Adding a sound system to the Hornby Class 60 freight Diesel Locomotive.

Part 1: Fitting an ESU LokSound V4 decoder to an early version of the Hornby Class 60:  



I had started researching sound decoder solutions for the forthcoming Hornby red DBS Class 60 release (due Q3 2013). I ended up with 2 main runners, and I've decided to equip my existing (non-sound so-far) Class 60 with a promising ESU LokSound V4 solution straight away, while I await an equally promising future Zimo solution, which I will eventually fit to the forthcoming Hornby release in Part 2 of this exercise.


DB Schenker liveried Class 60. The intended recipient of the sound system.


The Starting Point:

My existing Class 60 is equipped with fully DCC controlled lighting, including day/night operation, rear light disabling and some double strobe add-on warning lights for yard shunting.

The decoder is at present an ESU LokPilot V4 21 pin unit, fitted via the ESU adapter board which includes amplifiers for the Aux3 & 4 outputs. A completely new main PCB circuit interfaces to the original Hornby lighting, dealing with annoyances such as the negative ground lighting PCB assemblies.



The Objectives:

The intention is to fit a Legomanbiffo sound project on an ESU LokSound V4 21 pin decoder, which can be plugged into the existing ESU adapter board, in place of the LokPilot decoder.  The speaker will be at least an ESU 50334 40x20mm unit, fixed within the full size original ESU enclosure or within a larger custom housing. 

When the new Hornby DBS liveried class 60 is released in Q3 2013 (I hope), I plan to equip this with an equivalent Zimo sound decoder. A comparison can then be made between the two decoder solutions.



The Challenge:

The choice of speaker location is somewhat limited.  My preferred option of using the fuel tank to form an enclosure is not possible without milling away the large piece of metal chassis casting that fills the centre of the tank. (The loss of adhesion weight by such action, would be undesirable, even if I had access to such a machine.)


The roof vent is yet another dead end, as this is moulded from solid plastic, with no airways.

In fact there only seem to be two main options:



1) There is room for quite a large bass reflex speaker above the drive shaft and below the exhaust silencer assembly.  However, substantial sound vents would need to be carved between the inner roof and the exhaust silencer assembly, to enable sound waves to exit upwards. There is an alternative air path through the floor, via the forward part of the bogie, but this has a fairly small cross section. This is sad as a bass reflex speaker would definitely fit, although I'm not optimistic about the volume or quality of the sound that would be produced through the available orifices.

2) At the other end of the locomotive are substantial side vents fitted with an open mesh. Behind these vents are dummy power unit parts, which can quite easily be seen through the vents. However, there is almost room to fit an ESU 50334 speaker & enclosure, in the roof, facing downwards above these side vents. In fact, some modifications would be needed to the dummy roof fan assemblies visible towards the top of the vents, to fit the speaker, and to provide a good cross section to the air path leading to the vents.  This looks the most promising approach so far.


These side vents may provide a speaker solution (note also the solid moulded vent in the roof above).


Enablers to get the speaker in place:

The decoder and accessory PCB assembly would have to be moved to the opposite side of the main PCB. Fortunately, there is plenty of room to accommodate them below the exhaust system. (Or so I thought :-)

The grey plastic mouldings imitating the roof fan assembly within the upper part of the side vents will need modifying to provide clearance for the speaker and to open up an adequate air channel to the side vents. The moulding is just a press fit to the chassis block, and can easily be removed. It is proposed to completely remove this part for initial testing. If all goes well, the necessary cosmetic mods will be undertaken and it will be refitted.  If however the sound quality proves unacceptable due e.g. to resonance effects within the body, then the original structure can be restored before alternative strategies are considered.


Moving the decoder assembly to the other side of the main PCB:

The double sided foam pad holding the Decoder assembly to the original fan housing was carefully cut through.  A 0.5mm plasticard plate was glued to the top of the chassis block in the new location, to provide a decoder mounting platform. Accessory PCB wires, that were too short for the new location, were replaced and the decoder assembly was reconnected in its new location. The dummy fan moulding in the original decoder location, was removed.

