Room setup and subwoofer integration using REW - your opinion needed!

[MediumRare]

Hey folks, I'm hoping to get your help on finishing the setup of my room. Here's what I’m working with:
- McIntosh MA6900: 200-400 WPC integrated amp with 5 EQ knobs (low Q @ 30, 150, 500, 1500, 10k Hz)
- B&W 804 Nautilus speakers (-6 dB @ 42Hz)
- 2 Rythmik F12 subs

Before setting up anything I tried a lot of REW Room Sim options, which essentially did work out IRL and have ended up with the layout below. (The room is approximately 24'10" x 17'1", with an 8'8" ceiling and carpeted floor. It's not exactly accurate, as the left wall has two different depth sections, with a hallway opening in the center; what is shown is as if it's all one dimension). The cones of the mains are 20" from the front wall, any more and they risk being knocked over. They are 7'10" apart and there's a flatscreen TV in-between, but above the tweeter level. The mains face straight ahead, so in a way that isn't so different from 60 degrees but then with each being toed-in 7.5 degrees. There is a large coffee table in front of the PLP and I did the measurements with a heavy blanket over it.

I had wanted the mains wider to get a 60 degree equilateral triangle, but I needed to bring the mains closer together and push the PLP back as far as possible to optimize the room modes, especially LF and the 128 Hz suckout. I played quite a bit with the subs' individual phase/delay and crossovers (and on one sub I used the onboard PEQ) to optimize the FR graph and minimize distortion. Sub cross setting at 50 Hz. This is absolutely the best I could do on my own to the fix the suckout at 128 Hz; part of the solution is using +4 dB EQ on my 150 Hz knob. This is the result:

To be honest, listening to music it sounds pretty good to me. The soundstage is massive, with pinpoint accuracy horizontally and vertically, and the bass is very tight and big, to my ear - I tried various demo tracks to check all that. (Unfortunately I've lost any hearing above 14k Hz and, when I'm playing loud (like 100 dB) I have some LF resonances from furniture I can't get rid of.)

BUT: then I tried some bass test tones and found there are loads of audible phase and SPL differences in the LF which make me second-guess myself. So.... here we are. What do you think I can/should do?

REW mdat file:

https://www.avnirvana.com/attachments/mar-21-2025-mdat.82517/

Thanks!

 

[ernestcarl]

Both your subs and mains have a big dip around 130 Hz likely because they share similar positioning (distance from the front wall).

I have a single Rythmik F12 sub here, and while the sub is pushed very close to the front wall, my mains are pulled-in well towards the listener position ... a peak/dip in one LF response source is equalized or balanced by the another LF source.

I played a bit around with REW's 'alignment tool' moving the time offset and changing the polarity of your sub measurement's IR but couldn't really improve the summed response (mains+subs) more than what you already have done there.

My sub is set to some very minimal settings e.g. PEQ not engaged, no rumble filter, phase adjustment etc. since I do most any signal processing in my own computer.

The room you're in does not appear to have much acoustic bass dampening compared to the somewhat "dryer room" (largely built-in structurally in the basement of the house) I have.

Magnitude, phase, ETC, step response:

*Subtracted 55.7 ms from your sub IR measurement to match the actual alignment of your subs+mains.

Much of the excess phase seen in your IRs might be almost certainly is from the room itself rather than any significant difference in the DSP used.

 

[Keith_W]

If you apply ERB smoothing, that suckout at 130Hz disappears.

You can certainly spend brain cells and time worrying about that 130Hz suckout to make the measurement look nicer. But I doubt if you would hear much of a difference.

If, as you say, it sounds good to you then there is nothing you need to do. That subwoofer is much louder than I would like (about 10dB over 1kHz reference level) so I would turn it down by about 6-7dB.