Buzz Audio - Essence 500 Series Optical Compressor
The essence control circuit design is based on the Buzz Audio SOC-1.1 Stereo Optical Compressor but the main audio path utilises the BE40 and BE50 True Class A amplifiers along with high spec Lundahl input and output transformers. The input transformer is directly coupled to the Buzz proprietary Opto gain reduction element (completely passive input), amplified and then balanced via the output transformer - a very simple but gutsy signal path!
The essence control circuitry utilizes the Differential Drive Side Chain (DDSC) topology that was developed for the SOC-1.1. This system, which processes positive and negative audio waveform in seperate paths, provides the incredibly musical characteristic you will hear with this unit. The DDSC design also provides for a much faster attack time compared to most other LDR based optical compressors.
Simple side chain equalizers have been provided to allow the user to adjust the sensitivity of the compressor at high and low frequencies. In addition, a side chain insert point is provided for more complex EQ and compressor "keying".
The essence consumes 2 slots within a 500 Series rack. The input/output (I/O) connectors associated with the first slot carry the main audio path. The I/O connectors associated with the second slot are used for a side chain insert point (send and return). The insert can be switched in/out of circuit and monitored via front panel switches.