Showing the original non-sound ESU LokPilot decoder in place before I received the new LokSound

Unfortunately, the roof below the exhaust assembly was not quite high enough to accommodate the 21 pin socket on the decoder. So a hole had to be cut in the roof, below the exhaust moulding, to enable the locomotive to fit back together again.

Before the exhaust assembly was refitted to cover the hole
NB: The hole was greatly increased in size to accommodate the high spots of the larger ESU LokSound decoder (see photo near the end of the page).


Speaker enclosure:

Pending arrival of the speaker, a spare enclosure was glued to the roof underside, immediately above the side vents. 


The missing dummy fan assembly, removed from the chassis block is not too obvious.

The speaker enclosure is just visible if you know where to look, but is not too conspicuous, viewed through the mesh.


Quick check to confirm all is well before sourcing the speaker & decoder



LokSound V4 Decoder Programming:

1) Circuit diagram showing the Function Outputs in use:

The unchanged circuit for lighting control (V4 LokPilot and V4 LokSound have almost identical function control systems, albeit very different defaults).


2) Adjustments to the Legomanbiffo function mapping:

A few additions to accommodate lights and operational functions:

Function Button Bif functions as Received Sound Slot Preferred Sound Slot Action Summary
0 F Lights on/off - Day running lights - Add Day running lights FWD
0 R Lights on/off - Day running lights - Add Day running lights BWD
1 Sound on/off 1 & 2 Engine start/stop 1 & 2 None
2 High note horn 23 High note horn 23 None
3 Low note horn 24 Low note horn 24 None
4 Buffer clash 4 Buffer clash 4 None
5 Air Release 5 Air Release 5 None
6 Driver door slam 6 Driver door slam 6 None
7 Compressor 7 Compressor 7 None
8 Spirax valves 8 Spirax valves 8 None
9 Flange squeal 9 Flange squeal 9 None
10 Dispatch whistle 10 Dispatch whistle 10 None
11 F   - Night running lights FWD - Add Night running lights FWD
11 R   - Night running lights BWD - Add new programming line for 11 BWD Night Lights
12   - Rear lights off - Add Rear lights off
13 Sanders 13 Sanders 13 None
14   - Strobe lights on - add strobes
15   - Shunt mode - Add Shunt mode
16   - Zero Momentum mode - Add Zero Momentum mode
17   - Inverse fader - Add Inverse fader


Detailed CV change action:

Including, curiously, restoration of the headlight and rear light intensity, activated by button zero, which were almost at minimum settings as received!

Function Button Programming Line CV32 CV Changes
0 F 5 2 330=1;  0/262=31
0 R 6 2 346=2;  0/270=31
11 F 17 3 257=4; 266=4
11 R 32 3 497=8; 500=4; 504=0; 506=8
12 18 3 276=32; 282=16
14 20 3 or 0 3/314=32;  0/299=6;  0/303=128;  112=15
15 21 3 332=2
16 22 3 348=1
17 23 3 357=128; 365=8;  133=80

The (inverse) fader is introduced to provide a means of increasing engine sound volume when the engine revs increase at notch settings above idle.


A few tweaks to the sound levels:  

The engine sounds were reduced, to increase the relative volume of the horns and the wheel flange squeal sounds, which were already at the maximum volume setting.

Several remaining sounds need re-balancing with the revised engine sound volume:

Sound Sound Slot # CV# Original New
Master Volume - 63 128 90
Faded Volume - 133 128 80
Engine 1 1/259 128 70
Buffer clash 4 1/283 110 60
Air release 5 1/291 50 40
Driver's door slam 6 1/299 70 30
Compressor 7 1/307 110 60
Flange squeal 9 1/323 128 110
Whistle 10 1/331 60 128


It all works very well! The ESU 50334 speaker delivers a very acceptable sound through the side grills and after the above adjustments, the relative sound volumes are how I like to hear them. The original lighting all works as required, including the strobes and rear light disable facility.


Computer Control:

Next step is to add the updated Class 60 to the Traincontroller locomotive list, including all the new sound functions. Then a test track schedule will be created, followed eventually by a YouTube video.

