Prior to the mid-1950s, automatic gain control devices were not to be found in Abbey Road's equipment collection. By 1955, EMI had recognised the need for a device to stop - or 'limit' - extreme volume peaks, while leaving the 'normal' material unaffected. As a result, the research department at EMI developed a limiter known as the RS98; however, less than a year later they had returned with a "new and improved" design, developed in response to the staff's praise for the Fairchild limiters some had seen and heard used at Capitol Records ( EMI's sister American label). This new version, the RS114, was a mono limiter-amplifier with a delay line ( the delay was not an echo-type delay but was the early description of what we now know as "attack" time).

The RS114 was developed by Mike Batchelor, who also designed several other great devices that were used on many Beatles' records. In 1956, EMI authorized the construction of six of these RS114 Limiters; one for each control room, two were dedicated to cutting rooms, and one for remote recordings. In 1957, six more followed.

Although originally designed with disc cutting in mind, the new limiter turned out to be a significant addition to the studios as well; pre-dating the Altec compressors by several years. The RS114 proved itself to be a useful tool on pop recordings and saw a great deal of use. Beatles' engineer Norman Smith was particularly fond of this limiter, and a pair of them could be typically found in a rolling rack next to the console(s) when he was working a session, not only for The Beatles, but for other pop groups that were also signed to EMI at the time. The limiter was used on both Eddie Calvert's trumpet and Ruby Murray's voice - two distinctive sounds in totally different ways. It was also a significant component of The Beatles' 1962-1964 period. It shaped much of the vocal and guitar sounds on The Beatles' first three albums - Please Please Me, With The Beatles, and A Hard Day's Night, as well as all of the group's singles well into 1964. There were some engineers who didn't share Norman Smith's fondness for the RS114, however. Malcolm Addey and Stuart Etham noted that the valve circuits would often drift out of calibration, causing some noticeable artifacts on some particular sounds. Stuart Etham commented that, "RS114 was not my favourite piece of equipment, you could hear it operating, chopping off loud forte passages of music, it sounded like chopped-off toothpaste".

The RS114 had features that are still very common on modern limiters; input and output levels, attack and recovery time adjustments, and an in/out switch. The main problem with the RS114 was its instability. It was a complex design for the time, using push-pull amplifier stages - valve circuits that required exacting adjustments to create a balance between two opposing sides.

If not balanced properly, the RS114 reacted strangely; the meter on the front could be switched to read the voltage levels of the valves, and additional switches selected which valve current was being read. There were five balancing adjustments to make, and 14 valve readings to verify - certainly quite an extensive checklist for a single piece of equipment. Malcolm Addey said that, "It was a real pain in the neck to keep all those push-pull circuits in balance for the length of a session. In comparison to later limiters, such as those from Fairchild, the RS114 was not "exceptional", but it served its function well in an era when there were so few options..."

The above is taken from an excerpt from "Recording The Beatles"; © 2006 Curvebender Publishing / Kevin Ryan & Brian Kehew

Continuing the tradition of EMI Limiters started in 1954 with the RS114 tube limiter and the 1968 RS168 Zener Limiter, the Chandler / Abbey Road TG12413 Zener Limiter is the ultimate TG limiter issued in celebration of the 75th birthday of Abbey Road Studios, 15 years ago.

The TG12413 Zener Limiter was conceived by Chandler Limited designer Wade Goeke and is based on the vintage EMI circuits used to record The Beatles and Pink Floyd. The Zener Limiters were also part of the 1969 TG12345 console channel and the 1974 TG12413. This newest version borrows from the RS168 Zener Limiter and TG12345 console strip to make a new full-featured and flexible unit for modern use. Find out more.