Guitar Speaker Comparison - Modern Celestion G12M-65 Creamback Vs 1970 Pre Rola G12M-25 75Hz Greenback with a Pulsonic Cone. 1977 Marshall JMP model 2204 into a 1986 Marshall 1x12 model 1933 with a 2016 Epiphone Flying V Korina. Close mic Sennheiser MD421 U5, Room mic AKG C414BXLII OMNI at 10 feet. Both speakers are broken in.