apQualizr2 - Linear Phase Dynamics - Expected Behaviour?

[Tektra]

This is not necessarily a bug, but I wanted to ask about the behaviour of the dynamics module in linear phase mode. It seems that the detector gets triggered early compared to the other phase modes. For example, setting up the dynamics module to use transient detection and connecting it to the output module to apply a short boost to the entire signal (no filters) works great with mixed, analog, and minimal phase modes; however, when switching to the linear phase mode, the volume envelope seems to be triggered early and the volume boost is applied too late relative to the input signal (thus transients aren't boosted as expected). From what I can discern, this same delay also occurs when using peak and RMS detection modes.

Is this an expected behaviour, or perhaps a consequence of linear phase implementation? Am I totally missing something? This stuff is way above my head, so there's a good chance that I'm just doing something incorrectly or misunderstanding some aspect of this tool. Feel free to set me straight

Any thoughts appreciated!

[Pflugshaupt]

You are definitely not doing something incorrectly. The dynamics module is just a bad combination with the linear phase mode. The linear phase mode uses a lengthy fir filter which leads to a lot of delay that is usually compensated by the host. Additionally, in order not to overwhelm the cpu, the huge fir filter can only update a few times a second, which makes things like reacting to transients in the signal basically pointless. Using a fir-only solution was the only way to guarantee perfect linear phase. In most cases and especially when using dynamic modulation, the mixed mode is much better suited, where a combination or IIR and short FIR filters lead to almost linear phase for higher frequencies. This also leads to much less latency and can update much more quickly.

[Tektra]

Thanks very much for the thorough reply; that clears it up entirely for me.

Very happy apQ user here