The Buzz Audio 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.
A very versatile optical compressor for 500 series frames with unique features including our famous opto sound.
Audio path quality
The input is coupled directly to our proprietary light dependant resistor gain reduction element via a Lundahl LL1540 input transformer. This is followed by a discrete signal path using our class-a BE40 amplifier for gain make up and the BE50 high current line driver to excite the Lundahl LL1517 output transformer. All this creates a very warm low end sound along with extended top end clarity.
The essence is the only 500 series compressor (that we know of) to feature a side chain insert point so you can apply equalisation to the compression characteristic to control certain parts of the audio spectrum. The insert can also be used to "key" the compressor from another sound for all sorts of creative pumping effects. In addition, there is on board side chain eq allowing you to quickly adjust the compressor sensitivity at high and low frequencies.
The essence attack & release settings have been carefully selected for a varied dynamic palette and the intelligent auto modes allow for really good "set and forget" operation. The soft knee opto action is particuly excellent for tracking vocals and bass guitar.
GAIN - sets the output gain from 0dB to +15dB.
DRIVE - sets the amount of compression applied to the signal, clockwise rotation means more compression.
ATTACK - 4 position switch with attack time settings of 1mS, 15mS, 70mS and our excellent Auto mode.
RELEASE - 6 position switch with recovery time settings of 100mS, 200mS, 400mS, 800mS, 1600mS and the intelligent Auto mode..
RATIO - 4 position switch sets the depth of compression from light to heavy, 2:1, 5:1, 10:1, 20:1 all with the soft knee action.
METER - can be switched to read input level, output level and gain reduction. A jumper on the pcb is used to set the peak level reference from +4dBu or +14dBu.
BYPASS - toggle switch used to hard wire bypass the essence.
S/C MON - allows you to hear the side chain signal (the side chain eq) and the side chain insert return signal.
S/C HI EQ - applies 8dB at 10kHz of boost or cut to the side chain signal and therefore to the compression.
S/C LO EQ - applies 8dB at 100Hz of boost or cut to the side chain signal and therefore to the compression.
LINK - using the 500 frame link system, two essences can be linked for stereo operation.
S/C INS - this switch engages the side chain insert point which are the input/output connectors associated witht the second slot the essence uses.
Frequency Response with no gain reduction: 14Hz to 107kHz, +/- 1.5dB
Maximum Input Level: +25dBu
Maximum Output Level: +27dBu
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
Sidechain Max Input/Output Levels: +22dBu
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.