Is it possible to automatically correct the phase using REW arithmetics?

[Digital_Thor]

Can't find the your speakers.... is it the small bookshelf or the floorstander?
The dips could be a lack of overlap between subs and mains. Try to make the mains play 30Hz lower than where you cross your subs. And if you need HP on the mains, let it be a very low order one. Then cross your subwoofers sharply - I cross mine with 96db.
I use 4 subs, have 4 different crossovers - one for each sub - and have no where near you level of dips - even with IIR alone.
Could the other dip be you mains position? Distance to rear wall?

 

[AudioBoy]

Your sub volume maybe too much compared to the speakers.

This is true. I did this on purpose. I decided to extend the low frequencies as much as possible so that I could correct them using the equalizer, avoiding boosting the dip points.
So only the peaks should be suppressed to the level of troughs.

I also noticed something strange about the measurements of my subwoofer and speaker. The louder my subwoofer is, the less distortion I get from the speaker connected to it.

By the way, using the subwoofer this way is not a problem because I use it at a preset level of 94 dB, and there are two other gain switch positions that are much louder (>100 dB). So I have some reserve. But I would, of course, prefer to use the gain level in accordance with the speaker level, but, alas, in this case I will never be able to pull out the dips at a suitable level. This trick more or less works for me, but the bass is not my headache right now. But I still appreciate your help.

At high frequencies there is a mess due to the poor location of the speakers (close to the walls). I need to find smaller speakers (I have new Polk Audio R 200 that are lying around) or try to somehow hang them at a greater distance from the table and point them clearly at the listening position. I think maybe I can put them on their side...

 

[AudioBoy]

Can't find the your speakers.... is it the small bookshelf or the floorstander?

Dynaudio Contour 20i + Nuemann KH750 on each side.

 

[Digital_Thor]

Dynaudio Contour 20i + Nuemann KH750 on each side.

Ah... now I see... the bookshelf it is.
Maybe if you set them up like this:
https://www.audiosciencereview.com/...71d1-b10d-4fff-91d4-6c696e89b1b6-jpeg.119545/

 

[AudioBoy]

Then cross your subwoofers sharply - I cross mine with 96db

The problem is that Neumann doesn't have the software or hardware to set it up. There was software for Apple devices that they decided to bury after the latest subwoofer firmware update. It was also not ideal, but at least something that could be used to manually configure the subwoofer over the network.

They also have the MA-1 software, which is far from perfect and doesn't suit my needs because this is a fully automated system that does not allow you to configure subs in stereo mode without various tricks. So I'm forced to use the standard 80Hz crossover frequency.

I have already fixed the subs phase. At the beginning there was some kind of unpleasant dip that I could correct more or less.

 

[Digital_Thor]

Oh.. I see.
Always loved the freedom to do as I please with most software, and can surely understand your frustration in this regard
Certain software has a certain philosophy that they hold very tight. It's almost like they pre-made a setup and didn't even think to leave much play for creativity.
I thought the Neumann subwoofers had their own little DSP build in, to do as you please?

 

[AudioBoy]

Always loved the freedom to do as I please with most software, and can surely understand your frustration in this regard
Certain software has a certain philosophy that they hold very tight. It's almost like they pre-made a setup and didn't even think to leave much play for creativity.
I thought the Neumann subwoofers had their own little DSP build in, to do as you please?

That's why I planned to write my own application (in Python or C++) to work with the subwoofer's DSP. Neumann uses the Sennheiser audio control protocol. But first I want to fix the HF range as much as possible.