djd100":2qlp16hq said:
Am I to believe then that they're typically just adding some bandwidth limited early reflections/room tone to their IR's.
That would be the most likely result. If a really long cab IR contained no room reflections, then Ultrares would include a longer - but band-limited - decay tail. In the case of guitar cabs, this tail is so low in level as to make an inaudible contribution to the sound of the IR.
Back when the first-gen Axe-Fx only had 512-point cab IRs, I devised a way to double the length by splitting a cab IR in half, applying the appropriate delay to the tail, and mixing the halves together in the Axe. Direct A/B comparisons revealed subtle but reliabily detectable differences. Shortly thereafter, Cliff found a way to double the length of the IR that could be processed to 1024 points. Based on the subtlety of the difference between 512 points (~10.5ms) and 1024 points (~21ms), I stated at the time that further increases in the size of IRs would yield negligible benefit.
I will add that many record guitars with a blended room mic(s) in a damped environment so perhaps this is what they're attempting to replicate with the new IR's?
Cliff's original justification was that you needed the longer IR to hear low-frequency detail in the response of a cab, but he posted a graph that included obvious effects due to room reflections. He later modified his stance to the one you speculate ("Embrace the room"). If that's really the goal, then "Ultrares" is definitely not the way to achieve it....
