IIR Filter Design
The IIR tab & Branded EQ Modes | IIR Brand Conversion | Auto IIRs
FIR Designer isn’t just for FIR filters … it is also an advanced IIR filter designer & (brand) emulator, as well as an IIR automation & conversion tool!
The IIR features & functionality built into FIR Designer (& FIR Designer M) are invaluable when equalising individual loudspeakers or entire systems, creating combination IIR+FIR loudspeaker presets &/or working with different audio processor brands.
The IIR Filters tab & Branded EQ Filter Modes
The IIR Filters tab is a key part of the DSP design workflow in ALL our filter tools, enabling the selection & emulation of any IIR based filtering that will be used in the processor.
Available built-in filter types include parametric, low and high shelf, notch, band-pass, all-pass, and low-pass & high-pass Bessel, Butterworth, 2nd order variable Q, Chebyshev I & II, Elliptic, Linkwitz/Riley & Neville Thiele notched crossovers.
Since common parameters in many standard IIR filters produce different results on various amplifier/processor brands, a ‘Filter mode’ option on the IIR tab allows a specific branded mode to be used so that the IIR filter behaviour matches the chosen processor.
See the latest list of brands with a built-in EQ mode and get information about control software and file formats and learn how to create EQ for processors without a built-in IIR mode.
(Branded filter modes are available in FIR Creator EX, FIR Designer & FIR Designer M.)
IIR Conversion Between Audio Brands
Accessed directly from the IIR Filters tab, the IIR Reference Editor facilitates the swift creation of presets or tunings with identical IIR performance across different brands.
Set any brand as the Reference then – in a single click – convert existing IIR filter settings to another brand, with an exact match.
(Where two products don’t have equivalent filter types, additional filters can be added & adjustments performed manually to ensure an exact match.)
When original IIR settings are unknown, a measurement (in a supported file format) of an IIR response from any processor can be loaded as a Target, and filters in the IIR Filters tab set to match it. Learn more about how to match EQ between brands without knowing original EQ settings.
(The Reference Editor & brand conversion is available in FIR Designer & FIR Designer M only)
Auto IIR
Dramatically speed up the EQ process by automatically selecting & setting parametric filters to match a response to a target response.
The Auto IIR function is accessed from the IIR Filters tab & works with the non-branded Generic mode and any of the branded IIR filter modes.
Key parameters to set for auto IIR generation include desired input smoothing, frequency range & the number of filters (to match the available number on your processor). Automatically generated IIRs can be added to the IIR tab with a single click, where they can be turned on/off and adjusted just like any other IIR filter.
All IIR filters (whether manually or automatically created) can be exported directly from the IIR Filters tab, or as part of a combined FIR+IIR preset from the Export tab.
(AutoIIR is available in FIR Designer & FIR Designer M only)
No IIR Mode for the Brand You Need?
FIR Designer can also be used to design accurate EQ for processors that don’t have a dedicated branded IIR mode. Any of the IIR modes can be used as a starting point, with filter settings manually adjusted to match the destination processor.
Learn how to design IIR-based EQ for audio brands without a dedicated IIR mode in FIR Designer.
Providers of DSP-enabled audio devices (e.g. processors, amps, & related control software) are invited to provide Eclipse Audio with the necessary information for inclusion of a branded IIR mode in our software tools.
Learn More
Providers of DSP-enabled audio devices (e.g. processors, amps, & related control software) are invited to provide Eclipse Audio with the necessary information for inclusion of a branded IIR mode in our software tools.
IIR Filter Export
IIR filter parameters and raw coefficients, created within the IIR Filters tab, IIR Reference Editor and the Auto IIR window, can be exported to text files and the parameters copied to the desired control software. (Some specific IIR filter export formats are also available, such as CSV or QSC Q-SYS and WAY EQ for RAM Audio & RMS Acoustics.)
The export process is automated (via Direct-To-Processor functionality) for Powersoft, Marani, Lab Gruppen & Lake Processing. (Note: the Lake FIR 3-way & XP modules and the Lab Gruppen IPX series amplifiers, can accept raw IIR filter coefficients generated by any of the branded IIR modes.)
The IIR Filters tab is part of the workflow for all our DSP design tools. The IIR Reference Editor and Auto IIR features are available in FIR Designer M & FIR Designer, and accessible only with software licensees. (They are not available in free demo versions of the software.)
IIR Filter Design FAQs
Can FIR Designer create IIR filters automatically?
Yes. The AutoIIR function in FIR Designer automatically sets parametric filters to match your preferred target response. You’ll first need to specify some parameters including input smoothing level, frequency and a total number of filters (as per your processor’s limits). Once the IIRs are automatically generated, add them to the IIR tab with a single click, then its possible to adjust their settings and use them in your EQ designs the same as any manually-created IIRs.
This video demonstrates how to use AutoIIR for automatic filter creation in FIR Designer.
Can I use IIR filters and FIR filters together in the same DSP design?
Yes. FIR Designer can combine both IIR and FIR filtering within the same DSP design, and can export filters along with specified Gain, Polarity & Delay settings as a complete preset for EQing a single loudspeaker or complete system.
FIRs and IIRs have different capabilities and the optimal EQ designs often include both filter types (learn more about FIRs and what they do differently to IIRs).
Can I export IIR filters from FIR Designer for use in my audio processor?
Yes. FIR Designer isn’t limited to FIR filter design & export alone. IIR filter sets created in the IIR Filters tab in FIR Designer can be exported in different file formats for use in any processor or amplifier with user-accessible EQ settings. Most processor brands require the data be manually entered into their control software, although some support direct file upload.
IIR filters can be exported individually or as part of a complete loudspeaker preset, along with FIRs, gain, polarity & delay. Keep in mind that while nearly all processors accept IIR settings, only a limited amount accept FIRs. Find out which brands support FIR filters as well as IIR filters.
