I copied this from another forum, and thought it was right on...and very informative. I own both styles of the JCM800 1936 plywood cabs, and have owned the JCM900 versions, and I concur with this observation: I've gone through six 1936 cabs and done multiple side-by-side comparisons using the same set of speakers. I find the earliest version of the 1936 cabs to be the most toneful - although these are JCM800 era, this first version was the exact same size as a 70s Marshall 2x12 combo and is all plywood construction (some even had plywood backs) and sounds great. Marshall changed the dimensions of the JCM800 1936 cabs in the 80s to the current specs and changed from one handle on top to two handles - one on either side. When Marshall moved into the JCM900 years, they changed the 1936 cabs to all particle board construction which I feel hurt the tonality of these cabs. I've preached about the differences in these cabs in the past but in many comparisons, here's what I find to be the tone differences: First version JCM800 1936 - to me, these have the most balanced tone with the most present and lively mids. Good low end that is clear and musical. Highs are smoother than JCM900 version. Second version (current dimensions) JCM800 - Still nice mids. The lows are extended and more present and still musical. The highs are relatively unchanged. JCM900 version (particle board) - The lows are even more extended but become a bit boomy and less musical - more thump, less articulation. The mids become a bit sterile sounding and are less present. The highs move more towards harshness.