The Chandler Limited RS660 Compressor is a handbuilt, mono or linkable, transformer-balanced valve compressor and limiter housed in a 2U rackmount chassis with an internal power supply.
Inspired by the legendary Fairchild 660 and EMI RS124 compressors used at Abbey Road Studios in the 1960s, the RS660 is not a direct clone but a modern evolution. It distils key elements of those classic designs into a refined, purpose-built circuit designed for today’s studio workflows. Centred around a 6386 vacuum tube, the RS660 has been carefully tuned to capture the sonic character of those historic units while offering a more efficient and versatile approach to dynamic control.
Rather than replicating the past, the Chandler Limited RS660 pushes the lineage forward. It adds a unique ‘THD’ mode, influenced by the TG1 and TG12413 Zener Limiter, which allows for rich harmonic distortion without any compression. This mode enables a range of tonal effects from subtle warmth to full-blown saturation, making the RS660 a powerful tool for colouration even when dynamics remain untouched.
Designed to handle everything from vocals and guitars to aggressive drums, the RS660 is equally at home in modern production environments or alongside vintage gear. Its distinct sound and flexible control set make it a valuable addition to any engineer’s analogue arsenal.
The Fairchild 660 first arrived at Abbey Road in 1964 and quickly became a favourite for vocals and drums, famously shaping the sound of The Beatles. Its impact was both sonic and stylistic, adding presence to vocals and a unique, reverse-like character to cymbals. The Chandler Limited RS660 honours that heritage while introducing a new voice tailored for today’s recording, mixing and mastering needs.
Key controls on the Chandler Limited RS660 Compressor include Input, Output, Time Constant, THD, Compression, Limiting, Link, and selectable Output Impedance.
History
The Fairchild 660 mono valve compressor was introduced to EMI’s Abbey Road Studios in 1964 and quickly became a favourite among engineers for use on vocals and drums. It played a key role in shaping the sound of The Beatles‘ recordings. Distinct from its stereo counterpart, the 670, the 660 is renowned for its unique tonal character and responsiveness. Its effect on vocals added striking presence, while its use on Ringo Starr’s drums famously gave cymbals a reversed, almost otherworldly sound. It wasn’t just a tool — it defined a sonic aesthetic.
The EMI RS124 compressor, first designed in 1960 by Abbey Road’s technical team — Bill Livey, Len Page, and Mike Batchelor — is one of the most sought-after studio compressors ever made. Initially based on the Altec 436B, which EMI had acquired in the late 1950s, the RS124 was developed after extensive modification efforts proved the Altec units inadequate for critical recording tasks. The result was an entirely new design that surpassed the limitations of its predecessor.
The RS124 became a key part of Abbey Road’s studio workflow, prized for its warm, musical compression and ability to enhance everything from individual instruments to entire mixes. Its influence was so significant that a pair of RS124 units can be spotted in nearly every Abbey Road control room photograph from the 1960s.
