Madonna

Madonna utilized the Roland VP-9000 on her song "I'm So Stupid." In reference to this track, it was noted: "I am thinking of a track like ‘I'm So Stupid.’ That is one of the most innovative tracks on the album. The vocal starts very gently; then, I freeze it using the Roland VP-9000. It is the only machine that can do this. It is not a sample loop; it is a freeze. When she sings ‘Aaaaaahhhhhh,’ the vocals freeze. It is a gently modified track. It sounds natural, but it is not natural." This information is supported by the article titled "COVERT Operation" from Remix Magazine.

Madonna used the Universal Audio LA-2A compressor/limiter on her "American Life" album. As noted in the article "COVERT Operation," the production team stated, "We used mainly analog compressors on the vocals, sometimes very cheap or midbudget stuff, recorded with a Sony G800 tube mic, a Neve 8081 preamp and an LA-2A compressor/limiter. But everything is about the setting, my friend."

Madonna utilized the AMS DMX 15-80S Digital Delay on “Hollywood” and “I'm So Stupid.” "Two machines were used for the extensive vocal editing in “Hollywood” and “I'm So Stupid.” Madonna preferred the Antares Auto-Tune plug in; Mirwais chose an AMS 1580 S-DMX pitch shifter."

Madonna used the Yamaha 02R mixer in the production of her song "Hollywood." This is confirmed by Mirwais, who worked on the track and stated, "I had to find exactly the right frequency on the Yamaha O2R mixer. It was very hard to find the right kick, too, because if I chose something bigger, the track would have sounded like an average club track."

Madonna is confirmed to use the Roland RE-201 Space Echo, as evidenced by a photograph depicting her in a recording studio with producer Stuart Price, where the gear is clearly visible in the background.