Spogg wrote:on one he seems convinced the instrument would have been used in ceremonies and celebrations, and maybe religious contexts, as well as warfare.
As much as I love romantic dreaming, it must be clear that the Carnyx was not a musical instrument! It is possible that it was used on other occasions than warfare, but never in terms of music. Just in terms of signals.
You had the bad luck to only base your opinion on videos by John Kenny. I say bad luck, because he is a highly trained fulltime musician (who btw makes a lot of money by selling his carnyx music), not a historian. And especially not a soldier in war, having to blow into that thing while protecting against arrows.
1. The only proven facts are, that the carnyx was used during battles to make frightening noises. And that the carnyx was used during an initiation rite, where warriors became knights. You can see this on the cauldron of Gundestrup.
2. Kenny uses a modern mouthpiece (which is movable). Such a thing doesn't exist for the carnyx. At least not for all of the found ones and those on the cauldron.
3. Kenny uses a technique known as Clarinspiel/Clarino (I couldn't find a translation for it), whereby because of the complexity of some composer's pieces the musicians had to train hard and long to produce notes that the natural horns in the renaissance couldn't produce directly, by shifting their resonant cavity in the body and using complex lip movements. This technique was invented in the early 16th century. Not 100 b.c.
4. Without a movable mouthpiece, a Carnyx isn't tunable. Several Carnyx players (like during the initiation rite) were never in tune.
I also saw the video from 2016, where he describes a use outside of a war horn. He never speaks of music, but of voices that could be potentially impressive even on occasions where a battle is not involved.