Field effect transistors, also known as FET, are a type of dynamic audio effect. FET compressors are designed to maintain more transients, so they add an extra punch in contrast to the variable. These extra punches are known as mu and VCA compressors. Generally, the slowest attack time on the FET compressor is much faster than the fastest attack time variable mu compressor. The first field-effect transistors came about when small transistors began to replace larger tubes. Field-effect transistors are very warm and rich regarding sound character. In a FET compressor, the sidechain is a result of the gain reduction phase, hence, it is extremely program dependent.
A popular FET compressor design was the 1176 amplifier by UREI, which gained its popularity because it offered extremely quick attack and release times. It also offered a wide range of sound characters that varied between subtle, near-transparent compression to all-out drive and distortion. The 1176 limiting amp used artificial reverberation with echo chambers for commercial use, and its selling point had an extremely fast attack and release times. This audio compressor added character, attitude and vibe to everything that ran tough its circuits. The 1176 amplifier was physically unique, so it was often used with the compressor turned off, just for the added appearance.
The 1176 amplifier had unique features like push-button selectable ratios for both compression and limiting. It also had an all-buttons-in mode that allowed all the ratio buttons to depress simultaneously, achieving a peculiar sound. The device’s amps and transformers provided a unique quality to anything that went through them.
After the 1176 amplifier was launched, there were many attempts to replicate the original version. The Universal Audio version, known as UAD, was one of the closest replicas. In this version, the signal is perceived after gain reduction and used to enhance stability. The UAD uses feedback in each of its amplifier phases. For the replica to be exact, UAD had to replicate the original integral output transformer, which offered a feedback signal to the final line output amp circuity.