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This is similar to what I see, but when I restart the stereo coder it can be vice versa, or identical. For an honest comparison, set the pilot and RDS levels to 0, that removes most of the difference.
Enabling ABDP does have this effect, even if I set the bass frequencies to 0 and levels to 200%, and increasing "High priority" there makes it worse. So there's something left in ABDP - but without that I don't see this at all anymore with pilot and RDS at 0, or without composite clipping.
Yes i saw pilot interfere with this 3 tones, and yes i disabled both pilot and rds for test. More interesting is that there is much difference with different clipper level. so at 1dB clipper bar is kinda still ok.. at 5 bars is like on that picture.. but at 6 or more bars mids and some bass is comming back. And yes something in ADBP is doing this and its not any settings we have. Highs priority yes a bit, but it's not only that. Btw, "Leif's gap" off, is totaly vice-versa. Without composite things looks ok.
And to be clear, im testing all this because i am trying to find easiest way to make clipper as much as possible balanced over spectrum and response for given loudness level(s).
I found what's causing it, it's something that should not have such a big effect on the bass. I think (haven't tested yet) that these tones are kinda a worst-case situation for it, but aside from that, this behavior is affecting way higher frequencies than it needs to. It's a filter that protects the highs against IMD, and because I never expected it to do a lot it actually affects the bass upto around 220 Hz. Oddly, in earlier tests, this filter actually *increased* the amount of bass. But that was with music, not with test tones.
Edit: It's actually audible upto at least 200 Hz... but far less than at lower frequencies so I can probably at least use a different response curve.
Edit: I've done more tests. For low frequencies (< 100 Hz) the effect isn't strong enough, they typically need to be reduced by another 1-2 dB to make room for highs. For higher frequencies (120-250 Hz) the effect is too strong. Some more tweaking is needed, mainly to avoid reducing the bass more than needed if the level of the highs and bass is not very high - currently the algorithm starts to pull back when the input gets louder and that's actually the opposite of what it should do.
Ok, so before, there was a filter that was flat upto 200 Hz, then went down very steeply to 250 Hz. And that was the audio that was reduced when IMD occurred in the highs. I've now changed that to a smooth filter going down in a straight line from 0 to 200 Hz instead. I have made the effect stronger, so on this test tone recording the bass below 100 Hz tends to be reduced more than before, but with music it's typically less than before. I won't be able to fully test it until there's a release build (tomorrow). The filter can be reduced in strength if needed now, and you can switch between legacy and new mode. If it's always better without adjusting the preset, I might remove the legacy setting later.
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