DBC: "Diode Bridge Compressor"


About

The DBC is my take on the diode bridge compressor topology. It is a stereo unit with one set of controls for both channels. It is a little bit of a frankenstein—the front end is similar to the classic Neve designs, the sidechain is similar to some fet compressor designs, and the gain makeup is done with high-quality modern opamps. The result is a highly flexible bus compressor that is squishy in all the right places. Like my "Super Passive Equalizer" design, the inputs and outputs are transformer balanced, with true relay bypass.


Video Demonstration


How It Works

The Diode Bridge Compressor features a typical set of bus compressor controls, with ranges of control that emphasize flexibility.

The gain reduction cell is similar to classic Neve designs - a step-down transformer followed by a diode bridge.

The makeup amplifier consists of a high-gain fully differential amplifier composed of modern op-amps. This feeds an output fader and the line output amplifier, which drives the output transformer.


Description of Controls


All controls affect both channels

Output - Output fader. -∞db at full counterclockwise

Threshold - Compressor threshold control. Clockwise = No compression, Counterclockwise = Most compression

Ratio - Intensity of gain reduction when compressing. Clockwise = Higher ratio, Counterclockwise = lower ratio

Attack - Attack time

Release - Release time

Speed - 6-Position switch. Affects the overall range of both the Attack and Release controls.

Hold - Pushing this switch "holds" the gain reduction where it stands. Useful for slow speeds.

Comp In - True bypass switch. Out = Bypass, In = Compressor In

Meter - An arbitrarily-scaled analog panel meter. Exact model varies. More meter movement = more compression.