User`s manual

the various ratio settings when doing approximately 10 dB of gain reduction, however at
less amounts of gain reduction the lower ratio settings will start compression sooner than
higher ratios.
3.5 Attack and Release Controls
The Attack and Release controls determine how quickly the dynamic range is adjusted by
the compression. The effect of these controls can be heard as well as observed in the
meter action. The Retro 176 has extended adjustment of the attack and release
characteristics.
Slow Attack lets more impact through. Fast Attack holds down peaks and sounds more
stressed.
The Release control set faster adds energy and density. Slower settings give gentler
control and retain more of the original source dynamics.
The Attack knob has a pull switch that disables the Retro 176 program-controlled time
constant. The original UA 175B and 176 have a single time constant. By pulling the
Attack knob OUT you can have that mode. The program-controlled time-constant (with
the knob IN) makes the Retro 176 gain reduction more natural, better controlling
dynamics with less distortion.
3.6 Sidechain High Pass Filter
The Sidechain HPF is a very effective tool to eliminate pumping on low frequency
material. It allows the compression to work more effectively controlling dynamics in the
midrange frequencies. Bass frequencies will pass through with little or no control, so it
really depends on your application. The Sidechain HPF is ideal for vocals. It is disabled
by a switch at the minimum setting.
3.7 Asymmetry Switch
Many voices and instruments are highly asymmetrical waveforms. The Asymmetry
Switch selects whether the detector is full-wave, detecting both positive and negative
sides of the waveform or half-wave, which detects only one side.
With the Asymmetry switch set to + or −, you generally hear the compression open up.
You will notice the most effect on signals that look spiky on your editor screen.
Generally the spikes are facing one direction, up or down. The other direction may be
smooth. The Asymmetry Switch determines which edge of the wave the compression
will ride on.