TK Audio BC1-THD Stereo Bus Compressor

Delivering transparent compression and the magic glue that has been sought-after in countless studios for decades, the BC1-THD from TK Audio is a stereo bus compressor designed to offer stronger mixes, sonic clarity, and even open up new avenues in mixing and mastering applications that might not be possible on lesser devices. The blend control makes it incredibly easy to engage parallel compression through simple adjustment of the dry and compressed signals, and the switchable side-chain filter can be paired with three high-pass filter frequencies at 80, 150, and 220 Hz to filter out low-frequency audio material either internally or from external signals.

The innovative THD function adds more harmonics to your signal for more color, while Grab mode selects a harder threshold knee on all four of the available ratio settings. The BC1-THD sports 10 attack and six release settings, including an autorelease that varies depending on the duration of the signal peak for a release behavior much like the classic British bus compressors used since the '80s. All controls are stepped for perfect recall.

Threshold and Makeup Gain

The BC1-THD provides a -20 to +20 dB threshold range in 41 steps. The threshold adjusts the level above where the signal is reduced. A lower threshold means a larger portion of the signal will be treated. You also get 0 to +20 dB of gain in 41 steps to balance the compressed signal level against the input signal level.

External Sidechain

By using the external side-chain, another signal can control the behavior of the compressor, a feature most commonly used by DJs for ducking or lowering the music volume automatically when speaking. It's also effectively used for ducking the bass track or background whenever the kick drum hits by sending the kick track to the external side-chain input.

Ratios

The BC1-THD features selectable ratios including 1.5:1, 2:1, 4:1, and 10:1. The ratio determines the input/output ratio for signals above the threshold. For example, a 4:1 ratio means that a signal overshooting the threshold by 4 dB will leave the compressor 1 dB above the threshold.

At the 1.5:1 and 2:1 setting, a relatively subtle soft-knee compression is applied. At 4:1, the compression becomes more obvious, and at 10:1, the BC1-THD is basically a peak limiter.