Neither - they're 'electronically rechanneled'. if I may quote from my own website (it's OK, I've given myself permission):
From 1961 to 1967, Beach Boys albums were released in three formats - mono, stereo and what can best be charitably described as 'fake' stereo (the situation regarding the singles is much more straughtforward: up to and including "Bluebirds..." all BB 45s were released in mono only, as was "Cotton Fields". All the rest are in stereo). This was a process applied by Capitol to a mono master tape in order to make it sound like stereo… in theory. In practise, it usually sounded like merda. Just to complicate things further, Capitol used two versions of fake stereo. The first one, used from
Today ! up to and including
Pet Sounds, was called Duophonic, and consisted of two mono signals with an almost imperceptible time delay (measured in milliseconds) between them. The result was not unlike listening to the mono album in an empty swimming pool (
Smile would have sounded like this as well). For
Smiley Smile and
Wild Honey, a system called electronic rechanneling was used; this was basically Duophonic with knobs on, in that the time delay was augmented by having different frequencies emphasised on each channel, usually bass on one side, treble on the other. This sounded like listening to a mono album at the bottom of a deep well with a bucket over your head (just to confuse things further, the album prefix for these two - ST - indicated that they were released in true stereo. Capitol's prefix system was T (mono); DT (Duophonic); and ST (stereo). This mileage could, however, vary - the electronically rechanneled
Stack O' Tracks carried a DT prefix). The reason Capitol was forced to adopt such subterfuge was simple - from 1965 to 1967, Brian insisted on handing the company a mono album master. Prior to this, the stereo mixes handed in were the work of Chuck Britz, not Brian (who apparently tolerated the practise). The first Beach Boys album with an 'authorised' stereo mix was
Friends (courtesy of Steve Desper), and it says much for the speed of technological development within the industry that two years later, the band were releasing quadraphonic albums (OK, not exactly quadraphonic... but that's another story).
There, I think that's all crystal clear.
