U73b

The U73b is a faithful emulation of a vintage German broadcast compressor/limiter which was often used for mastering between 1960 and 1980. It is an all-tube vary-mu compressor/limiter with adjustable release time option. The circuit has been exactly kept as it was originally designed and only added an input and output gain before and immediately after the compressor circuit to assist with proper adjustment of the compression.

GR Meter

Displays the amount of compression in dB. Please note that the Meter does not react with the Compression Amount parameter.

Calibration

The Calibration allows you to easily change the operational range of the compressor effect. By increasing its value, the module will require a hotter signal to compress and saturate, and inversely. We suggest to set this parameter to the headroom you use in your DAW recordings or headroom of your audio interface.

The default setting is -18 dB and it is loaded every time you load the module.

High Pass Filter

Adds a High-Pass Filter connected in the compressor/limiter circuit with around 100 Hz cut-off frequency and 6dB/octave slope.

Although this filter helps to create the unique sound of the U73b compressor, the bass roll-off might not be suitable for all instruments when mixing, or for all genres when U73b is used for mastering.

Compression Mode

The Comp. Mode knob switches between the Compressor and Limiter mode. The Compressor mode has a lower threshold setting and very gentle increasing ratio, in opposite, the Limiter mode provides a higher threshold setting with higher ratio but still with a smooth knee.

Release

The first three positions offer fixed release time, the other three positions marked with red labels provide adjustable release time dependent on program content.

Input/Output

Increasing the Input knob will result in more compression. To compensate the gain reduction introduced, use the Output knob.

Moving the Input or Output Knob while holding the Shift key will inversely link the two controls. It is very useful to use the module as a line driver when Comp. Amount is null.

Compression Amount

The Comp. Amount allows you to adjust the compression effect while benefiting the module’s saturation and color. Therefore, this is not a dry/wet parameter.