The Class 60 runs smoothly at all speeds, and the motor control related CV values are as follows:


CV Purpose CV Number Original CV Value New CV Value
Start voltage 2 1 2*
Acceleration 3 190 -
Deceleration 4 100 -
Max speed 5 220 -
Half speed 6 110 80**
Config 1 (Various) 29 14 -
Config 2 (Various) 49 19 -
I-slow 51 0 -
K-slow 52 36 -
Control ref volts 53 76 -
K 54 52 -
I (momentum) 55 36 90***

*Start voltage is increased to overcome some hesitation at speed step 1/28

**Half speed is reduced to 80 to reduce the speed gradient at slow speeds.

***The Class 90 has a good sized motor with 2 flywheels which would suggest a value nearer to 100.

Showing the speaker installation and the fan assembly removed to enable it to fit.


The larger cut-out below the exhaust silencer, required to accommodate the larger LokSound decoder.


LokSound in place on the ESU adaptor board.



The sound system and the locomotive speed control plus dynamic acceleration / deceleration properties are very good. It's a pleasure to drive and works very well under computer control too. I'm not sufficiently familiar with Class 60 locomotives to be able to offer an opinion on sound accuracy, but Legomanbiffo's solution appears very convincing. I think the volume boost I've applied as the locomotive revs build up to the next notch above idle adds a bit of presence though. If I come across a 60 at Ely Station soon, I'll be listening carefully!


When Hornby release their imminent red DB Schenker liveried Class 60, I'll make an equivalent conversion, but this time using a Zimo decoder equipped with a new sound project. The Bif solution sets the bar quite high, so it will be an interesting comparison..... check out the Part 2 page when it appears.


Subsequent tweaks (April 2014):

With a year or so of additional experience on LokSound V4 projects, I've decided to make a few adjustments and add manual notching:

The acceleration and deceleration delays (CV3 & 4) could usefully be extended:  230 & 110

CV2 drop to 1, CV51 to 2, CV55 increase to 100, CV124 to 5 to allow adaptive speed control frequency.

Just discovered detonators on button 18  ! next I'll need a flash LED!

Manual notch-up on button 19: CV32 to 3 then CVN=CV397 to 2

Manual notch-down on button 20: CV32 to 3 then CVN=CV413 to 4

Revised Function Mapping
Function Button Preferred
0 Day running lights
1 Engine start/stop
2 High note horn
3 Low note horn
4 Buffer clash
5 Air Release
6 Driver door slam
7 Compressor
8 Spirax valves
9 Flange squeal
10 Dispatch whistle
11 Night running lights
12 Rear lights off
13 Sanders
14 Strobe lights on
15 Shunt mode
16 Zero Momentum mode
17 Inverse fader
18 Detonators
19 Diesel Notch-up
20 Diesel Notch-down



You've read the web page, now watch the movie:

Click here for the youtube video of the completed Class 60 in action


Adding a detonator flash LED .....  mini-project:  


A simpler circuit solution with a detonator flash LED added:


Revised Function Mapping
Function Button Preferred
0 Day running lights
1 Engine start/stop
2 High note horn
3 Low note horn
4 Buffer clash
5 Air Release
6 Driver door slam
7 Compressor
8 Spirax valves
9 Flange squeal
10 Dispatch whistle
11 Night running lights
12 Rear lights off
13 Sanders
14 Strobe lights on
15 Shunt mode
16 Zero Momentum mode
17 Inverse fader
18 Detonators
19 Diesel Notch-up
20 Diesel Notch-down
21 Detonator Flash LED


Revised Circuit Diagram to free up a function output to drive a bright white LED to flash in synchronisation with the detonator bangs:


Circuit Mods complete, Flash LED added and CVs adjusted:  All works fine!

Mounted a bit on the high side, but it does the job!


Supplier website links:  


Olivias Trains The resprayed DB Schenker Class 60 unit above was purchased from Olivia's. But broken front parts & missing accessories on arrival and no response to my email, rather took the shine away despite fixing the problems myself!    
Digitrains A good source of all things DCC including pre-wired chip LEDs from DCCC.
DC Kits D & E Video   Source for Legomanbiffo sound projects on LokSound V4 (and an ESU speaker).
Rapid Electronics A good low cost, high speed supplier of electronics components etc
Maplin A convenient local source for electronic components such as resistors and transistors


The photos of the Class 60 model were taken hand held on the kitchen worktop using a Canon IXUS 220HS.    


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