DCC GP 9's

[Doneldon]

bap-

By all means, make some holes to let the sound out. You can drill holes as big as a quarter inch. Drill as many as you can. Equally
important is sealing off the back of the speaker(s). A speaker which is not enclosed emits sound waves from both the front and the
back. However, that doesn't mean more sound because the sound waves are perfectly out of phase and will cancel one another out. In
theory, that means complete silence; in practice it means much less sound volume but, more importantly, seriously distorted sound.

Your enclosure need not be fancy. Many model train speakers have prefab enclosures or such enclosures can be purrchased where you
obtained the speaker. Or, you can build an enclosure from styrene. Be sure to use a dab of caulk or flexible glue on the hole through
which the speaker wires exit the enclosure. Even such a tiny opening will interfere with getting the best sound out of your model.

                                                                                                                                         -- D

[richg]

Does any one know if the DCC only equipped GP 9s are machined so one could add sound. Are the frames and components like the ones with sound. Bill

Below is a link to the GP7 diagram which I suspect is similar to the GP9.

http://www.bachmanntrains.com/home-usa/dwg/dwgs/H624X-EXPLODEDVIEWII.pdf

Rich

[bapguy]

Bachmann was nice enough to provide a space for a 1" speaker. The units come with a 3/4 round plastic ring that goes on the back of the speaker. This faces up toward the motor and the cone faces down. I might try a bunch of small wholes first.  Joe.