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Bachmann NRM Prototype Deltic
Sound Decoder Installation
by Doug Teggin

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Click here for the historical information and review of the model with installation of a standard DCC decoder.

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We were all impressed with the Bachmann model of the Prototype Deltic locomotive commissioned by the NRM.

As some people prefer to sell on their models for profit, others who keep theirs in a cupboard to gain some value, other who may have their model on display on the nice NRM Perspex base you will have some modellers who are running theirs on their layouts. Better still, you will have some people install DCC decoder into the model to get the best running characteristics out of it. Here I go a step further and install a sound decoder into the model.

I'm no expert in sound decoders, their selection, programming and installation so enrolled the help of Richard Johnson from DCC Concepts in Australia. Richard is a renowned DCC expert who runs a business selling and installing DCC equipment to customers around the World.

As my luck would have it, Richard had been working on some Deltic sounds. He collects sounds from various sources and mixes them for different models, finally uploading the sounds into the ROM chips on the DCC sound decoder.

Here is a video clip of a few Deltics, filmed in 1999. The sound is particular as you will notice:

Richard explained that the Deltic sound was very particular as the prototype had a twin 18-cylinder engines and the sound it made was phenomenal. A very difficult task to replicate in a model locomotive. Anyway we worked on this and put a decoder together. What we have here is work in progress. It will be improved and further developed. In the mean time we have a decoder that is now commercially available so owners of this model can enjoy it in their Deltic models.

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The decoder used is a ESU LokSound 3.5 decoder. This decoder offers all the great DCC features that are expected from ESU. It can be bought pre-loaded with specific or generic loco sounds or you can load the sounds yourself using the ESU LokProgrammer. This is how we have managed to get the Deltic sounds onto the decoder. You can purchase the LokSound decoder directly from Richard with the Deltic sounds pre-installed. You just have to fit the decoder.

Installing the Sound Decoder

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This particular LokSound 3.5 decoder came with an 8-pin NEM plug so I had to use a 8-pin to 21-pin adaptor. in future, both 8-pin and 21-pin LokSound 3.5 decoders will be available.

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You can't go wrong with the 21-pin adaptor, it only fits one way round. Socket #1 of the 8-pin part is clearly marked and you match up the orange wire of the decoder to this corner.

We see below the standard speaker and speaker housing that is supplied with the LokSound 3.5 decoder. It could be used if you wish. Just secure it in place with some blue-tack or UHU U-tac (yellow).

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The standard speaker is housed in a plastic round box. To get the best deep-sound results from this, the vents around the side should be blocked up with blue-tack. For this setup, I have used two of these 23mm speakers wired in parallel and I'm building a custom speaker box so I remove the plastic boxes by carefully prising the speaker from the box with a small screwdriver.

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It is best to measure the space available so you don't end up with a box that is too big for the space available.

There is a 10mm height restriction inside the cavity as there are the fans to consider. You can't build the box too high. Here are a couple of photos of the dimensions so you can see the space limitations.

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I am building a speaker box from balsa and plywood. The ply is 3-ply 1mm thick and the balsa is also about 1mm in thickness. To strengthen the wood, you can brush it with thin superglue (Cyano) that will soak into the wood, and improve the resonance of the box.

I've marked out where the two speakers will go. I drill out the speaker openings with a small drill and then I fix the two speakers to the top piece. They are secured with a universal cement that is applied to the back of the speaker and the surrounding wood once the speakers are in position. Don't use superglue as it will seep into the speaker under the metal rim and probably mess up the sound.

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You see below that I have made a base, installed the sides that are glued to the base. I've filled the seams with UHU-tac to prevent any air getting into the box. The top goes on. Cyano on the wood to wood joins and universal cement to the metal to wood joins. End pieces of the box are then glued on.

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I've build it like this as the space was tricky. some pieces had to be measured once others were in place. I can pop this box out if I now wish. The UHU-tac comes off easily.

You have to make sure that the screw pillars are free to go around the box. I lightly made some space for them on my one.

So you see in the photo below, the box is complete. It is airtight behind the speakers and the resonance of the box is reduced by using UHU-tac to secure it to the body. I did notice when testing the decoder with the round plastic speaker that the vibrations of the box were very audible. Reduce those and the sound quality improved dramatically.

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So what does it sound like and what special sounds lurk within this little decoder?

Well I was impressed. The quality of this sound is better than any sound I have heard to date on any Bachmann loco that I have listened to or any other locos that I've seen at shows and Toy Fairs. This one with the custom sound box is fantastic.

