There are people doing Ambisonics 4-channel recording with electrets, so phantom is not necessarily required... Core now does second-order... https://www.core

There are people doing Ambisonics 4-channel recording with electrets, so phantom is not necessarily required... Core now does second-order... https://www.core-sound.com/products/octomic https://www.core-sound.com/products/octomic