A detailed review of the Next18 (NEM662) interface. Does it deserve to be NEM651’s successor?

Plux12? Not so much…

My article complaining about the multiplication of new digital interfaces in N scale model trains in Europe has had quite a lot of success (“DCC plugs overview (they’ve gone crazy)”). My criticism stays intact: European manufacturers need to stop meeting in closed rooms and inventing multiple interfaces to replace the NEM651, thereby segmenting the market.

That said, there is one fact I don’t argue. The NEM651 digital interface is old, does not offer enough possibilities, and needs a replacement.
In my original post, I thought the Plux12 interface was a nice compromise. After trying this interface on a Piko railcar, I realized the Plux12 was not so good. The good old pins (placed vertically) require a lot of vertical room in an N scale train:

Zimo - MX623P12 Dcc Plux12 Decoder

Plux12 Decoder (Zimo – MX623P12)

Meet Next18

I recently decided to try out the Next18 interface (also called “NEM662”), which I originally criticised.

What changed my mind? Some manufacturers (in my case, Doehler & Haass) have released adapter boards for this interface, which means you can equip old models with the Next18 interface, and then just plug in a compatible decoder. Installing an interface, instead of soldering the decoder, is a good future proof strategy. Of course, this is all manual DCC conversion work.

Next18 (NEM662) - Interface adapter boards from Doehler & Haass

Next18 (NEM662) – Interface adapter boards from Doehler & Haass

There are also some store-bought models with the Next18 interface. Although, because of the segmentation, not all manufacturers are on board. One of these manufacturers is Liliput (now Bachmann Europe PLC).
Update 2014-07-29: Next18 is gaining traction. The German magazine Modellbahn Digital has announced that Arnold will start using the Next18 digital interface on its new models.
Update 2016-01-03: Next18 is conquering the UK. Graham Farish (Bachmann Europe Plc) is releasing its first Next18 models this year!


The Next18 interface boasts a good number of potential connectors in comparison with the old NEM651:

Next18 (NEM662) vs NEM651 DCC interface

Next18 (NEM662) vs NEM651 DCC interface

Of course, remember: the fact that an engine has a specific digital interface does NOT mean that all functions outputs are actually used and connected inside the engine. For example, Liliput trains already equipped with the Next18 interface do NOT use the full range of 6 auxiliary functions.

First impressions

“Testing” a DCC interface does not really make sense. So here are instead my first impressions, opening the box from the Doehler & Haass adapter boards for Next18, and the ESU Loksound Micro v.4 sound decoder in its Next18 declination.

Next18 (NEM662) - ESU Loksound Micro v.4.0 + Doehler & Haass Adapter board

ESU Loksound Micro v.4.0 + Doehler & Haass Adapter board

The decoder is a sound decoder, so of course it is bigger than usual decoders. However, the Next18 does not seem to impact the overall size:

Next18 (NEM662) - ESU Loksound Micro v.4.0

Next18 (NEM662) – ESU Loksound Micro v.4.0

Once connected to the adapter boards, the vertical size remains reasonable. Actually lower than Plux12 pins:

Next18 (NEM662) - ESU Loksound Micro v.4.0 + Doehler & Haass Adapter board

ESU Loksound Micro v.4.0 + Doehler & Haass Adapter board

This all seems very promising, and much smaller than what I had expected. I will be testing the interface by converting a train of my own.

One big drawback (customer confusion ahead!)

There is however one big issue with Next18: the NEM662 norm defines 2 interfaces:

  • Next18 for decoders without sounds
  • Next18-S for decoders with sound

In both cases, the Next18 plug/interface is exactly the same. However, the room to be left free for Next18-S decoders is bigger. Added to this, 2 pins are reserved to connect a loudspeaker with Next18-S.

It gets more complicated than that. A locomotive with a simple Next18 (no sound) interface will actually be able to accept a Next18 sound decoder, if the latter has adopted the smaller Next18 dimensions (which is the case for the CtElektronik SL76Next18). All you’ll have to do is connect the loudspeaker correctly.

Conclusion (for now)

Next18 may be the next best thing for European (and hopefully international) N scale models. It remains very small, but has plenty of connection options.
The Next18 vs. Next18-S possible confusion proves that German and Austrian train manufacturers still employ too many engineers and not enough marketing people (actually thinking about being “customer friendly”). That drawback, however, is not that serious.

I personally hope that more and more manufacturers will start selling their engines with the Next18 digital interface.

I always try to be fair and square when giving grades, see the details about the evaluation criteria here !

Reminder: I am a hobbyist and these articles only represent my personal views. I am not receiving any compensation, in any form, from the brands or stores mentioned here. The product names, marketing names, and brands mentioned here are the property of their respective owners.

This article was written with the N scale in mind
Although some of the content is relevant for other model railroading scales, if you are using another scale, additional or more accurate information might be available elsewhere!

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