TRIPLE Tracking
The secret to ABBA sound is TRIPLE tracking, using the vari-pitch.
It was revealed in the Mama Mia! documentary they have been aring recently.
Bjorn (or was it Benny?) is in the studio with their old engineer, pulling up tracks.
They would record the whole band (bass, drums, guitar, piano) once,
then record the band as a double, with the vari-pich slightly high
then record the band as a triple with the vari-pitch slightly low.
It's the MONO mixing of these that give you the ABBA sound.
I've tried this with acoustic guitar, and it sounds great. More interesting than mere "chorus" effect on a machine.
- Three takes, doubling what you have played.
- Vari-Pitch high and low (to taste)