Eventide 2830AU Omnipressor Dynamic Effects 

Processor Instruction Manual

The 50th anniversary Model 2830*Au Omnipressor® is a professional-quality dynamic modifier, combining the characteristics of a compressor, expander, noise gate, and limiter in one convenient package. Its dynamic reversal feature makes high-level input signals lower than corresponding low-level inputs. Musically, this reverses the attack-decay envelope of plucked strings, drums, and similar instruments and gives the effect of “talking backward” when applied to a voice signal. When a return to normalcy is desired, the LINE switch is used to bypass the Omnipressor.

The Omnipressor provides an unusually wide range of controls, useful in all pro- gram-controlled gain changes. The continuously variable Expansion/Compression control goes from an expansion range of 10 to 1 (gate) to a compression range of −10:1 (abrupt reversal); attenuation and gain limit controls adjust the gain control range from a full 60dB to as little as plus and minus 1dB; and variable time con- stant controls adjust attack/decay times over an approximate 1000 to 1 ratio. The unit’s bass-cut switch limits low-frequency response in the level detector.

The Omnipressor’s unique metering system employs a logarithmic amplifier to generate information on Input, Output, and Gain. Some of the unusual capabilities of the unit are illustrated on the graph below.

OMNIPRESSOR CAPABILITIES

A: DYNAMIC REVERSAL An input level of +10 results in an output of −10. An input level of −10 results in an output of +10.
B: GATE As the signal decreases below +10, the device gain rapidly goes to minimum.
C: EXPANSION A 40dB input range results in a 60dB output range.
D: CONTROL CENTERED Input level equals output level.
E: LIMITING Gain is unity until input is 0dB. Above 0dB. A 30dB change in input produces a 6dB output change. (Line is offset for clarity.)
F: INFINITE COMPRESSION Output level remains unchanged regardless of input level.