Audiolense XO + HAF Room Shaper?

[Dali_20]

I would like to kindly ask @juicehifi for a technical comment on the following:
A Home Audio Fidelity plugin called Room Shaper has been available for a few years (product link with brief technical description).
From what I understand, it selectively intervenes on late acoustic events up to 600Hz frequency, with a psychoacoustic option to also intervene on treble. It seems that in the latest version it also intervenes on the onset part of the impulse, not only on decay.
But it is not about filtering or emitting cancellation waves, rather about change timing and duration of certain frequencies (here there is a more technical explanation by its creator).
This seems can be considered complementary to the operation of FIR-based DRCs, at least that's what I understand from an article by Mitch Barnett, plus one of his post on ASR explaining why it's so special.
Now, since I'm not that competent, I can't understand why the AL TTD correction cannot achieve the same result since it also works in the time domain to correct excess phase (of room).
Is it correct to consider the two products complementary or can AL TTD achieve the same result with proper FDW?

 

[juicehifi]

I haven't tried it, Dali_20, so I wouldn't know what it does to the sonic experience.

This look like some kind of impulse response manipulation that could be done either with FIR or possibly IIR filters. The FIR version would be a dirac pulse followed by 300 ms silence and with the inverse of the decay from 300 ms and out., for instance. An IIR version could possibly be set up to attenuate the tail over an infinite duration. There could be more to it than this, but I fully expect there to be "normal" DSP under the surface. Needless to say, such a correction will influence the direct sound and anything between also. Everything you do with the signal will influence all parts of the resulting impulse response..


I can't tell how it will sound in company with Audiolense. I am personally much more conserned with the artifacts that are stronger than -30 dB than those who are weaker. But yes you're right in assuming that a strong TTD correction also will attenuate the tail.

 

[Dali_20]

I am noticing that there is a lot of late energy in the infrasound of my system, that Room Shaper seems to reduce also.
Is there any way to apply 20Hz high-pass filter to Audiolense?
Is it enough to draw a target with a steep slope before this frequency?

 

[juicehifi]

You can do it with the target.

 

[Dali_20]

I asked because AL manual says this:

Note that all targets drawn level out towards 0 Hz and the top frequency. This is recommended, since steep slopes at the extremes sometimes will lead to less precision in the filter generation

I was thinking that alternatively I can set the hpf in the crossover, but for some reason when I type the value in its speaker configuration field it is not taken.