"switched-on brandenburgs" is a collection of all six of bach's brandenburg concertos performed by carlos on her moog modular synthesizer. concerti #1, (most of) #2, and #6 were recorded specifically for the album. concerti #3, #4, and #5 had been previously released on "switched-on bach", "the well-tempered synthesizer", and "switched-on bach ii" respectively (though the second movement of #3 was re-recorded for this release). the first movement of the second concerto had been recorded for the album "by request", released in 1975, however an updated mix is on this album.