Hornby Star sound installation (photos restored)

[Harlequin]

Here's my recipe for installing a big speaker in a Hornby GWR Star class loco to try to get a really strong sound from it.

 

I used an MX645 decoder because it has 3Watt audio output (at 4Ohms) and onboard stay alive circuitry. In the end I didn't use any stay alive because of space restrictions and with 12 pickup wheels the loco doesn't really need it. I wanted to install an enclosed speaker with a relatively big diaphragm and I settled on what some suppliers call a "MegaBass" and others call a "Box" speaker, which is 30 by 28 by 15mm. I removed the mounting lugs and cut off some material from the top to reduce it to it's smallest, simplest box form.

 

My technique in all steam sound installations is to give the sound a clear path out, not to be bounced around inside the plastic box before emerging through whatever holes there are in the chassis. To achieve this the speaker will face upwards and it will be hidden by a speaker grille made of coal...

 

My loco is the 2020 version of Lode Star which is accompanied by a 3500 gallon Churchward tender, not the biggest tender, so fitting the speaker and decoder required a lot of milling and chopping:

 

(Yes, a brand new loco and I'm immediately taking it apart and carving it up. You've got to have faith to do this!) The weight has been removed and its mounting posts have been milled down to base plate level. The circular speaker mounting has also been milled away, the inside faces of the fixing screw pockets have been removed so that the decoder will fit between them, and some of the base plate has been milled away so that the decoder can sit lower with the wires feeding directly into the central slot.

A lot of the tender's coal space had to be removed because, even with the base plate drastically flattened, the speaker just stands proud of the coal space floor. It will be hidden by the new coal load.

 

The 8pin circuit board has been removed and all the wires routed to the front of the tender through the central slot. The unwanted decoder wires have been shortened but not removed completely so that I can still strip back and solder to them in future if needed.

The speaker is positioned as far back as possible so that the coal load will have room to slope realistically towards the engine (we hope!).

 

After a few test fittings of the decoder, speaker, chassis and body I knew that it would all fit without any of the components being stressed so the next job was connecting up the wiring.

 

I had previously noted which of the tender's wires were the pickups and which the motor feeds so wiring up was straightforward: Red pickups soldered to red decoder wire, wrapped in heat shrink and tucked down to the right of the socket that connects tender to loco. Similarly blacks to the left of the socket. Orange decoder to red motor wire, Grey decoder to black motor wire. Purple decoder wires to the speaker. All insulated and then curled gently to fit in the the tender body.

 

 

At this stage I tried the tender on the layout, to check that it worked before I went any further. When I played the whistle the tender actually jumped sideways, so I knew I was on the right track to get strong sound!

 

The speaker adds some reasonable weight to the tender but I glued in some lead to fully replace the mass I had removed and to give the tender enough heft to stop it jumping when loud sounds are played:

 

 

Next, the coal load, which forms the speaker grille. A small piece of stainless steel insect mesh was cut and formed to shape:

 

 

Chunky real coal was glued to the mesh using Copydex:

 

The method is to dab Copydex onto the mesh and then pour coal over it, press down and leave to set before shaking off the loose pieces. It takes a few goes to cover the mesh and usually the last step is to fill individual holes with individual bits of coal.

 

When you hold the finished coal load up to the light you can see that there are many, many gaps for the sound to pass through. However, when it is installed in the tender those gaps are almost invisible. A speaker grille made of coal:

 

 

Finally, here is Lode Star back on the tracks with her new sound installation and detail parts added:

 

During the work I knocked off the tender handrails so they had to be refitted and carefully glued back in place but I managed to do that OK.

 

She sounds great, within the limitations of the sound project - very loud and the sounds are very clear. (I'm striving for clarity more than volume!) There is a bit of distortion on some very loud noises and I think that's the mesh or the coal vibrating against the tender body. Some tweaking and some more Copydex to stabilise the coal around the edges should solve that.

 

I will post some videos if I can capture something that does the loco and the sounds justice.

 

Edited May 26, 2023 by Harlequin

[Harlequin]

I have cobbled together a video of sorts...

 

 

I'm not sure it really does the sound justice but, anyway, there it is.

 

Edited February 1, 2021 by Harlequin

[Andy Keane]

Phil, just found this thread. There are some reasonable deals on Hornby Stars around and wondered what you thought of the running of yours under DCC. Does it have good slow speed control?

regards

Andy

ps - any chance of putting your photos back?

[Harlequin]

Hi @Andy Keane,

 

Photos restored!

 

As we've discussed elsewhere, my Lode Star has a definite "clunk" when the gear train reaches a certain state, about every 3.5 wheel rotations. I was unable to diagnose it so she still has it and I can still hear the "hammer-blow" on the rails when she's running at speed. She also cogs badly at low speed, despite the Zimo's excellent motor control....

 

Interestingly, Princess Alice, from the Troop train pack, does seem to be smoother but noisier at low speed. I wonder if she has a different motor?

 

Edited May 26, 2023 by Harlequin

[Andy Keane]

Phil

Thanks for this - the photos are most helpful and the coal grill a very neat trick - it should work on any tender loco I would think.

Andy