As far as I understand things, to work with a conventional audio amplifier, a ribbon tweeter requires a transformer. In all ribbon tweeters that I know of, the amplifier output is applied to a step-up transformer which provide very high voltage and low current to the ribbon/magnet assembly. In this sense, ribbon tweeters work similar to electrostatic drivers.
So I have to ask, what do you have against transformers? Without them, ribbon drivers cannot work with standard audio amplifiers.