version has the correct sounds, you even have whistle and air horn like the prototype. I'm more interested in how a sound decoder and speaker will fit in the tender with Kato designing it for one of their own slot-in decoders. A photo of the tender without the shell would be good to see.
There is plenty of room in a kato GS-4 tender, the weight is directed more toward the bottom of the tender. As for hooking the decoder up you can just use one of Kato's DCC decoders made just for the GS-4 to run motor control and the lights and use a micro tsunami for the sound. Im not sure how good the motor control is with their decoder is, Im sure its not as good as a lenz decoder but it is easier to hook up, you just replace the pc board in the tender with the DCC decoder from kato and presto thats it. then all ya have to do is solder the two wires on the micro tsunami onto the correct pickups.
I converted mine using the Kato DCC for motor control and adding Tsunami sound. The following link is a complete conversion. http://www.trainboard.com/grapevine...ami-install-Step-by-step!&p=479435#post479435 Harold
I have installed several of the Tsunami's into this locomotive. First off I will warn you that ALL units are NOT DCC friendly! I now isolate the motors in all of the units I do. I run two wires between the tender (decoder) and the loco for the motor. Before doing this I had several decoder failures do to the drivers hitting the motor frames. I also have not found it necessary to remove any weight. I mount the decoder on the top of the weight. The weight will act as a heat sink. I do as UP Phil did for the speaker install, but I just machine a small semi-circle of material at the speaker end to make room for the speaker enclosure. This leaves over 90% of the weight in its original place. The decoder and speaker and it capacitor will add some weight as well. The sound is very good and loud. I have had to turn the master volume down as it was too loud.
I am new to the DCC world and I am trying to convert my grandson's collection to DCC. I think the GS4 will be my first attempt. He has the newer version that says "Southern Pacific Lines" and already has the drive decoder installed. I would like to add the sound decoder to it. So from what I am reading here it looks like the the SoundTraxx #826003 Heavy Steam TSU-750 Micro-Tsunami is the best choice. But I do not see a speaker included with this decoder. How hard is it to add the speaker? And what speaker is recommended for the N-Scale Loco?
Not familiar with the loco or the decoder but if it is sound it will have two wires to attach to the speaker so that part is easy. I'd do some searches if no one can help here, someone probably can, but if you have room for a speaker without a lot of work I'd get the largest one that fits to a point. The point is that you want to put an enclosure on the speaker.... https://1fatgmc.com/RailRoad/Decoder-1/page-33.html .... it makes a world of difference in the sound vs. a speaker without an enclosure. You can see the speaker and enclosure on the left side of the frame above. Streamlined Backshop who I believe still advertises on here and others have speakers and enclosures. Sumner
Speakers without baffles/boxes sound fine when you directly in front of or behind the speaker (i.e. face-on in front or behind of the speaker). But in MRR locomotive installations, you are almost always around the edge of the speaker. The problem is at those locations, you hear equal amounts from the front and rear of the speaker, which are 180 degrees out of phase and cancel out. Hence they are much quieter. Mounting the speaker in a baffle/box eliminates that issue, and you get more net sound to your ear at typical MRR listening positions.
I know this is an old thread. Hopefully you found what you were looking for, but ESU has this: https://www.esu.eu/en/products/loksound/loksound-5-micro-dcc-kato/ I haven't installed it yet but it looks Easy Peasy. Plus, there's a ton of real estate in that tender, you can use an HO scale-sized speaker and baffle.
