Fitting DCC Sound to a Bachmann Class 37


This article describes the process of fitting DCC sound to a Bachmann class 37 locomotive:


Sound Decoder

My sound decoder of choice is the excellent ESU Loksound:


These decoders are a single package, combining traction control with 4 functions and sound. They are back-EMF decoders and provide excellent control. Because the decoders integrate traction and sound, the sound is properly synchronised with the motor operation.
The ESU decoders come supplied with a speaker and a baffle box into which the speaker fits. Wherever possible, I try to fit the larger ESU 40x20mm speaker as this gives better sound reproduction.


Loco Preparation

This version of the Bachmann class 37 pre-dates DCC sound and consequently, does not have space for a speaker with a standard baffle box. A standard speaker will fit, provided an improvised 'baffle box' is installed. To fit larger 20x40mm speakers would either require chassis block modifications or a reduction in height of the speaker baffle box.


Wiring

This locomotive is DCC Ready and contains an 8 pin socket:


Note how the speaker has been sealed using blue-tac. Sealing the speaker increases the volume and 'boominess' of the sound.


Bodywork Modifications

Sound is not very effective unless it is allowed to 'escape' the loco, otherwise it is 'caught' inside the model, reverberates and can create strange noises in the bodywork which are not heard on the prototype. To this end, I normally drill out exhaust outlets and replace fan grills with proper meshes. Generally it is a good idea to place speakers under these meshes or in the fuel tanks facing downwards.


CV Adjustments

As supplied, this sound package is very quiet, therefore, the sound volume was turned up.


Results - The Model in Action




Graham Plowman (21/10/2010)


Locomotive supplied by:
Woodpecker Model Railways

Locomotive manufactured by:
Bachmann

ESU Loksound decoder, sound and speakers supplied by:
Southwest Digital


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