New REW user - subs/main alignment fun

[ParaWM]

Hi dear REW users,

Since about 5 years, I am a happy owner of a Denon X2200W, SVS PC-2000 sub and a Klipsch 5.1 set (RP-260F towers, RP-250C centre and R-112SW surrounds). Recently I finally got my second sub and bought a MiniDSP 2x4 HD with a UMIK-1 and fell down the rabbit hole. Installed REW, watched a ton of YouTube vids, read-up on this forum and AVSforum and spent the better part of last Sunday measuring and aligning everything to my best ability. I would like to share my results and approach so far here for some feedback. Off course, the more you learn about all of this, the better you realize that there is so much you don’t know yet. Some comments on next steps or pointers on errors would be much appreciated! The 2nd sub is a PB-2000 by the way, which is not identical to the PC-2000, but the internals should be the same.

I have the MiniDSP connected to the AVR on inlet 1 and the subs on outputs 1 &2. Rest of the speakers go through the AVR. After lots of reading my approach was: 1. Level match, 2. Align, 3. AVR Auto-Cal, 4. PEQ, and finally 5. Set the correct Cross-Overs and Sub Delay. That last one includes trying to align with the main towers. My AVR only has Audyssey XT (not XT32) and a single internal sub-out (despite two physical sub connections), hence the MiniDSP. All measurements were done at MLP with Multi XT off, DEQ off, Dynamic Volume off and XO’s set to max 250 in the AVR (when working on subs).

To start off, my room is far from optimal; not symmetrical in shape or furnitured and no room treatment. I also basically have no options to place speakers or subs anywhere else. To top it off my L-shaped couch is against the wall. Awesome starting point right

I gain matched the subs by putting both knobs on 50%, phase on 0 and LFE selected on the frequency knob. Connected the LFE input of each to the MiniDSP. Then I level matched them in MiniDSP software to 81 dB; had to put the closest sub at -3.8 dB. Then I took some measurements at the MLP of the individually (red/green) and combined as-is (blue).

Then I tried to align them by delaying and/or inverting my closest sub (PB-2000) in MiniDSP software. Found actually 3 different results that gave pretty good positive summation. I ranked them as follows: 1 - 11.75ms (red), 2 - 6.5ms (green) and 3 – inverted 1.25ms (orange). Blue was the unaligned as-is base case. Red seemed overall the most consistent. Ok, subs aligned then.

Then I ran Audyssey Multi XT and let it do its magic. The distances set by Audyssey were almost identical to the actual distances and the new “virtual” sub was set at 5.28 meter. After this I decreased my volume on the AVR from -15 to -20 (was getting late / neighbors) and remeasured the subs. Nothing much changed, all good. Did see a massive null at 160hz all of a sudden, but don’t think I should care since XO will be well below that anyway later on?

Then did some EQ in REW, applied some filters and put a HPF (BW 48dB//oct) so it would drop off around 16Hz (subs rated to 16hz). I think the result (red) was not too bad.

Then things started getting fussy, trying to align with my mains. I first took some measurements of my mains, centre and surrounds (I think) by putting their XO at 80 and keeping the rest at 250. Sweeps still 10 – 200 hz. Crossover at 80 since I thought that would be where I would likely have the XO and would like to see how they behave above that frequency individually. Or actually, as sets. So mains together, centre on its own and surrounds together. Outputs were pretty low (had to adjust Y-axis in this graph) and a hard drop for all below 110Hz. While XO was set at 80Hz. Then a big boost at 50Hz (room reflections?). Bit weird. Also pretty similar behavior from the Mains (orange), Center (green) and Surrounds (blue). Typing this out, I’m thinking that I probably did something pretty stupid here, but not sure what. But pretty hard and big gap between 60 – 110 Hz anyway.

So the aligned subs (new virtual sub) and Mains individually measured after Audyssey in one graph

Then I started to look at them together with XO at 80, and aligning the subs with the mains by changing the distance of the single virtual sub in the AVR until I had some positive summation. It appeared I was rather looking for the least negative summation, since I never got above the subs by themselves. I found the best combined output at a AVR sub distance of 5.9m. But the big gap from the mains between 60 – 110Hz maintained. Combined output was much lower there. I then started increased the mains XO and saw that gap reduce each step higher on the XO, which makes sense off course. I deleted the XO 80 result, but this shows the XO at 100, 110 and 120. I am showing through pure MS Paint skills where the 80 result was roughly.

I ended up, for now, with the XO at 110, but not too happy yet. Combined subs + mains 5 dB drop at 130Hz and some big swings after that. Ideally XO should be closer to 80Hz due to localization of the lows right? But then my 60 – 110Hz gap starts to reappear again. Overall, the result is not very bad up to 130Hz it seems, after that some weird swings, but should I care?

Expecting I made quite a few beginner mistakes, but its fun to do and learn. Hope people have some tips / comments. And thanks for this great software!

 

[John Mulcahy]

Looks like a good result, well done. How does it sound?

 

[ParaWM]

Thank you. The bass does sound so much better with 2 subs and them properly aligned. I might be fussing too much about straight lines

 

[ParaWM]

I guess I have two main questions from this long story above. See my full sweep freq response below. Hope someone can shed some light:

1) I think I want to either put in a house curve and dont use Dynamic EQ on the AVR (red) or EQ it more flat and use DEQ (blue). Am I correct in thinking you dont't want to have both a house curve and use DEQ? We do often listen at -15 to -20 dB level.
2) The mains integration / level. I do have a big drop of 10dB going from 100 to 300Hz (green). Should I pull back the sub gain/SPL a bit to make that more even? Or is this quite common. It is what Audyssey came up with for the most part.