Looking at the release dates of the albums, there was a gap between The Brass are Comin' in 1969 and Summertime in 1971. It makes me wonder if the album was indeed in the can for a year or two (I could see it being a 1970 release), perhaps to keep some new Herb Alpert "product" available while he was taking a break. Or it could have been a couple of sessions rounded up for the album; some of the tracks sound different than the others (from a technical standpoint), making me think it could have been a couple of different recording dates. Then there is a track like "Last Tango in Paris" that pretty much came out of left field, appearing first on the Foursider anthology.
I also am curious about when Herb switched from using Gold Star Studios to A&M's own studios. The Gold Star recordings have that well-known reverb chamber in use. Yet, for most of those early albums, Gold Star only was capable of 3-track recording. What I hear on Summertime and even Warm is too complex to have been done at Gold Star, likely needing eight tracks to record what we're hearing, and (aside from that dreaded CSG processing) The Brass Are Comin' has a cleaner sound to it also, along with those orchestrated bits.
I also am curious about when Herb switched from using Gold Star Studios to A&M's own studios. The Gold Star recordings have that well-known reverb chamber in use. Yet, for most of those early albums, Gold Star only was capable of 3-track recording. What I hear on Summertime and even Warm is too complex to have been done at Gold Star, likely needing eight tracks to record what we're hearing, and (aside from that dreaded CSG processing) The Brass Are Comin' has a cleaner sound to it also, along with those orchestrated bits.