I make no secret of my love for well-written, well-performed, well-produced pop songs, and ABBA were expert at all three. This Guardian article ranks their UK singles, and the top 5 are spot on. SOS is the perfect pop song, and is on my list of top 5 all-time favorite singles.
The acoustic guitars that come in with the chorus is a sound that I strive for in my productions, and I have spent way too much time digging around on the internet, searching for clues about how they achieved their unique vocal sound.
I did suss it out. I know exactly how they did it. (I'm not telling, by the way!) I watched many interviews, in Swedish, with the ABBA engineer, along with live recording sessions to learn how they made their secret sauce.
At least 80% of the sound is down to Frida and Agnetha's voices, and the way they sound together. The other 20% will die along with analog recording, or will it?