For this DVD release a great deal of effort went into effecting a drastic renewal of both the video and audio of the Neon Genesis Evangelion TV series.
The focus of the renewal plan for the audio was building 5.1 sound. The sound for the Evangelion TV series was produced in 2.0 stereo. For this renewal, rather than choosing to use specialized software to mechanically split the 2.0 stereo sound into 5.1 audio, the three elements that make up the sound: dialogue, music, and sound effects, were each remapped for every episode. This work required a tremendous amount of time and in fact took almost half a year to complete. Some of the additional recorded dialogue is material that was intentionally left off the 2.0 stereo recording, even though Director Anno originally planned for it when the show was being produced, because it was surmised that including those lines would be information overload, making everything harder to hear. In other cases, there was dialogue added to tighten up certain areas that had too little information in terms of the audio. Specifically speaking, the majority of these lines are reports and announcements from the NERV staff at the command center. Others include background crowd noise in school scenes and announcements at train stations. Of the cast members who participated in the additional recordings, the only original cast member is Megumi Hayashibara. And her part was to play the super computer, MAGI, not Rei Ayanami. In other words, of the characters with names, the only one to have additional dialogue was the MAGI.
The fundamental concept behind the sound renewal was to respect the original. With regards to musical pieces, the original materials were mixed down into 5.1 sound, but musical selections were not made anew, and the additionally recorded dialogue was to augment the already existing voice recordings basically using the original recordings as is. In other words, it was polished into a higher quality product by adding positive elements while still making the most of the original material.