I compare the two classic versions of the Celestion G12H30 Greenback 55 Vs 75. I'm putting 4 of each in two straight Marshall 4x12 speaker cabinets from 1971. All the speakers are from 1971 as well. 55 and 75 refers to the resonant frequencies of the paper cones. The 55Hz version is the speaker Marshall used in their '100' model 1982cabs and the 75Hz version was used by Orange and Laney for instance.
Gear: 2010 Gibson LPC 57
1976 Marshall 1959 DF100VH modded
2x 1971 1982B cabs with
4x '71 G12H30 55Hz Greenbacks
4x '71 G12H30 75Hz Greenbacks
Close mic Unidyne IV 548
Room mic Beyerdynamic M160