It is generally well known that optical compressors are an excellent choice for compression on low frequency sounds, and the Buzz Audio SOC-1.1 is a great example. This piece is an excellent choice for tracking bass guitar, but will also find application on vocals and other general compression tasks.
The SOC-1.1 Audio Compressor is based on the Light Dependant Resistor (LDR) technology from the past, but incorporates a unique "Differential Drive Side Chain" topology and our own Opto module design to create a more adjustable and faster compression characteristic. Gain reduction is totally passive, there are no distortions introduced from semiconductor elements and the signal path is kept to a minimum. LDR selection and matching within a stereo unit ensures accurate tracking compared to vintage LDR designs.
A common problem with older opto compressor designs (and many modern ones!) is the inherent slow attack time of the LDR elements, which can cause sibilance problems and audible "pumping" effects. A special "speed up" circuit within the side chain section of the SOC-1.1 effectively reduces the attack time to less than 1mS (in fast attack mode). We believe this is the fastest attack time of any LDR based compressor on the market today and makes it suitable for stereo mixdown (2 buss) compression tasks.
All the features available on the SOC-1.1 allows users to create many different flavours of compression, from full on squash to just gentle levelling. A very useful piece of kit destined to become a classic.