Not the “breaking existing settings” argument again please ! This is a serious BUG. When you ask the bandpass filter (which is again a parametric peak filter, and not a true bandpass filter, because their behaviour are not the same) to increase the gain of 12 dB, the gain is actually increased with a gain of 24 dB ! That means everybody who wants to use your class needs to know there is a problem, and that he has to add a workaround. You just can’t leave an audio effect doing something wrong just because you have done a bad implementation in the past, and because a lot of people are still using it ! I just don’t want to be forced to use a buggy class that I need to “hack” every time I need it. Or else, that means I must forget the idea to use your IIRFilter classes. And that you should at least tell in the documentation what your class is really doing.
Moreover, you can add some code in Tracktion to help the people that use your EQ to keep the same sound in their edits… For example, you should develop an EQ which does the right thing in Tracktion 4. And then, all the projects done with old versions of Tracktion will have their EQ gains converted before being saved in the T4 format.
Isn’t it better to try to improve the utilisation of JUCE in the future, instead of keeping some old bugs to help past projects to work indefinitely ? If you have followed this logic further, you had add some support in Tracktion 4 for computers with Windows XP and one core :mrgreen: