The Altec RS 124 was the Beatles’ secret weapon, used on nearly every session but long shrouded in mystery. Though officially named Altec RS 124, it was simply called “The Altec,” with its true identity obscured by a modified front panel and extensive internal changes. Even engineers using it daily did not know it was based on the Altec 436B.
From the beginning, Altec RS 124s were critical to the Beatles’ workflow. Typically, two were inserted into the console group outputs feeding the four-track tape machine. These handled rhythm and backing tracks, while Fairchild 660s were used for vocals. Norman Smith often applied the RS124 gently to rhythm sections. When Geoff Emerick took over in 1966, he favoured the Fairchild for Ringo’s drums but used the RS 124 for bass, citing its slower attack time which preserved transients that the Fairchild lost.
On tracks like “Rain,” Emerick applied heavy compression to Paul’s bass to bring it forward. The Altec RS124 was also the go-to for guitars, both electric and acoustic, throughout the Beatles’ career. Engineers including Emerick, Ken Scott and Phil McDonald all preferred it for that purpose.
The Altec RS 124 was also vital in mix buss and submix roles. Emerick used it not only on final mixes but for reduction mixes when freeing up tape tracks. John Kurlander recalled its use for “track squashing” during four-to-four submixing. The compressor left a strong sonic imprint across mixing, mastering and cutting rooms, becoming central to the Beatles’ studio sound.
Its only notable flaw was a slight drop in low-end below 80 Hz. But it added warmth in the lower mids and smoothed the harsh upper-mid range. This made it perfect for guitars. The Altec RS 124 responded best to heavy use, with 20 to 30 dB of gain reduction enhancing its character. Light compression could cause audible pumping as the signal crossed the threshold. In later Beatles recordings, it was used boldly to shape the tone. Altec RS 124s were even moved to Apple Studios for the Let It Be sessions, alongside Fairchilds, confirming their importance.
The Altec RS 124 was not just a tweaked Altec. It was the result of a complete redesign by EMI engineers. After purchasing several Altec 436Bs in 1959, EMI found their fixed controls too limiting. Engineers Len Page, Bill Livy and Mike Bachelor began modifying the units to suit studio needs. What began as a few tweaks turned into the creation of an entirely new compressor.
Modifications included replacing the input pot with a stepped switch using constant impedance, adding a stepped output control, and installing a six-position “Recovery” switch for release time. These upgrades allowed engineers to recall settings reliably, crucial in EMI’s highly structured workflow. The recovery times ranged from 0.5 to 1.5 seconds and were marked 1 to 6, a system later reflected in other EMI gear and even Fairchild designs.
The changes went deeper. Tubes were swapped, the circuit layout was reworked, and components were updated. A new steel front panel was designed with engraved Altec RS 124 labels and serial numbers. Only the Altec badge on the meter hinted at the unit’s origin. Due to its 2U height, Altec RS 124s were often racked in pairs. This led to a stereo link feature added in 1963, allowing two units to compress a stereo mix evenly using an external cable and rear switch. Though originally developed for classical recordings, the stereo link became useful in Beatles mixdowns.
A further challenge was imbalance between the push-pull amplifier stages, which caused rumbling or distortion. Most valve compressors suffered from this. EMI’s solution was simple but effective. Len Page added a neon bulb and button to the front panel. Pressing the button triggered a low-frequency ticking sound through the signal. If the two amplifier stages were balanced, the ticking cancelled itself out. Technicians could fine-tune an internal trimpot while listening for the point of minimum tick, achieving perfect balance quickly and without test gear. This “Balance” circuit was added to all Altec RS 124s and resolved a common problem in valve design.
The Altec RS 124’s overall performance, colour and reliability made it one of Abbey Road’s most valued tools. While the Fairchild 660 is better known today, Altec RS 124s were more frequently used and applied across more elements of the Beatles’ recordings. With their EMI-only origin and limited numbers, original Altec RS 124s are now significantly rarer than the Fairchild 660. Their contribution to the Beatles’ sound remains undeniable.
