1) Jack Bruce's bass is pretty distorted and the amp is obviously miked. There was no such thing as "going direct" back in those days. In fact, direct boxes didn't even come on the scene for another 10 years or so. I must admit, I think that miking the amp is a better way of doing things as it gives the bass player's tone some character. Direct bass tends to all sound the same.
2) Bruce's vocal is also distorted, especially when he really opens up on the B section. It has just a touch of reverb, and you can hear the compressor grabbing a bit, but it's not a bad sound in general. Also listen to all the breath noise in the vocal. If the song was recorded today, that would probably be eliminated, but it does give the vocal a sense of realism and character.
3) Bruce's and Eric Clapton's vocals are slightly split in the stereo field during the choruses
4) Ginger Backer's drums are interesting in that the pattern is built completely around the toms. You only hear a few crash cymbals in the choruses until the solo through the outro, where you also hear him play the snare with the crashes.
5) Make sure you listen through to the end, where you'll hear the songs real ending that never made the record.
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