Mix-bus compression has been used in countless recordings. We all like a punchy mix that sounds cohesive, and mix-bus compressors have achieved this for many engineers. Applying this technique to your own mixes can be challenging. There are tons of compressors available, but they are not all created equally. Here are some popular choices for mix-bus applications.
The Manley Vari-Mu compressor is a shining example of what real tubes can do to your mix-bus. This compressor is known for bringing clarity and warmth to your mix, achieving this through the use of tubes to perform the gain reduction. This unit is found in many mastering studios throughout the world because of its ability to add the final glue that many mixes benefit from. Opposed to many other compressor styles, the ratios in the Vari-Mu go up slightly as the amount of gain reduction applied increases. When you use the unit to limit, the effect and color become much more apparent, but even when pushed, the signal will not suffer from artifacts as result of the effect. Its attack and release time are on the slower side in comparison to VCA or FET circuits so this may not be the tool for taming harsh transients, but the warmth, clarity, and glue are worth giving this compressor a try on your mix-bus.
Considered to be a classic bus compressor, the API 2500 is a VCA style compressor with many features that allow it to fit whatever kind of mix you may be working on. On top of the ability to stereo link from 50-100% and select “Old” feedback compression or “New” feed-forward compression, the 2500 has a unique “Thrust” feature used to shape the low end of your mix. There are three modes that allow for low end rolloff and high end boost to give the appropriate amount of punch to your mix through reduction of low end sensitivity. While VCA’s are often viewed as fairly transparent, the 2500 definitely adds a color that gives mixes the API sound. In terms of attack and release, the VCA design will allow for very quick times. Transient heavy material will sound punchy and be caught by the 2500 easily. This compressor is a classic for a reason and will tighten up your mix with some API color as an added bonus.
All tube, heavy, and a little pricey…just what we all want to hear right? The thing with the Fairchild 670 is that this compressor is exactly what we all want to hear. This legendary unit has provided glue and punch for many mix and mastering engineers alike. It is known for its coloration due to its variable mu method of gain reduction. Similar to the Manley Variable Mu, the ratios that are set will actually increase as the amount of signal going into the circuit goes up. Like other tube compressors, the attack time on the 670 is not going to yield the fastest response to quick transients, often leaving it off of the list for hard transient taming, yet its ability to glue mixes together remains among the best. The 670 will add its famed color to your mix without squashing your dynamics, leaving it with a smooth sound full of tube character.
Originally a feature of the SSL 4000 console, the G Series Bus Compressor has gained popularity over its signature tone and glue that it imparts on mixes. Now free from the master section of the original console, this legendary VCA unit comes in a 1U rack unit, 500 series, and SSL X-Rack module. With so many forms, it is easy to integrate this unit into any studio. The G-Series is known for bus compression that makes a mix sound huge and punchy. Using its built in high pass filter, you can make sure that your low end isn’t triggering the gain reduction. Other features include an auto release and ratios from 1.5:1 all the way up to 10:1 making this a great bus compressor for all styles. The color of this compressor is part of the sound of the 4000 console, giving your mix an expensive analog character as well as the glue it has become a classic for.
Dangerous Music’s Compressor has gained popularity for transparency even when pushed to its limits. A VCA style compressor, this unit has sports fast attack and release times useful for transient laden material. It also shows off features such as Auto Attack/Release, True Stereo Dual Detector, and Smart Dynamics Dual Slope Detection (an auto limiter designed to prevent pumping due to peaks). With all of these unique features, the Dangerous Music Compressor makes sure your mix remains at the highest quality the entire time it is in use. Because of its transparency even at high ratios, this unit could provide the perfect glue for a mix you may not want to color as heavily. With all of these unique features and transparency in mind, this compressor would be a solid candidate for mix-bus application.
The CL 2A is another example of a classic mono compressor turned stereo. The CL 1B achieved its fame using a smooth, musical type of compression with an optical circuit and a tube output stage. The CL 2A gives us two channels of that same sound. It can be used an either a dual mono compressor, but the linkable channels make it a solid choice for the mix bus. Its optical design makes it a great choice for smoothing out the overall dynamic of a mix while retaining clarity. The tube output stage makes for a warm, punchy sounding mix. Transient heavy material may not suit this compressor well due to slower attack times than a VCA or FET, but if your mix needs warmth, punch, and overall dynamic control, the CL 2A is your ticket.
This compressor sports two different types of circuits to help shape your sound. Referred to as Twin Topology, the compressor can either engage a tube amplifier or defeat it to use a solid state amplifier. If your mix needs some color, the tube output stage can give the warmth tubes are known for, but if you are looking for a more transparent response, the solid state has you covered. Because of its optical style compression, the TCL-2 will does not beat the competition of VCA and FET circuits in attack speed. If your mix needs overall volume leveling or light compression, however, this unit is great. Because of its versatility in tone shaping and high quality design, your mix-bus can benefit from the TCL-2’s abilities.
Rupert Neve’s name holds a lot weight in the audio industry. From famous consoles and preamps such as the 1073, Neve has set standards for high quality audio equipment since beginning in 1961. The Portico II MBP (Master Buss Processor) continues this tradition of quality in this multi-feature VCA compressor. Sporting two channels of compression, limiting, and a stereo field editor, this unit looks to be a multifaceted tool for improving upon your sound. Both of the compressors can be set to operate in feed-forward or feedback modes for different types of compressor reaction. The feed forward mode aims to be transparent and the feedback mode gives a vintage vibe with a musical response. Because of the different modes and a VCA design, the Portico II can be used with many genres and varying levels of sharp transients. The single knob limiter features Neve’s Adaptive Release technology which can react to sharp transients and slow transients simultaneously, allowing for even more dynamic control with simple operation. The most unique feature of this unit is its Stereo Field Editor section. This circuit allows for control over the stereo width among certain frequency bands giving you more tone shaping control for your mix. With all of these features, the Portico II proves itself a worthy bus compressor full of versatility.
Described as clean and transparent, the Focusrite RED 3 can function as a dual mono or stereo linked compressor making it useful for individual track or bus operations. The VCA design allows for versatility of genre and transient levels and transparency when required. The RED 3 also features a single knob limiter to help control the sharpest of transients, auto release times, and key inputs selectable via a button on the front panel. The attack times of this compressor will allow for quick detection of fast transients if your mix contains many percussive or loud elements. On the mix bus, this compressor will treat your mixes with the glue you want without adding any character to them. If you’re looking for dynamic control with clean, versatile compression, the RED 3 could be the missing piece in your chain.
The UREI 1176 has long been considered a classic FET style compressor, providing punch and color for decades. Typical uses for the 1176 are drum compression or limiting because of its quick attack and release times. For mix-bus compression, the 1176 can be a great choice. The problem is that you’ll need two of them because of their mono design. Enter the 2-1176, a stereo version of the classic compressor. If your mix has many quick transients, the 2-1176’s attack and release can tame your mix while also giving color through the FET circuit. This may not be the piece of gear you choose to glue together mixes that are lighter on transients, but the punch and color of the 2-1176 can add life, clarity, and a cohesive sound to the right mix.