Model Railroading > Installing sound in a dummy unit

I’ve recently come across three undecprated dummy F7B units that I hope to make into bedraggled looking Penn Central power. 

Im new to DCC and sound, and I’d like to put sound in these carbodies. Are there larger speakers available for applications like this, and if so, are hey worth the effort?  The effect I’d like to produce is a whole bunch of 567s loading up individually, slightly offset from each other. And I’d like at least a few of the units to be louder than the others. Seems to me 5hatnwould be easier with a bigger speaker. 

Any my tips or suggestions?  I assume power pickup will be an issue. Will reverb inside the empty car bodies be an issue?

Way back in the beginning of DCC sound, a decoder occupied a complete box car. I installed the decoder in the end of the car closest
to the power source (the powered engine). I installed a micro-socket on the back of the engine under the walkway. The plug half of the
arrangement (which plugs into the socket on the back of the engine) connects to the decoder. Cut a horitontal slots in the end of non-
powered unit. Have a loop of wire inside with the decoder so there's no strain going around curves.  Since the non-powered engine you're
going to use has a lot of openings around the chassis, you'll need to create a baffle out of the upper half of the body, back of speaker
would be in this section, speaker would point down to the ground.  Drill some holes to let the sound out.
There could be variations to this method.  If you have ability to pick up power from the wheels in your non-powered unit, then you can
do away with the plug and socket between units.  Use decoders and speakers with 2 watts of power. remember half of the volume of
your unpowered unit is the baffle so that's going to enhance the output of the speaker.  Perhaps somebody  who has accomplished
what you're looking to do could chime in with their method. Let's not end this post with only one answer.
Frank30

It should be possible to fit multiple decoders and speakers in an empty F7B. You could use LokSound decoders with different 567 sound files. I think that would be the best way to replicate the sound of multiple locomotives from one unit. 

I will echo DH1205's suggestion for using ESU LokSound decoders.  Their website has multiple recordings of 567s from different engines.  Why is this important?  Because each will sound a bit different.  The thing you want to avoid is the exact same recording in 5 decoders in the same consist all launching at the same time.  They will "phase" and start to sound the same, because the ARE the same.  If each recording is slightly different, then it is much more realistic.

Of course, this requires learning their LokProgrammer software (free download), and purchasing their LokProgrammer computer interface ($145).  There are lots of videos on Youtube that explain various features of LokProgrammer.  If you have the time, it is worth pursuing.  If not, then there are multiple online DCC shops that could load it for you.  If this is going to be a one-off project, then it would be worth purchasing the decoders from a vendor that will be able to load the specific sounds desired as well. 

I have a similar project, where I want to have multiple SD40T-2 engines in the same lash-up, but they all have the same factory recording.  Fortunately the decoders are LokSound, and the sound files can be altered to get them to "harmonize" as an EMD turbo-charged chorus. 

The advantage you have is the empty shell of a B-unit will be able to fit a massive speaker(s).  Get ones with lots of bass.  it will turn heads.  :-D
The folks at RailMaster Hobbies have a good selection of high-bass speakers.  Rail Master