Eventide Omnipressor 2830AU Compressor and Expander

It also introduced the notion of the side-chain and foretold techniques that today we take for granted like lookahead processing. One of its first customers was a young Brian May, lead guitarist of Queen. With the Omnipressor in his rig, his sound was never the same.

By making these envelopes louder than the peaks, the illusion that the sound is coming out backward is generated. Likewise, drum sounds consist of peaks roughly coincident with mechanical impact, followed by a decay envelope. In general. any material with wide dynamic range can be reversed, and by experimenting with forward and reversal playback, you can achieve an incredible array of effects.

• Dynamic Reversal: An input level of +10 dB results in an output of -10 dB, and vice versa.
• Gate: As the signal decreases below +10 dB, the device gain rapidly goes to minimum.
• Expansion: A 40 dB input range results in a 60 dB output range, increasing dynamic range.
• Control Centered: Input level equals output level.
• Limiting: Gain is unity until input is 0 dB. Above 0 dB, a 30 dB change in input produces a 6 dB output change.
• Infinite Compression: Output level remains unchanged regardless of input level.

• Line switch controls the relay-bypass function
• Input and Output level controls
• Mix control for wet/dry adjustment and parallel compression
• Side-chain enables or disabled side-chain audio path
• Input Threshold controls the operating point of the Omnipressor
• Bass cut for reducing low-end leakage into your signals
• Control Attack Time and Release Time
• Three-way switch for Meter Function: Input, Gain, or Output monitoring
• Main Function knob scrolls through basic modes of operation (compression, limiting, reversal, etc.)
• Atten Limit adjusts the limits of maximum attenuation, with a max reduction of 30 dB
• Gain Limit commands the maximum gain of the Omnipressor
• Link activates or deactivates the unit to unit linking function

Connect an Omnipressor and an Eventide Digital Delay Line, or similar delay device. Enable the side-chain input. What you have just fabricated is a compressor that can read the future, or, in more common parlance, one which has a negative attack time. 

Since identical circuitry with identical time constants is used to produce compression and expansion, perfect dynamic tracking is obtained. If compression and expansion ratios are set properly, the system should be transparent to the listener.