The dbx 166 Two Channel Gated Compressor/Limiter was a professional dynamics processor designed to give full control over level, noise, compression and peak limiting in a compact rackmount format. Built as a dual-channel unit, the dbx 166 Two Channel Gated Compressor/Limiter combined a noise gate, dbx OverEasy compression and PeakStop limiting on each channel, allowing it to handle everything from subtle dynamic control through to firm limiting and protection against excessive peaks. The dbx 166 Two Channel Gated Compressor/Limiter could be used as two independent mono processors or as a linked stereo processor, making it suitable for individual tracks, stereo submixes, complete stereo mixes, broadcast feeds and sound reinforcement systems.
At the input stage, the dbx 166 Two Channel Gated Compressor/Limiter provided electronically balanced differential audio inputs, with electronically balanced inputs that could also be used with unbalanced sources. Each channel included a gate section with a threshold control and selectable release rate. The gate operated as a below-threshold attenuator, reducing the signal by 40 dB when the input fell beneath the selected threshold.
This made the dbx 166 Two Channel Gated Compressor/Limiter useful for reducing unwanted background noise between wanted sounds, controlling vocal microphone noise, reducing spill between microphones and tightening up drum sounds. The fast release setting was particularly suited to percussion, while the slow release setting was intended for general-purpose noise gating on vocals and acoustic instruments.
The compressor section of the dbx 166 Two Channel Gated Compressor/Limiter used dbx OverEasy compression, designed to avoid the abrupt, unnatural character often associated with high-ratio compression. Rather than switching suddenly into compression at the threshold point, OverEasy gradually changed the ratio as the signal rose above the threshold, moving from 1:1 towards the ratio set on the front panel.
This allowed the dbx 166 Two Channel Gated Compressor/Limiter to provide moderate compression around the threshold while still offering stronger limiting behaviour for signals well above it. The ratio control covered everything from gentle level smoothing to full limiting, with higher ratios such as 6:1, 10:1 and infinity:1 suitable for controlling peaks and preventing output levels from exceeding the desired range.
The dbx 166 Two Channel Gated Compressor/Limiter also included gain reduction LED metering, showing the amount of attenuation being applied by the gate, compressor or both. This made it possible to judge the amount of processing visually while setting the unit by ear. The output gain control allowed the user to restore or reduce level after compression, with a range of -20 dB to +20 dB. Since the PeakStop circuit followed the other processing stages, it remained the final level control in the signal path and could still limit excessive peaks even when output gain was increased.
PeakStop was one of the key features of the dbx 166 Two Channel Gated Compressor/Limiter. It was designed as an adjustable peak limiter using a voltage-controlled clipping circuit that rounded off peaks rather than cutting them sharply. This allowed the dbx 166 Two Channel Gated Compressor/Limiter to reduce short-term overloads, large transients and excessive output peaks with less harshness than conventional hard clipping.
PeakStop could be used to protect downstream equipment, prevent broadcast overmodulation, reduce the chance of tape saturation and protect loudspeaker systems from damaging level excursions. The PeakStop LED indicated when peaks were being reduced, and the manual recommended setting the PeakStop level slightly below the required ceiling when an absolute maximum output level was needed.
The sidechain input on each channel gave the dbx 166 Two Channel Gated Compressor/Limiter more advanced control options. By inserting an external processor into the sidechain, the compression or gating response could be made frequency-sensitive. This allowed applications such as de-essing, frequency-selective compression, suppressing an over-loud kick drum in a mix, preventing high-frequency tape saturation from cymbal crashes, protecting specific loudspeaker drivers, keyed gating and selective drum gating. The Sidechain Monitor switch allowed the user to listen directly to the sidechain signal during setup, making it easier to adjust the external processing before returning to normal operation.
In stereo operation, the dbx 166 Two Channel Gated Compressor/Limiter used the Stereo Couple switch to link the two channels so that gain changes remained identical across left and right channels. This was important when compressing stereo material, overhead microphones, piano, vocal groups, classical stereo microphone pairs or a complete stereo mix, as it helped preserve stereo imaging stability. In this mode, Channel 1 controlled both channels, except for the Sidechain Monitor and Bypass controls, and the detection circuitry sensed the true RMS levels of the combined stereo signal.
The dbx 166 Two Channel Gated Compressor/Limiter was a practical and flexible dynamics processor for studio, broadcast and live sound use. Its combination of gating, OverEasy compression, PeakStop limiting, sidechain access, stereo linking and hardwire bypass made it suitable for a wide range of real-world tasks, from cleaning up noisy tracks and smoothing vocal levels to protecting speakers, controlling tape saturation and processing complete stereo mixes. No release date is stated in the provided material.
Features
- Dual-channel gated compressor/limiter.
- Each channel includes noise gate, OverEasy compressor and PeakStop limiter.
- Gate section provides threshold control and selectable fast or slow release.
- Gate attenuation is fixed at 40 dB.
- dbx OverEasy compression provides gradual transition into compression above the threshold.
- Ratio control allows gentle compression through to full limiting.
- Gain reduction LEDs show attenuation from the gate, compressor or both.
- PeakStop limiter controls maximum peak output level after the compression and output gain stages.
- Sidechain input allows external processing for frequency-sensitive compression or gating.
- Sidechain Monitor switch allows the sidechain signal to be monitored during setup.
- Output gain control provides -20 dB to +20 dB level adjustment.
- Hardwire bypass connects input to output, even without AC power.
- Stereo Couple mode links both channels for stereo dynamics processing.
- Electronically balanced differential inputs can also be used with unbalanced sources.
- Suitable for vocal level control, instrument levelling, tape saturation prevention, speaker protection, broadcast processing and stereo mix control.