The video doesn't do the decoder full justice. As it is compressed for YouTube, the full range of frequencies are lost.

See and listen for yourself:

Dailymotion Video Player - Bachmann NRM Deltic Limited Edition - with Sound

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DCC Concepts configuration of the ESU LokSound 3.5 decoder

Information from Richard Johnson of DCC Concepts

Engine Sound:
The current engine sound set works really nicely and captures some of the complex resonances of the Deltic sound but still (to us anyway, we are rather fussy) lacks a wee bit of the energy that is very hard to achieve with the size of amplifier and speaker used in small Scale sound decoders. We are currently working on a possible enhanced set however this will be some weeks rather than days: (it will be a free re-load if we release it see our note below please).

We have not settled on a horn we really think sounds right so I have included two differing sounds for this a hi/low and single tone type.

Station announcement:
We really like this sound-file very much and it can add lots of layout atmosphere if played with the loco in a station area with loco sound otherwise off.

It is adapted from a real Birmingham New Street announcement modified to remove any train franchise names so it is generically usable for most modelling periods. Lots of echo and reverb added to give that typical almost non-directional sound from everywhere of the PA system.

If at all possible use TWO speakers in parallel this will double the
available amplifier power. The result of this is a small volume increase and a
large increase in the energy of sound delivery. It is worth removing metal to
achieve this!

SEAL the enclosures if using the 2x 23mm speakers supplied. (That means totally airtightimagine they are full of poison gas or anthrax THAT is how little air must escape for best performance).

Using two ESU enclosures will be fine although to us the BEST result will be from both speakers in a custom box and mounted very, very close together ie the rims virtually touching. This box can be made of many materials including stiff card if you find it easier. Before installing the speakers, seal all joints perfectly and paint the WHOLE enclosure inside and out with thin superglue or shellac/epoxy/varnish this will soak into the card and make a very stiff, very hard box.

Once this is done and it is properly dried, check for/fix any tiny leaks and than add the speakers using a very thin film of silicone around each speaker rim. Make sure there are NO pinholes anywhere where air can leakNone at all! They will cost clarity, volume and lower speaker power handling. Leave overnight to dry before testing sound!

F0 Lights on
F1 Sound on
F2 Horn #1
F3 Horn #2
F4 Whistle
F5 Vacuum / air release & Coupler sound
F6 Station announcement (see notes above)
F7 Rail Click (Just for fun this has been made playable without engine sound so you can use it while the loco is stopped in a station and give the impression of other trains entering the station area and crossing points etc It has also been made loud enough to be a reasonable background sound whilst the motor is running/loco moving).
F8 Brake: This is automatically applied without F8 when the loco is stopping however we added it here for manual use as it also simulates flange squeal on curves etc quite well for those who like real effects!
F9 Vacuum release
F10 Alternate horn

Please do feel free to make comment or suggestions for improvement, or tell us what or where more needs to be done.

Available now as follows: LokSound V3.5 with 23mm speaker & 8 pin plug & Deltic sound file $AU199.00 (£92.20 or 120.17 EUR - exchange rates as of 14 March 2008).

As an exclusive offer for Model Rail Forum Members only

The price is still $AU199 but we will include a second 23mm speaker OR a 40x20mm OVAL speaker and offer Free Postage worldwide!

Payment: We accept credit cards (Amex, MC, Visa or associated cards), Internationally enabled debit cards or PayPal. Direct bank deposit is available within Australia please ask for our details at time of order.

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Note: We offer a free reload service for all sound decoders purchased from us so will happily re-programme any sound decoder with this new Deltic sound file if the decoder is returned to us and $AU5.00 is deposited into our PayPal account to cover return postage (Same post cost worldwide all decoders shipped airmail).

If your sound decoder was purchased elsewhere we can still load it for you, however the cost will be $AU15.00

In either case, if the decoder does NOT have an 8 pin plug we charge an added $A5.00 as plug free decoders require added labour for connection prior to programming.

(We would prefer all payments for decoder programming costs to be via PayPal please - Email us at DCCconcepts for PayPal account details. We will of course also help you if you do not have a PayPal account please contact us for details.

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Many thanks to Richard Johnson of DCC Concepts for working with us on this project. Richard and I exchanged many email and messages on this subject and Richard has done a fine job in producing this sound 'set' for the Deltic. He is convinced that he can produce a better sound still so perhaps we will have an update in due course.

Doug Teggin
- March 2008

You can contact DCC Concepts via their website.
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