A quick way to convert textures to .tx is to use the TX Manager.

A tutorial that shows the workflow involved when working with .tx files can be found here.

Usage

Parameters

 

There is no texture filtering when not using mipmapped textures. This can cause some differences, more notably for emissive maps and displacement maps.

Do not linearize textures used to drive scalar values as you will lose precision values.

The maketx utility is available in the MtoA plugin folder. In Windows this would be:

C:\Program Files\Autodesk\Arnold\maya2020