A certain passive EQ is now available as an Analog Code plugin -- Sound Performance Lab (SPL) has released its Passeq plugin, the latest addition to the Analog Code series.

The new plugin features the same functionality as the original hardware, two display options (the standard two-channel interface and a space-saving single-channel version), a switchable M/S mode, and more.

The original Passeq hardware offered three separate frequency ranges for both boost and cut stages; there were 12 switchable frequencies per band, for a total of 36 boost and 36 cut frequencies. Like the original hardware, the Passeq plugin provides a dense network of passive filters in one single unit; each channel has 72 filters on three bands. The new Passeq plugin reproduces the original hardware exactly, offering all the same complex interactions between filters.

Furthermore, the Passeq plugin has two graphical user interfaces (GUI): "Passeq" and "Passeq Single." Aside from the standard dual-channel GUI, the single GUI represents a space saving alternative showing one Passeq channel. The single version can be applied to a stereo track -- you simply control both channels simultaneously with one knob.

The plugin's M/S mode offers an alternative to L/R encoded stereo signals. The M/S switch activates an M/S encoding of the L/R signals, allowing you to process the mid information with the left channel and the side information with the right channel. SPL notes that M/S encoding is only used for processing, whereas decoding into L/R format is done before the signal is output. Both encoding and decoding is lossless.

Its design is a bit different from what you might expect to see, but SPL promises that there is a reason for the circular arrangement of Passeq’s control elements.

The company writes, "Along with the fact that we simply like this design from an aesthetical view, this layout makes even more sense with respect to the idea of the passive EQ concept itself: In a passive design, filters for boosting and cutting a frequency range are physically separated from each other. Reflecting this fact, the elements left of the central output control perform level cuts, while controls to the right of this central regulator serve as signal boost controls. Cut and boost switches are positioned next to the appropriate frequency band selector and frequency bands are arranged from low to high from the standpoint of both physical and frequency range layout -- all in all a clear overall functional picture though without much in the way of boring routine."

SPL's Passeq Analog Code plugin is now available for approximately $199.66 (MSRP). For more information, visit the SPL Web site at spl.info.