Mystery to me anyways.... here's what I mean-- I happened to get Back in Black on the radio tonight, I was listening fully knowing that the guy's tones are based in cranked amps.. There's the overdrive/distortion of course. But there's something else - - - what is the 'pleasing' trait of this type of sound.? Pleasing, meaning, loud with distorted character but not mangey or icepicky. My amateur guess is, that its the Compression, at a certain frequency. Naturally occurring. I know that Compression is the really obvious thing about it but, the frequencies that are affected....thats what I'm interested in. To my ears it was flattening the 1.5k-3k area in my very uneducated opinion. Am I close? This just dawned on me tonight after a few years with my first ever tube amp. They're getting the girth and the liquid sort of volume without the harshness. I know the mixing engineer would use some EQ anyway, even on Angus & Malcolm. But Am I close.? And, are there some power tube brands (I'm interested in EL34/6CA7) whose character is exactly this,,,compressing at a certain point in the frequency spectrum compared to some other brand.. Am I making sense? Thanks if you can help.