The essence is a True Class A Optical Compressor designed to fit the API* 500 VPR Series rack frames offering a great feature set in a compact package. The essence will find application with those seeking a musically transperant compressor for all tracking and mixing tasks, and it sounds particulary outstanding when processing voice and bass tracks. The essence - the Heart 'n' Soul of your next recording!

The essence control circuit design is based on the Buzz Audio SOC-1.1 Stereo Optical Compressor but the main audio path utilises our 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.

Rack Compatibility
The essence power consumption of 120mA is higher than other 500 series modules, but because this demand is spread over two slots (60mA each) it should work fine in all available racks. For more information on linking two essence units, please read this.

• API* 500VPR Series rack module format - plug in and play!
• Advanced analogue technology - not a clone or copy of products from the past.
  
• Powerful fully discrete hi-bias, wide bandwidth, differential Class A amplifiers.
• Passive transformer coupled input, transformer coupled output
• Side chain insert point
• Side chain monitor selector
• On board side chain EQ
• Unique Differential Drive Side Chain design
• May be linked to multiple essence units within one rack, more info
• Switchable 10 segment VU meter