I do agree that I've heard speakers, and even cheap subwoofers that sound boomy as a consequence of their design. Not sure what causes this. Group delay? Distortion? My Monoprice 12s suffer from this, as do my Infinity R12s(to a lesser degree). I'd say almost all tower speakers I've heard as well as most sub $500 subwoofers I've heard suffer from this to at least some degree. IME, once you get to a certain level of subwoofer quality, with distortion, group delay, etc. all reduced to below audible thresholds, they all sound almost exactly the same once you equalize the position and response. I did a blind test between a Rythmik, JTR, and PSA subwoofer a few years ago. At first they did all sound slightly different, but once we put them in the same spot and EQed the response, none of us could tell them apart, and all of them were as "tight" and "controlled" as it possibly gets. Not saying there weren't still differences, but we couldn't hear them.
It definitely could be related to the sub itself, but imo, it's more likely due to the room. At those frequencies you're hearing the room
way more than you're hearing the speaker. The speaker actually matters very little in comparison. It's the room and the position that really matter.
@o2so , from your pictures, it looks like the Dyns and the SVS are in different rooms? If they're in different rooms, then that's your explanation
. That far below the rooms transition(Schroeder) frequency, you're hearing the room, speaker position, and speaker extension. Speaker quality has very little to do with it, imo. Directivity doesn't matter any more, and our ears are very insensitive to distortion and time issues.
Can you post frequency response graphs with a 50dB vertical scale? I think those would be useful, too, especially to see what's happening down super deep.
Also, a step response to see how well time aligned the subs could be helpful.
Assuming that the SVS and Dyns are in the same room, then I do see some differences in those CSD plots you posted, and based on those, I could forsee the Dyns sounding "faster", since they seem to decay faster. Fortunately(or unfortunately
), deep bass decay is more a function of the position and room, and has very little to do with the speaker/sub(once you get above that threshold). I think the most likely cause is probably one of two things:
1. Position
2. Speaker/Sub interaction
To test 1, move the SVS woofers into the exact location that the Dynaudio woofers are(you may have to raise them). Now remeasure and see what it looks like.
To test 2, something kinda hacky you could try is, disconnect the LS50s, then equalize the response of the Dyns and SVSs to the exact same target(with a lowpass and highpass in place) so that the Dyns are only playing up to as high as the SVS, and the SVS is only extending down as low as the Dyns.
Does that make sense?(I struggled trying to put that thought in to words
).
If it's the second one, then that is probably gonna be harder to solve. Second one is (imo) the primary reason why many people still opt for 2.0 with big tower speakers, despite the inherent limitations.
If it turns out to be neither of those, then perhaps
@Frank Dernie is right. I haven't seen group delay/distortion measurements for that sub, but usually those tend to be below audible thresholds(for decent subs). I know
@Sancus posted a graph the other day showing an SVS with subpar group delay measurements, but I don't remember which sub it was.
I still think it's one of those first two things, though. A good sub array should be better and more well "controlled" than basically any tower speaker, but it can often be difficult to realize that potential.