Eckmiller passive fader info and purchase advice needed

Hello everybody,

I am starting  a console project which I will start a dedicated thread for soon

I have been hunting for faders and I am pretty sure I will use some passive type, transformer balanced

The models I have found so far are

Eckmiller W66
Eckmiller W68
Eckmiller W85
Eckmiller MR90
Neuman W444

I don't really know the difference, and information on the web is not available

I have found some pictures that can maybe tell something to a more expert eye

Basically I would like to know which model is the best in terms of sound and construction quality

I can see from the pictures W85 and W68 are pretty different, and read some comments that the 85 is a better fader

MR90 looks similar to W68 from the pictures

W444-STB is the only one I found a schematic for

What do you think ?

Eckmiller W68

Eckmiller W85

Eckmiller MR90

Neumann W444-STB

Neumann W444-STB schematic

Looks like the W85 is the only one that uses precision resistors (a lot of them!) instead of a carbon or plastic fader track.  This might make them more accurate from unit to unit.  The W444 is obviously active, not passive, so that has it's own set of plusses and minuses.

The Neumann Faders are all active.

You don't want to go with the STB version. It doesn't have a transformer balanced output AND is harder to source.