FIR Designer Adds 'Auto IIR' For Accelerated EQ Design

Eclipse Audio's 'FIR Designer' software has been empowering audio professionals since 2016, allowing them to create custom loudspeaker processing with a comprehensive range of user-driven features.

The latest addition to FIR Designer -'Auto IIR'- accelerates the traditional IIR-filter-based equalization process for individual loudspeakers and systems. Version 4.2 introduces Auto IIR alongside an expanded selection of brand-specific IIR emulations.

"IIR filters are still more widely used than FIR filters for EQ," said Michael John, the lead developer at Eclipse Audio. "Moreover, when FIR filters are utilized, they are almost always combined with IIR-based EQ. That’s why IIR filter design is a critical aspect of our software and the area where we receive the most feature requests.

"Within FIR Designer, users can access dedicated IIR functionality to select and manually adjust any IIR-based filtering they want to use in the destination processor. With the recent expansion of this functionality to include Auto IIR, parametric filters can now be automatically chosen and configured to match a target response, significantly reducing the need for manual adjustments and expediting the equalization process. The automatically generated parametrics can be used independently or in combination with other IIR filter types, and can be manually fine-tuned just like any other filter. All IIR-based EQ settings can be exported individually or as part of a combined FIR+IIR preset.

The new Auto IIR function works with any of the built-in branded IIR filter modes, or the default 'Generic' mode. With v4.2, the list of branded modes has expanded to twelve, and now includes Biamp Tesira, Blaze Audio, BSS, Lake, Linea Research, Marani, Pascal Audio, Powersoft, QSC Q-SYS, RAM Audio, RMS Acoustics, and Symetrix. Utilizing a specific IIR mode guarantees precise matching of the IIR filter behavior with the selected processor, as it automatically adjusts for brand-specific differences in IIR filter interpretation. Moreover, engineers who work with multiple processor brands can easily convert filters from one brand to another with a single click.

"The customer feedback on Auto IIR & the branded IIR modes has been extremely positive," said John. "We've got some incredibly experienced customers who've been setting EQ manually for years and are now leaning heavily into the new Auto IIR tool to speed up their daily work."

Both FIR Designer & FIR Designer M version 4.2 include Auto IIR and the branded IIR modes. The software is available for download at The new functionality is not present in the free demo versions, so to see how it works, watch the video at