"At the start of the restoration process, engineers conducted extensive tests before copying the analog master tapes into the digital realm using 24-bit/192 kHz resolution and a Prism A-D converter. Dust build-ups were removed from tape machine heads after the completion of each title. Artifacts such as electrical clicks, microphone vocal pops, excessive sibilance, and poor edits were improved upon as long as it was determined that doing so didn’t at all damage the integrity of the songs. Similarly, de-noising technology was applied in only a few necessary spots and on a sum total of less than five of the entire 525 minutes of Beatles music. Compression was also used sparingly and only on the stereo versions to preserve the sanctity of the dynamics.

In cutting the digital masters to vinyl, stringent safeguards and procedures were employed. After cutting to lacquer, determined to be warmer and consistent than cutting to DMM, the next step was to use the Neumann VMS80 cutting lathe at Abbey Road. Following thorough mechanical and electrical tests to ensure it was operating in peak condition, engineer Sean Magee cut the LPs in chronological release order. He used the original 24-bit remasters rather than the 16-bit versions that were required for CD production. It was also decided to use the remasters that had not undergone ‘limiting,’ a procedure to increase the sound level.

Having made initial test cuts, Magee pinpointed any sound problems that can occur during playback of vinyl records. To rectify them, changes were made to the remasters with a Digital Audio Workstation. For example, each vinyl album was listened to for any ‘sibilant episodes.’ vocal distortion that can occur on consonant sounds such as S and T. These were corrected by reducing the level in the very small portion of sound causing the undesired effect.

Similarly, any likelihood of inner-groove distortion was addressed. As the stylus approaches the center of the record, it is liable to track the groove less accurately. This can affect the high-middle frequencies, producing a ‘mushy’ sound particularly noticeable on vocals. Using what Magee has described as ‘surgical EQ,’ problem frequencies were identified and reduced in level to compensate for this.

The last phase of the vinyl mastering process began with the arrival of the first batches of test pressings made from master lacquers that had been sent to the two pressing plant factories. Stringent quality tests identified any noise or click appearing on more than one test pressing in the same place. If this happened, it was clear that the undesired sounds had been introduced either during the cutting or the pressing stage and so the test records were rejected. In the quest to achieve the highest quality possible, the Abbey Road team worked closely with the pressing factories and the manufacturers of the lacquer and cutting styli."