Sounddecoder

[FPVonk]

Hello,
Here from the Netherlands a question;
I bought a Bachmann 'HO' EMD DD40AX Centennial (DCC) Union Pacific #6927, item no : 62102 and I want to build in a sounddecoder. Can some one tell me wich brand or make and type I should buy and if it is easy to install some pictures or drawings for building in the decoder would be nice thank you very much.

[ABC]

This locomotive has two prime movers, so if you want to try and simulate that you will need either two speakers attached to one decoder or two decoders with a speaker each.

[Jim Banner]

You have two options for adding sound to your locomotive - either add a sound only decoder or replace the present decoder with one that includes sound.  This is easier and usually more satisfactory than adding a second decoder.  Soundtraxx produces Tsunami sound decoders with the 645 engine sound.  Others may also.  I do not have a number for the stall current of your locomotive so be sure to measure it before selecting a decoder.  This link will take you to Soundtraxx's website:

http://www.soundtraxx.com/choose/choose3.php

The hardest part of your installation will probably be mounting the speaker and its enclosure.  If you want to add a second speaker, make sure that the two speakers combined give the correct impedance.  I believe the minimum for a Tsunami decoder is 8 ohms.  If you connect two 8 ohm speakers in parallel, you will damage the decoder.  Two 16 ohms speakers in parallel or two 4 ohm speakers in series will give the correct total of 8 ohms.  Two 8 ohm speakers in series will work too but may be slightly quieter.  Two speakers driven by the same decoder will improve the sound, particularly the low frequency parts of the sound.  But they will NOT give any better simulation of two engines (prime movers) than a single speaker will.  Using two sound decoders would be, in my opinion, a waste of money.  Normally, the engine sounds will ramp up and down together and you will hear very little difference between having one or two sound decoders.  (Articulated steam locomotives is a whole different story, even though they too have two separate engines.)  Better to keep your guilders in your pocket for the next project.

Jim

[Doneldon]

FPV -

Using two speakers with one decoder won't simulate two engines at all, since they will have identical sound, but they would likely improve the sound a bit.  Two decoders, each with a speaker, isn't really a practical solution.  It would be an expensive proposition and would offer little or no improvement in the sound experience over one decoder feeding two speakers.  I'd urge you to go with a single sound decoder (or combined sound and motion decoder which would be best) and the largest speaker you can install.  This will probably mean an oval speaker.  Be sure to seal an enclosure around the back of the speaker.  An ideal alternative would be one of the prefab base reflex speakers now on the market.  Good luck with your sound project.

                                                                                                          -- D