Introduction:

In the realm of recording studios, Capitol Studios has always been recognized as one of the greats. Renowned for its classic recordings and exceptional mastering services, Capitol boasts four dedicated mastering rooms where countless hits and classics have been perfected. With their access to top-of-the-line gear, it was only natural for Capitol to develop their own compressor. Thus, the CM5511 compressor was born. In this article, we’ll delve into the fascinating details of this in-house designed compressor and explore its digital counterpart, the Capitol Mastering Compressor plugin, created by Universal Audio.

Design and Development:

The CM5511 compressor was meticulously crafted by Capitol’s team, drawing inspiration from renowned compressors like the Fairchild 670 and Gates STA-Level. With input from mastering engineers, the compressor’s design was fine-tuned to meet the highest standards. Each of the four mastering rooms at Capitol received a custom-made unit, resulting in a consistent and unified mastering experience across all rooms. The CM5511 featured hand-picked components, including vintage Mullard tubes, John Hardy op-amps, and custom Cinemag transformers. Universal Audio had the privilege of accessing two of these exceptional compressors, allowing them to create a faithful plugin emulation.

Introducing the Capitol Mastering Compressor Plugin:

Universal Audio meticulously modeled the response and sound of the CM5511 compressors to bring the Capitol Mastering Compressor plugin to life. The beauty of this plugin lies in its compatibility—it doesn’t require any Universal Audio hardware and can seamlessly integrate with any audio interface and DAW. Let’s dive into the plugin’s features and enhancements.

Interface and Controls:

The Capitol Mastering Compressor plugin faithfully replicates the vintage hardware compressor’s aesthetics, featuring Bakelite knobs and VU meters (offering both dBFS and LUFS metering). While the controls are simple, they offer everything you need to achieve outstanding masters or enhance individual tracks. The stepped Input control allows precise signal level adjustment in increments of 2.5 db.

The sidechain (SC switch) filter of the Capitol Mastering Compressor plugin reduces the amount of bass signal before the compressor’s detector. This filter has three positions: Off, 1 (365 Hz), and 2 (700 Hz). Universal Audio modeled these filter options from two different CM5511 hardware units. By reducing compression and “pumping” on bass-heavy audio signals, the SC filter preserves the bass content of the audio signal.

The Threshold control sets the compression threshold. It operates in approximately 1 dB steps. Lowering the threshold by rotating it clockwise increases the compression. Signals that fall below the threshold are not compressed. It is important to note that a parallel high-ratio, fixed threshold limiter is applied to very loud signals to prevent excessive clipping in the output amplifier. However, there are no user controls for this portion of the circuit.

Attack and Release controls provide flexibility in shaping the compression’s timing. Available values are Slow, mS (Medium Slow), Med (Medium), mF (Medium Fast), and Fast.

The Ratio control governs the compression ratio. Let’s discuss this in more detail. A 2:1 ratio, for instance, reduces the signal above the threshold by two times, meaning that an input signal of 20 dB will be attenuated to 10 dB. Higher ratios will result in more compression. Users can click the + or – text labels to step through the ratio values. The original hardware does not include this control, but Universal Audio modeled the 3:1 and 4:1 ratios from two different CM5511 hardware units. Five ratio settings are available: 2:1, 3:1, 4:1, 6:1, and 10:1. It is essential to note that signals must exceed the THRESHOLD value before they are attenuated by the RATIO amount.

The OUTPUT control is responsible for compensating the gain added by the compressor. It has 24 positions and reduces the output level by approximately 0.5 dB per step, with modeled gain settings from the original hardware. However, this control only reduces gain and cannot increase output gain. For that, you should use the GAIN knob instead.

To set a compressor control to a specific value, simply click on the text label corresponding to that value. To reset a control to its default value, use an option-click (macOS) or alt-click (Windows). For more precise adjustments, shift-click the control.

Channel Flexibility:

The plugin offers the option to link or use channels separately, granting users the freedom to optimize their workflow. Each channel includes a side-chain filter, which reduces sensitivity to bass frequencies. Furthermore, the Capitol Mastering Compressor plugin supports both Mid/Side and stereo operation, enabling users to compress the middle signal separately (from the left and right) or process the entire left-right signal. The side-chain feature can be set to work in dual mono or linked mode, expanding the creative possibilities.

The CTRL LINK switch allows users to link or unlink channel controls. The switch is surrounded by an orange LED that illuminates when the controls are linked.

When switching from unlinked to linked controls, the LEFT/MID channel settings are applied to both channels. When the plugin is used on a mono track, the controls are always linked.

Additional Features:

The plugin includes several innovative features not found in the original hardware compressors. The Mix control enables parallel compression, allowing users to blend the dry and compressed signals to preserve attack and articulation while achieving the desired level of compression.

The Headroom control determines the compression depth, effectively managing the available dynamic range. Users can adjust the HEADROOM control from 4 to 28 dB in increments of 4 dB. The default setting is 16 dB. It is important to note that increasing the dB value will decrease headroom and increase compression, while decreasing the dB value will increase headroom and decrease compression.

The Mono Fold control is particularly intriguing—it enhances low frequencies, providing greater punch and impact while keeping the mid and high frequencies open. this essentially the stereo width of low bass frequencies. Users can adjust the Mono Fold frequency cutoff to their liking.

The Gain control acts as a makeup gain, allowing users to compensate for heavy compression or boost the output level for a louder sound. Gain provides ±12 dB of gain compensation, in 1 dB steps.

Lastly, the Saturator circuit adds harmonic content, offering brightness, richness, and even a touch of grit when pushed to the extremes.

The plug-in includes additional features not present in the original hardware, such as capturing the circuit design differences between two CM5511 units.

Enhance Your Instrument Groups with the Capitol Mastering Compressor:

Experience the warmth and tube-based magic of the Capitol Mastering Compressor beyond just the master bus. Add it to your drum bus, synths, background vocals, and more to achieve unparalleled dynamics control. This hit-proven hardware is a one-of-a-kind addition to any producer or engineer’s toolkit.

Presets and Versatility:

Universal Audio’s plugin management system provides efficient preset management. Users can filter presets by type, making it effortless to browse through options such as saturated masters, drum bus settings, or limiters. Alternatively, users can explore all presets without any filters and mark their favorites for quick access. The Capitol Mastering Compressor plugin excels in versatility, delivering exceptional results for various styles and applications, from smooth and polished masters to gritty and edgy productions.

Signal Flow:

The following diagram depicts how signals are processed in the compressor:

Conclusion:

The Capitol Mastering Compressor plugin from Universal Audio is a powerful and versatile tool for both mastering and individual track processing. Offering exceptional sound quality and faithful emulation of the legendary CM5511 compressors, this plugin is a valuable addition to any producer or engineer’s toolkit. With its intuitive interface, flexible controls, and innovative features, the Capitol Mastering Compressor plugin empowers users to create professional-sounding masters and take their productions to new heights.