So I was at a Bob Weir show the other night and I've been since baffled by their bassist Robin Sylvester's sound. From what I saw, he was running a Gibson Thunderbird into an unknown head, and from there into 2 Mesa cabs which could have easily been 4x10 or 1x15, or a combination. I couldn't make out a manufacturer logo or anything on the head, but I know it was single channel. And thats where the question comes in: how was he able to get clean, clear, crisp hi-fi-like highs (open D and above), and through the same setup durring the same song (any song), get crazy fat, dub-like lows (E and A strings) the likes of which were almost unbearable? I just can't get this one through my brain without thinking "There's got to be some special electronic something there that I didn't see, some crossover or something..." Anybody got any ideas? I loved the sound and would like to be able to recreate it to some extent. Thanks all!