There are few groups as obsessive than guitar players on the quest for ultimate tone. We buy new guitars and amps, of course, but we also audition effects pedals, strings, pickups, speaker cabinets, and speakers. At least, that's what we do in the physical world.
Now, you can also trade out speakers in the digital realm.
All of the Celestion Impulse Response options are downloadable from the Celestion Plus website and are recorded in a professional recording studio with a slew of microphone-placement options. The IR mics used for close-miking perspectives were a Royer R-121, a Sennheiser MD421, and a Shure SM57. For room mics, the Celestion recording team employed a pair of Neumann TLM 107s. Microphone placement for each Celestion IR speaker was set to produce six different timbral variations for each close mic: balanced, dark, dark 2, bright, fat, and thin. The room mics offer a left, right, and stereo perspective, and open-back cabinet models offer a bonus "SM57 Rear" option. Furthermore, you get a selection of multiple-mic perspectives:
R-121/MD421
R-121/SM57
MD421/SM57
You'd have to find a studio with a great room, experienced engineers, and a staff not too lazy to try every available mic and mic-placement arrangement to get this level of speaker-tone options to evaluate.
Lastly, you have a bounty of Celestion speakers to choose from, including the GM12M Greenback, G12H Anniversary, Celestion Blue, Vintage 30, G12H-150 Redback, and more.
You can download speaker IRs individually ($11.99), or by the Collection ($29.95; a 40-percent savings over the individual