In desperate need for help with dsp::IIR::Filter

Development
1

Hi,

No matter where I look, I find either outdated answers or examples that do not work when I copy them. I really need help to understand how to use an IIR::Filter and how to update its coefficients.

I am trying to make a three bands EQ with simple low shelf and high shelf filters, therefore VariableStateFilter isn’t usable because it lacks said shelf filters. The idea is to simply set the gain and frequency of the low and high bands, it should be very straightforward.

I need a clear example of how to do this in the simplest way. I see ProcessorDuplicator being used in most tutorials yet some features from it seem to have disappeared over time, leaving said tutorials obsolete. I need a 2026 update on the matter.

I thank you in advance, JUCE community.

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Personally I wouldn’t bother with the JUCE built-in filters. Here’s a simple implementation of Simper’s SVF that has shelving filters: Cytomic SVF implementation in C++ · GitHub

The important thing about using this class is that you need to make one instance for the left channel and another for the right channel.

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Thanks a lot, this looks really clean and works per sample just as I needed!

Have a nice day :slight_smile: