How to improve Clarity (C50) in Bass in (very) small Rooms

[Flaesh]

Is there such a thread on GS? My Google finds too many Clarity VX.

In the near field, a fairly high C(D) value at low frequencies is common\often.

My subs w\o xo measured in LP (somewhere about 4 meters from speakers) in 2019:

 

[ernestcarl]

Is there such a thread on GS? My Google finds too many Clarity VX.

Not a "clarity" specific thread. I just picked those three measurements out of maybe 30 or so different in-room measurements gathered from gearspace members.

My subs w\o xo measured in LP (somewhere about 4 meters from speakers) in 2019:

Pretty good considering the distance... my single sealed sub's front baffle distance to the couch's center MLP is about 3.6 m -- it ought to be really closer approaching 4 m when one is seated at the corner-end seating positions of the couch.



There's also a visible drop in the displayed clarity values at 50 Hz (and likely below); although, not nearly as much as yours due to the room acoustics itself.

 

[Tim Link]

Any technique designed to reduce decay time will also cause a spectral change. It is far more likely the ear is responding to that and not to decay as such. Particularly in small rooms where direct sound is in your face and there are strong specular reflections.

I read somewhere they tested people's ability to distinguish bass with decay from bass without by adjusting the levels to be the same in each case. Below 100 Hz it gets more difficult. Above 100 hz we're pretty sensitive to decay and resulting clarity issues.

There's a test you can do. Listen to the Musical Articulation Test Tones on headphones, and then listen through your speakers at the listening position. That makes it easy to determine if your room is reducing bass clarity in an audible way. You can find these tone bursts on Stereophile test CD2, or get it here: https://www.audiocheck.net/audiotests_matt.php

I've collected quite a few recordings of the MATT in different rooms, and in most rooms it's not possible to hear the bass at all frequencies as clearly as a human could discern it if the room were better. Another issue beside decay ruining clarity is early cancel reflections. You can't hear the initial sound very well if it's being largely canceled, but you can still hear the reverb. So it's really about the ratio of the loudness of the direct signal to the loudness of the reverb, not just the length of the reverb.

It can get more complicated. I had a bad early reflection cancel at around 200 Hz in my room, but the clarity still measured good there because the pulse just arrived late from other reflections. This made a bad looking kink on the spectrogram, but I could still hear clear pulses on the MATT test. I fixed it with absorption so the spectrogram straightened out. Honestly, I had a hard time hearing a difference in that case. So the spectrogram tells the truth, but it can be sometimes hard to interpret in terms of audible effect.