With variable wet/dry mix and output gain, you can engage in parallel compression internally, without the need for external audio gear, and each band sports the features one expects of a studio-grade compressor, including threshold, gain, mute, bypass, and switched attack and release, including program dependent release settings. You can use the Big and Air switches to activate low- and high-frequency boosts respectively, and the two analog VU meters make it easy to keep an eye on your signal levels, including a +10 dB meter rescale mode, and a switchable Peak mode to see fast transients. The 1973 includes an AC power cord, and an internal, toroidal power supply with user-selectable voltage switching for global compatibility.
In a mastering situation, having independent control over each band can resolve a problem mix, pulling out individual instruments, brightening the brilliance/air, or making the bottom end of a mix sound huge while simultaneously avoiding pumping or breathing artifacts. It can also increase the available headroom.
The front panel consists of three nearly identical compressor bands, flowing left to right, with the Variable Crossover Frequency knobs separating them. To the right are the large, illuminated VU Meters, with variable Output controls and the bypass switch underneath.
One criticism of multiband compression is that it is possible to take the effect too far and ruin a mix, but this is easily prevented with the 1973 through the use of the Mix control, allowing you mix in less of the wet signal and more dry. By the same token, the mix control can add more compression simply by adding more of the wet signal. It's that simple.