Listeners who grew up hearing everything in stereo naturally prefer stereo to mono. But most singles from the 1960s were originally released in mono. In an earlier piece I explained why some listeners prefer some mono mixes of these singles over stereo mixes. Motown singles are prime examples.

The second and final installment of Sweet Soul Music, released in fall 2009, features stereo mixes of 27 Motown singles, providing a great opportunity for mono-stereo comparisons. These were the best-sounding stereo versions of 1960s Motown singles I'd ever heard, combining thoughtful mixing and panning with superb equalization and mastering. Mono reference versions were from The Complete Motown Singles. My goal for the comparisons was simply to choose which mixes I would use for my own playlists. Here's what I heard:

There's a lot to like in these stereo mixes. Each instrument is distinct from the others with a specific location, so you can hear the terrific Motown house band – the Funk Brothers – as never before. Lead and background vocals are also distinct and clearly located in space, but they don't sound as prominent as they do in the singles mixes. Sometimes new vocal details are revealed. If you like to have the whole arrangement spread apart horizontally and highly resolved, you are in sonic heaven.

Yet for me more is lost than gained in all but a couple of the stereo mixes. In the mono mixes sounds are stacked vertically rather than horizontally. The lower frequencies at the bottom serve as the foundation. The whole band is well-balanced, solid, and full of punch. The rhythm section has a unified, propulsive quality, a crisp, strong beat. Vocals float on the surface above the band. The music rocks!

You can discern separate instruments in the mono mixes, but less distinctly, because the instruments sound softer. In the mono mixes vocals are most prominent with the band there to support them. A lyrical riff by the rhythm section often plays a key role in the arrangement; in the mono mixes you always hear that riff in the balance the producer intended. In the stereo mixes, not only are instruments louder in relation to vocals, they are also split apart spatially, diluting their rhythmic impact. It bugs me to hear the percussion instruments spaced widely apart, with drums hard on the right channel and bongos or other percussion hard on the left. This split tears apart the coherence of the punchy rhythm section in the mono mix, leaving a gaping hole in the center.

I also dislike stereo versions in which the relative volume of instruments is altered so much,  amounting to a remix. For example, in "Heat Wave" the band plays an exciting, propulsive instrumental introduction. In the stereo mix the sax is boosted on the left channel to the point where it seems to drive the whole rhythm section. It's a pretty cool sound, and I'm happy to have it in my collection as a remix. But it's not the way "Heat Wave" was mixed as a single, not the way I've heard it hundreds of times before, and not the way I want to hear it interleaved with other songs in a playlist. By this defiinition, about half the stereo mixes (not only Motown songs) from Sweet Soul Music should be called out as remixes.

These differences are magnified listening through headphones versus loudspeakers. With headphones, the "hole" in the center is emphasized, making the lack of spatial coherence impossible to ignore. With loudspeakers the effect is more subtle. Also, my loudspeakers convey much more lower bass energy than my headphones which, in the case of Motown singles, plays a significant role in their emotional impact.

Whether or not you agree with my preferences, please feel free to comment about your own listening experiences.