Buzz Audio DBC-20 Classic Diode Bridge Compressor

The DBC-20 is a new take on a vintage technique utilizing a gain reduction element of silicon diodes in a balanced bridge arrangement. The diode bridge is coupled via a “radio steel” laminated transformer of our own design. This element produces a desirable compression character that can best be described as tight, colourful and rich with harmonics. In the style of compressors from the 60’s, the DBC-20 incorporates a self-adjusting ratio whereby the compression ratio is progressively increased with deepening gain reduction. This feature allows for the control of very dynamic signals (such as vocals) in a seamless fashion. The DBC does sound very vintage but does not carry the vintage price tag!

The DBC-20 audio path uses our Class A discrete amplifier design in a balanced configuration from input to output. Operation of the compressor is easy with six switched attack and release times, a big knob for the amount of compression and an output gain control. The compressor can be switched to a Soft mode whereby dynamic peaks are partially retained. Another switch introduces a high pass filter to the side chain to lower compression sensitivity at low frequencies. These features make the DBC an ideal tool for manipulating drum sounds and samples. Check out the audio clips.

Each channel has a bypass switch and the side chain of the two channels can be linked for stereo operation. The large knobs with pointers allow for accurate resetting of the compressor and the fast response 15 LED bar graph meter accurately displays gain reduction.

Controls

Gain – variable pot that adds gain at the output to correct for lost level with 15dB range.
Compression – variable pot that sets the amount of compression.
Attack – rotary switch with 6 settings, FAST (less than 0.5mS)-5mS-10mS-15mS-25mS-50mS.
Release – rotary switch with 6 recovery time settings, 50mS-100mS-200mS-400mS-600mS and AUTO.
Hard/Soft – adds dynamics in soft mode for times when light compression is required.
Flat/Bass – reduces compression sensitivity at low frequencies.
Bypass/Engage – hard wire unit bypass to compare compressed and uncompressed signals.

There is also a handy power On/Off switch and the Link A/B which provides for stereo tracking to prevent image shift when used on the mix buss.

Specifications

Levels;
Maximum Input Level; +27dBu
Maximum Output Level; +27dBu

Noise; -80dBu (measured A Weighted with 10dB gain applied).

Gain; variable 0dB to +15dB

Frequency Response;
6Hz to 400kHz measured no gain reduction.

Harmonic Distortion;
At +10dBu input level, no gain reduction; 0.28% @ 100Hz, 0.25% @ 1kHz, 0.15% @ 10kHz
With 10dB gain reduction (Release set to 400mS); 1.5% @ 100Hz, 0.5% @ 1kHz, 0.5% @ 10kHz

Standard Operating Level; +4dBu

Size; 1 Unit 19″ rack mount, (482Wx44Hx250D).

Power requirements; 230V/115V selectable, IEC detachable power cable.

Specifications are typical of a production unit and are subject to change without notice.
0dBu reference = 0.775 volts RMS.