SPL Stereo Q is a true stereo mastering equalizer, designed to achieve a perfect stereo equalization working only on one channel. In fact, this equalizer applies all the adjustments in both the channels, exactly in the same way; this feature is particularly useful in mastering, where the equalization adjustments, in 99% of the cases, have to be the same in left and right channel, to avoid stereo unbalances.
The equalizer is a solid state one, and has two shelves (“sub” for basses and “air” for highs) and three bells to control all the frequencies in low, mid and high spectrum. The three bells are fully parametric, while the shelves permit only to boost and cut at pre-selected frequencies. All pots are stepped, with the exception of gain pots that only have a center detent step. The equalizer is equipped with a bypass button that allows to completely bypass the circuit.
When used for audio mastering, this equalizer is very clean and powerful, and demonstrates to behave perfectly both for boosting and, overall, for cutting frequencies.
For boosting, sub and air shelves are very powerful to add deepness and brightness to the tracks.
Sub pot has to be used carefully, because it tends to make the sound too boomy if overused; however, with gentle boosting, it really can make the sound deeper, bringing out the kick and the bass. If used in conjunction with a bell cut at about 250 Hz, it permits to obtain the classical Pultec sound, huge and deep but also well defined.
Air pot can really make the sound brighter and pleasuring without increasing too much sibilance and harshness; if used carefully, it can really make the sound more defined and “professional”.
With the bells, you can boost the low-mid, between 150 and 250 Hz, for achieving a more old style sound; for adding more presence, you can boost gently at around 3-4 KHz, with a very wide Q at about 0.5.
However, this mastering equalizer excels overall when cutting. It is surgical and precise, and can really “cure” the sound if some excessive frequency is present somewhere.
Low bell can be used for example to cut ultra-low frequencies (down to 10 Hz) or mid-low frequencies that muddy the sound; on the other hand, mid or high bell can be used to surgically cut some harsh mid high frequencies, or to reduce the sibilance by cutting some specific high frequencies.
Because of the “true stereo” nature of this equalizer, every intervention is automatically replicated in both channels with great precision, and this really allows the mastering engineer to save time and concentrate better on the sound.
In a nutshell, SPL Stereo Q equalizer is a rare, great mastering equalizer, capable, overall, of precise cutting adjustments, but useful for gentle boosting too.