Unbelievable stuff

Just noticed Padraig's tenor regulator in the first video has a high d, which is new to me. Is that at all typical? I'm curious if the reg needs special construction to accommodate this, or if an extra key can just simply be tacked on to a typical reg.

Not typical. I doubt if it's simply a matter of adding an extra key. Drilling the tone hole for the extra key would alter the tuning of all lower notes on the reg, so their positions would probably have to be recalculated. But I'm speculating. Any high priests of pipe-making willing to chime in?

The bass reg keys also looks non-standard. Either there's an extra key or the C key is elongated.

_________________
PJ