The 1960's represented a time of great advances in technology and this was as true of music recording and reproduction as in everything else. During the period that The Beatles were recording (1962 - 1969) the primary format was Mono - the installed base of mono players was massive with stereo the preserve of hi-fi fanatics and some Easy Listening and classical purists.

In fact, Mono was so important that the Beatles themselves (once they had started to take an interest in the physical production of their music) that they attended only the Mono mastering sessions. The stereo mastering was often done separately - sometimes quite a bit later and without their involvement. So for many, the mono masters are considered to be the pinnacle of audio reproduction of The Beatles - this is how they were meant to sound at the time given the importance of the single channel medium. From Please Please Me to The Beatles (White Album), all the original mixes are represented here in full, glorious mono! The Past Masters CD has been recreated as Mono Masters to properly reflect this period.

This set duplicates the Past Masters track listing with the exception of those tracks that only ever appeared in stereo. However, as an added bonus, five tracks, never previously released in mono, are included in the package. These are "Only A Northern Song", "All Together Now", "Hey Bulldog" and "It's All Too Much" all from the Yellow Submarine project plus "Across The Universe". These titles were originally scheduled for release on an EP in 1969. There is a fantastic essay in the Mono Masters booklet that explains in some detail the history of these recordings and which goes some way to highlight just why these versions are so eagerly anticipated.

With the collector in mind, both Help! and Rubber Soul discs now additionally contain bonus content in the shape of the original 1965 stereo mixes on CD for the first time, since Sir George Martin had actually remixed these for their CD debut in 1987 rendering these original mixes unavailable.All the albums (apart from Mono Masters) come in their original vinyl-style packaging reduced in exquisite detail to CD-sized format. This includes everything from the recreation of the vinyl label (printed on the cd itself) to the paper inner sleeve replete with the original text. The jackets themselves are exact reproductions of the original UK vinyl releases and since they are being manufactured in Japan, they are of the very highest quality and had the very highest possible attention to detail in the production.

Apart from the first four albums (Please Please Me - Beatles For Sale) which have been available in mono on CD since 1987, the remaining titles are making their CD debut in this format and all plus the Mono Masters set have received the remastering treatment by a dedicated team of engineers and Abbey Road studios.