Fitting DCC sound to a Heljan Class 52

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This article describes the process of fitting DCC sound to a Heljan class 52 locomotive:

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Sound Decoder

My sound decoder of choice is the excellent ESU Loksound:

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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 and a bass-reflex speaker as this combination gives better sound reproduction.

Loco Preparation

The Heljan class 52 does not require any chassis block modifications because there is suitable space above the bogies to locate the standard ESU speaker. To fit larger 20x40mm speakers would require chassis block modifications.

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Note how the bass-reflex speaker has been located in the fuel tanks.

Wiring

This locomotive is pre-wired for DCC and has an 8-pin DCC Decoder Socket. The loco also has directional lighting. Installing the decoder is simply a matter of plugging it in and securing it in place with a double sided sticky pad.

'Westerns' had two Maybach diesel engines, located at each on of the loco.

It is permissible to wire two speakers in parallel, but ESU recommend keeping the volume below '53'. In practice, is was found that at default volume levels, the sound kept cutting out and this occurred because the impedance of the speakers did not match that of the decoder. To ensure that correct matching occured, the speakers were wired according to method #3 in our DCC Sound Speaker Wiring article.

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 by SWD, the decoders have the max volume CV (63) set to 50. The class 52 is an incredibly noisy locomotive! CV63 was reduced to a value of 20.
The Howes product was supplied with a volume setting considered to 'sound about right'.

Prototype Videos

D1015 leaving Newton Abbott
Western Ranger Cab Ride
D1013 Western Ranger's B engine powers up to full power - listen to the turbo charger scream!
D1015 Front Window Thrash
D1062 Western Courier
D1013 Western Ranger on the SVR
D1062 Western Causes a stampede at Burrs
D1062 Western Courier hellfire Departure from Irwell Vale
D1015 Western Champion Full Start Up
D1015 at Lickey
D1015 Western Champion Get away
Western D1015 big clag Dalish Warren
D1015 departs London Paddington
D1046 arrives and departs Yeovil Junction - clouds of smoke

Results - The Model in Action

Class 52 – "Clagging" 1 - Howes Sound

Class 52 – "Clagging" 2 - Howes Sound

ESU Loksound Decoder, sound and speakers for the above videos supplied by:

Bass Reflex Speaker supplied by:

Class 52 – stopping - South West Digital Sound

Class 52 – at speed - South West Digital Sound

ESU Loksound Decoder, sound and standard speakers for the above videos supplied by:

Graham Plowman

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