I have considered adding sound to my DD40AX with a GP40 decoder. What I have been told is that some sound decoders have a setting called reverb (an echo) which makes it sound like there are two prime movers running.
Personally I would install two GP40 sound units, one for each prime mover in the DD40. The exact engine sound you need is a 645e3a with 16 cylinders.
Hello, anybody knows what decoder & sound will be fine for the new HO Bachmann DD40AX? Thanks.