After releasing the hardware version of the passive equalizer Sound Performance Lab released a software version of this equalizer. And having checked out the hardware version a few times I found myself intrigued to try out the software version of the SPL Passeq.
In hardware passive EQing is about using electronic parts in a way that it has as little side effects as possible when using for EQing the sound. And for maintaining as much as possible of the original sound and change it with EQ is very useful. However it is also very subtle and hardly adds any colorization to the sound. This makes its use somewhat limited but you gain in result.
The passeq GUI is modeled just like the hardware and comes with a few more additions. Both versions have the 3 band LF/MF/HF cut and boost options at stepped frequency ranges. In addition the HF has an extra Q option bypass button and an output option.
The software version in addition has a M/S, link and memory buttons. Each EQ band has its own frequency regions with either a cut or boost option. But the 3 cut frequencies ranges don’t correspond to the 3 boost frequency regions. This is because just like choosing the frequencies for each band are susceptible to the choice for personal preference of the designers. They chose what they thought would be best applicable musically.
The HF boost Q option adds more flexibility to the HF boost stage which can be very useful for carefully tune the higher frequencies. At this stage I personally would also have liked a LF boost Q option as well. The output options are 0dB and lower meaning that there is no gain stage which is only logical since it is a passive EQ.
The link button is more like an ergonomically must if you’re using the passeq in stereo mode. You also can use the passeq single instance because it does both mono as well stereo processing. In M/S mode you most likely don’t use the link mode. And as a matter of fact I think the M/S mode is a more than welcome addition to the software version. Perhaps there are some people out there who added this M/S mode to their hardware units as well. Even though M/S processing is all the rage these days it simply adds more versatility.
Since I haven’t checked the hardware version together with the software version I only can make a comparison from memory. Both sound rather subtle and will perform better in an optimal environment. I do think the hardware version sounds more organic and can be pushed more to boost without distorting. For smoothing out a harsh high-end you can get some great results especially for dense mixes. For low-end processing its blending may end up making it too muddy though so you should watch out there. All in all its a great tool to add some character to your sound. Provided you are looking for subtle. As a mixing EQ you can use it of course but it lacks the some coloring compared to its competitors. As a mastering EQ I think you should add another EQ in your chain as well.
Price 149 Euro