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Hornby R8117 TTS Sound Decoder for Princess Coronation (Duchess) class loco

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i have bought a brand new model of Queen Elizabeth that was the first of the revised versions of the Princess Coronation class locos and was reading the review of the same in a 2019 issue of Hornby magazine where it states that a TTS sound decoder for this loco was being produced, R8117.  However, a search on eBay and via Google cannot find any stocks of this decoder in the UK.


Does anyone know whether Hornby have just run out and are waiting for more or whether this is a discontinued item?  There is another option for fitting sound to the loco in the same magazine using a Zimo decoder from Digitrains but this costs around £100 compared to the £38 for the TTS decoder.  Alternatively, if anyone has the R8117 decoder they would like to sell or know somewhere that has one left in stock, I would be grateful to hear from them.





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Being a factory-coded item, Hornby make these in batches then produce another run in their own schedule.

They would rather have a slight backlog & keep the factories running at 100% than have an excess of stock & put all production facilities on hold for a while.

The Duchess is in the current range so I see no reason Hornby would have discontinued the decoder. I expect them to have another run planned ... but when?


The logistics of a Zimo decoder are different. These are produced without sound files so can be made in larger numbers. The sound is simply added by the dealer from a selection of files.


£100 will not include a speaker, so you need to add this (although you may want to replace the standard TTS speaker anyway because almost anything else would be an upgrade).


Other than availability, the benefits of the Zimo are:

It has better overload protection & higher current capability (although these should be irrelevant for a Duchess).

It will provide smoother performance.

You can adjust sound levels properly. My only TTS (a class 60) totally ignores any sound level adjustment & the spirax valves are louder than the engine sound).

It will cope with 4ohm speakers, allowing a better selection.

You can adjust the exhaust beat speed to put it in sync with the wheels.

It supports 4 'spot' sounds instead of the TTS' 1. Spot sounds include whistles, injector, fireman shovelling coal, steam, blower, safety valve. On a TTS, if you sound the whistle while the blower is on, then it fades out the blower, sounds the whistle then fades it back in again.

Both Digitrains & YouChoos have options for Active brake: In addition to a long deceleration time (which you can set for coasting), you can apply the brakes with a key. It makes bringing the train to a stop much more controllable.


The Zimo is a better decoder, but are the differences worth the extra to you or would you prefer to wait for a TTS to be put back into production?



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For the reasons detailed above, the TTS steam decoders tend to be the last to sell out so you might find one at a smaller shop thats not one that always comes up in peoples searches. TTS is fine for the money if you're willing to live with the compromises, but a lot of people aren't which is why so many people go for the more expensive options. The TTS diesels are better because the sound is reasonably in sync with what the loco is doing.


Reliability is also worth considering, the TTS decoders seem very prone to issues, if a Zimo or Loksound decoder lasts 3 times longer it probably represents better value over all.



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  • 4 months later...

I never noticed this thread before hence the delay in answering. I only noticed because I was searching for a Hornby Duchess TTS. I think you will find that the TTS decoder hardware is the same for all variants, Hornby effectively just do the same as Zimo and load relevant sound files into the hardware. It is just that Hornby make them in batches rather than program them one at a time. They may run different software levels as when I was having issues I checked the software ID on the different ones I have. Yes, I agree with Richard Croft the Zimo is a much better product, but it should be seeing as it is more that twice the price but for that you get much better hardware and memory which is one of the reasons they sound better. From my experience the TTS decoders have a lot of issues especially if it is a hot day, there does seem to be an issue with heat dissipation, but in my case I use them because they are not much dearer than a decent decoder. The short circuit protection is tons better on a Zimo, I must admit of the three makes I like Zimo the best. I did have one Hornby TTS decoder that switched off the sound with one of my locos, I spent about a week trying to figure what was wrong, even swapping TTS decoders. In the end it seemed that there was some interaction between the motor on that model and any TTS decoder. In the end I bit the bullet and replaced it with a Zimo, which never gave any issues. Funny thing is that decoder is in one of my other locos and works perfectly.

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If you require a Stanier 3 Cylinder Sound decoder on a ESU Version 4 decoder, including a speaker for £85.00 + some postage, then your in luck as we have some old stock left of these.


Just ring [email protected] on 01132 563415 to get this South West Digital Sound project.


Hope this might help.  Charlie



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