To solve this issue, EMI engineers built the RS127 Presence Box, offering 10 dB of cut or boost at 2.7 kHz, 3.5 kHz and 5 kHz. The units were in constant operation throughout the studios during recording and mixing, even finding their way into the cutting rooms.

Abbey Road's legendary Technical Engineer, Lester Smith, takes us through the Presence Boxes.

The Presence Boxes were based on an earlier Abbey Road design from 1955 and re-created as the RS 127 in 1962. It was required to add to the available treble frequencies on the EMI recording consoles, being 2.7 Kc/s, 3.5 Kc/s and 10 Kc/s which could be boosted in 2 dB steps up to 10 dB (or reduced when necessary). The grey unit had to be plugged into a purpose made rack of equipment placed behind the recording console and as it was purely passive it required a remote amplifier.

It became such a success being used on almost every recording session that more were needed and close to hand as well. So by the '60s with popular groups filling the studios, it was rebuilt into a smaller green box with ‘Siemens’ sockets in and out on the back of it and called the Brilliance Box (very '60s) with the letters engraved on front in gold.

John Lennon liked it particularly at the 10KHz mark but wished it was more 8KHz than 10KHz. So without a second to waste, our senior engineer Len Page got hold of another Abbey Road innovation - the RS 135, a box to reduce sibilance, and rearranged its components to turn it into an 8 KHz booster box. This is why it is stuck together with black gaffer tape.

The boxes were excellent for modifying the sounds of drums and guitars and also used on the echo plates and sometimes during the final cut of the discs.

Each of these boxes has been meticulously modelled by Softube. With the Brilliance Pack, today's DAW-based mix engineers can add all the air and sparkle they want, without the slightest trace of harshness – just like the world's top engineers at Abbey Road Studios have done on their recordings from the 1960s onwards.

Take a look at the Brilliance Pack.

Thank you to Lester Smith for providing us with this information.