DCC sound decoders

This section is to put down some information about DCC decoders for large scale that have motor control and sound.

The contenders are QSI, Zimo, ESU, and Massoth.

The 21 pin was originally an ESU / Marklin thing and was created without much thought for other subests of pin-out requirements. The motivation was the existence of sound plus the new marklin 3 wire motor....

The 22 pin was actually initially proposed by an unusual Mfr combination of, from memory, Digitrax and Fleischmann.

Actually, the connectors themselves are identical (both are 22 pin actually) BUT

(1) the "blanking/polarity pin" is in a different place
(2) The 21 pin is female in loco and the 22 pin male in loco (or Vice versa)

I must admit that I also raised an eyebrow at the 22 pin concept which is called PLUX 22.

However...on considering it:

It has a much more sensible approach to other needs, such as "subsets" of connections as the pins have been more sensibly arranged.

ie: Subsets that will work with PLUX 22 but not 21 pin.

new possible 12 pin (existing sound decoder plus a couple of added Fn plus Speaker ec)
8 pin (as per existing 8 pin wires / new connector of course)
6 pin (as per existing 6 pin / new connector of course)

Whereas the 21 pin is a bit more of a problem for other than "ex factory" installs.

I predict that the 22 pin will actually win out in the end and the 21 pin will actually be localised on some brands of EU locomotives.

I predict too that for a long time, 8 pin will still dominate...


I'd not be surprised to see Bachmann go to the 22 pin soon - perhaps apart from loco's with ESU decoders factory fitted. (which is the only reason they use 21 pin now anyway)

Motor control

current rating continuous

current rating peak





Lighting outputs


Other outputs

Sound system


high power

smoke units


regulated voltage




Trigger inputs






Other inputs


Sound files

Number of steam

Number of Diesel

Number of electric

Number of other




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