That one:
https://www.oaudio.de/lautsprecher-selbstbau/omnes-audio/omnes-audio-exclusive-serie/omnes-audio-exclusive-6-tiefmitteltoener.html
Hexacone, long throw, rigid construction.
The Wavecor is great, but I have a feeling that it reacts sensitively on the baffle design. It might be crossed...