The producer doesn’t usually put up the money – the record company does.
Generally, a producer is one part arranger and one part psychologist. Unlike an engineer, the job of a producer is not so much a technical one: the producer usually works with a tracking engineer to make sure the sounds get onto tape cleanly. Thus, a producer isn’t so much of a ‘knob-twister.’ In fact, I’d say a producer could be almost deaf and still do a good job as a producer. As Dusty said, the producer will make sure the band is performing well. If need be, the producer will give the band a little motivating ‘push.’ Also, the producer often acts as a go-between to the record company (the record company always seems to want to know what’s happening with all their money).
The job of audio mixer is a far more technical one. The mixer comes in and mixes the album months after the band finished tracking the album. The mixer, like the mastering engineer, works in relative isolation. The best mixer will have good ears and a familiarity of the most recent mixing techniques. OTOH, a mixer is somewhat like a arranger/producer in that he or she decides the loudness of the instruments in relation to each other, the amount of reverb and other effects added to the mix, and the placement of the instruments/effects in the soundstage. As I understand it, the mixer will often weed out some of the redundant recorded tracks (e.g., if the multi-track tape has 30 guitar tracks, a mixer might simply mute some of the redundant ones). Today, with hundreds of available tracks, ‘over-tracking’ can be a problem.
The final key to the puzzle is the mastering engineer. Most modern mastering engineers are totally deaf slaves of the record company. Almost all of them should be flogged.
