So, those are my locos, QSI decoders with several speakers.
I normally put a speaker in the roof near the front of the loco so the bell and horn sound better, not coming out of the fuel tank under the loco.
Unfortunately no grill on the top, so my good buddy Dave Stubbs made small enclosures with 2 high frequency speakers firing out the sides (here you see 4 such units)
This fits inside the loco shell, firing out the side grilles. These also have mounts for the decoder, below you see an assembly mounted inside.
The rear cooling fan also gets a speaker:
There is also a speaker in the fuel tank:
All in all 4 speakers in each loco.
The recording does not do it justice as compared to hearing it in person. I will get a better microphone.
Greg