Marley used Helios console in Jamaica and the UK next to many others. In Harry J's studio where he recorded between 1974 and 1976 they used a green Helios console and in Island's Basing st. studio they had a big red Helios. But he recorded also in the Compass studio's on an MCI 500 series, just like in his own Tuff Gong where he also used an MCI. Before that he recorded in many Jamaican studio's like Federal (Altec Lansing), Studio One (RCA 5 channel mixer), JBC (also RCA), Black Ark (Soundcraft series I), Randy's 17 (MCI), Joe Gibbs (MCI 400 i thought), Supreme (some say Electrodyne, but i'm not sure), ... And jamaicans never worked with outboard pre's, they did not have the money for that next to the console containing pre's and so... But if you want a Marley bass, think a good player (Aston Barrett) on an Jazzbass and an ampeg svt and any console or pre will do it i think.