Buzz Audio Essence 500 series compressor


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The Essence is a 500 Series version of the flagship SOC 1.1 opto compressor with a similar compression characteristic. The signal path uses Lundahl input and output transformers and our True Class A discrete amplifiers. This compressor is the only compressor on the market to offer a side chain insert point in the 500 Series format. In addition, on board side chain equalisation allows you to alter the sensitivity of the compressor at high and low frequencies – another unique feature of the Essence.

The compression can be very smooth making the unit extremely useful for gently leveling a source without pumping and nasty artifacts. In contrast, the 20:1 ratio can produce heavy limiting effects when driven hard. In either case, the Essence is easy to operate and quick to achieve that “glue” typical of opto compressors. The sound through the Essence is tight and clear with some nice harmonic effect from the transformers.

Switch functions are Bypass, Side chain Monitor, Side chain High EQ, Side chain Low EQ, Link (for stereo operation with another Essence in the same rack), Side chain Insert and a switch that lets you view the module Input or Output level or Gain Reduction on the 10 segment LED Meter. 

Rotary pots set the output make up Gain and the amount of compression with Drive. Rotary selectors are used for the 4 attack and 6 release settings (including our excellent Auto modes) and the 4 Ratio settings.

Real Class-A discrete circuitry * Lundahl input and output transformers * smooth opto compression * side chain insert point * on board side chain eq * easy to use  

The Essence will physically fit all 500 Series frames and consumes 2 slot widths. The connectors associated with the first slot carry the main signal input and output. The connectors associated with the second slot carry the side chain insert send and return. The power draw of 120mA is spread over the 2 slots and within the capability of all known 500 Series racks.


Frequency Response with no gain reduction = 14Hz to 107kHz, /- 1.5dB

Maximum Input Level = 25dBu
Maximum Output Level = 27dBu
Side chain Max Input/Output Levels = 22dBu

Total Harmonic Distortion;  
Measured at 0dBu input, no gain reduction, make up Gain 0dB
100Hz = 0.1%, 1kHz = 0.015%, 10kHz = 0.002%
Measured at 10dBu input, 20dB gain reduction, make up Gain 15dB, Attack AUTO, Release 16
100Hz = 0.1%, 1kHz = 0.015%, 10kHz = 0.005%

Residual Noise = -95dB A wtg, 150ohm source Z, make up Gain 0dB

Make up Gain Range = 0dB to 15dB
Maximum Available Gain Reduction = 25dB

S/C HI EQ Boost/Cut = 8dB @ 10kHz
S/C LO EQ Boost/Cut = 8dB @ 100Hz

Main Audio Input Impedance = 20k ohms, bal or unbal
Main Output Impedance = 100 ohms bal or unbal
Sidechain Send Output Impedance = 100 ohms unbal
Sidechain Return Input Impedance = 44k ohms bal or unbal

Size = (3″Wx5.25″H). Fits 2 spaces in API* 500VPR Series rack format
Power requirements = 120mA /- 15-18 volts DC, as supplied by rack power supply.

Additional information

Weight 3 kg