Fitting DCC Sound to a Class 42

This article describes the process of fitting DCC sound to both a Mainline (loco on the left) and a Bachmann (loco on the right) class 42 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

Neither of the locos being fitted are DCC Ready and must therefore be hardwired.
The Mainline model has been fitted with a 'Fiddleyard' chassis (no longer available) which has a Mashima motor driving cardan shafts to both bogies for all-wheel drive and all-wheel pickup. Its speed performance matches the bachmann model very well such that the locos can be double-headed easily.


Neither of the locos being fitted are DCC Ready and must therefore be hardwired.
The following pictures show the Mainline model with the speakers located with their baffle boxes in the roof. The left speaker is a bass-reflex which handles the low frequency bass sounds (of which there are many on this loco), while the right speaker is a standard 40x20mm speaker which handles higher frequencies.

The following pictures show the fitting of the decoder and speaker to the Bachmann model. The speaker is also fitted in the roof as there is no space to locate the speaker anywhere else. Unfortunately, there is insufficient roof for the baffle box, therefore, a sealed enclosure has been made around the speaker:

When testing, it was found that the motor in the Bachmann model exhibits a 'humming' noise - nothing wrong with it - it just isn't a very quiet motor! I suspect that the new versions of this model probably have a different motor which is silent.

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.

Results - The Model in Action

Class 42 - stopping

Videos of Prototype Warship Locomotives

D832 'Onslaught' Accellerates from Doniford (WSR)
D832 'Onslaught' arrived and departs from Blue Anchor (WSR)
D832 'Onslaught' leaves Doniford (WSR)
D832 'Onslaught' at Stogumber

Graham Plowman (28/09/2009)


Following the writing of this article, the cause of the motor 'humming' on the Bachmann class 42 was found. I was never able to properly 'tame' this loco to its decoder - it kept jerking, no matter what motor CV setting were used. It did the same on DC with the decoder removed. I subsequently removed the motor and found that it had a 'binding' spot at one point on its revolution. A new motor was duly purchased and installed and the 'humming' disappeared (9/6/2019).

ESU Loksound Decoder, sound and speakers supplied by:
Howes Models Logo

Bass Reflex Speaker supplied by:
DCC Supplies Logo

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