Concentric drivers

I mean if you setup a big speaker on a trampoline and crank up the volume real high, maybe there could be some measurable doppler effect. But there's really not much specifically about a concentric driver to be concerned about.

The woofer does act as a horn extension for a Tannoy's tweeter, but it's never been a topic of discussion or concern, to my knowledge. 

I agree with Mulveling, (whose system I would love to hear), Tannoys have been recognized as one of the best-sounding speaker systems on the planet for almost all the years I've been alive.

I don't care if there is some Doppler effect happening, I love their sound, and that's what matters to me.

Regards,

Dan

The Ohm  acoustics speakers should not have doppler affect since all frequencies from the driver are coherent from one source and align in parallel as they leave the driver due to the driver alignment and method of transmission from back of the speaker

The most recent Thiel concentric drivers use a rippled cone area to offer additional strength that allows for flat profile to mitigate the doppler affect that would otherwise be introduced.