The Black Box Analog Design HG-2 is a line level, stereo unit designed to add saturation, harmonics, natural compression, increased RMS and enhancement during mixing and mastering.
The HG-2 uses Cinemag input transformers to feed two paths: The main signal path travels through a 6U8A Pentode tube stage that then drives into the Triode stage that follows, resulting in everything from subtle harmonics to full on saturation.
Also fed from the input transformer is a parallel signal path that utilizes a set of 12AX7 tubes, voiced specifically for harmonics and saturation. This parallel saturation circuit is outfitted with a 3 way "Freq. Select" switch that allows the user to choose the frequency content of the signal feeding the circuit. The "low position saturates just the low mids and sub frequencies, the "flat" position saturates full bandwidth and the "high" position saturates only the high mids and high frequencies. The result is the ability to add top end to dull tracks, enhance low end or enhance and add energy to the entire signal. The "harmonics" knob allows the user to control how much of the processed, parallel signal is fed into the main signal before hitting the Pentode stage. Finally, both stages reach the passive output attenuation before a pair of Cinemag output transformers.
In addition to the saturation stages, an "air" switch adds a subtle top end lift and the "alt" tube button switches between two different 12AX7 tubes in the parallel circuit. Switching between tubes allows the user to swap tubes for different types of saturation and switch back and forth instantly.
The meter select chooses whether the meter is fed from the input or output, and the "bypass" switch is a true bypass that shorts the input directly to the output with no additional circuitry in line.