Great room measurement but should I change Dirac's bass roll-off?

[seedragon]

I got a great measurement (L+R at MLP) after running Dirac Live Bass Control.

However, I'm pretty sure my subs (dual 15" ported) can reach lower than that where Dirac set the bass roll-off: ~16 Hz.

Can/should I open that up to increase extension, or will that create issues?

I might just open it up anyway to see what happens but I wanted to know if there is some theory behind why Dirac set the roll-off at that point, e.g., to protect headroom, etc.

EDIT: I should mention that I mostly watch movies and love bass. When I listen to music, I listen to bass-heavy music.

 

[HarmonicTHD]

I got a great measurement (L+R at MLP) after running Dirac Live Bass Control.

However, I'm pretty sure my subs (dual 15" ported) can reach lower than that where Dirac set the bass roll-off: ~16 Hz.

Can/should I open that up to increase extension, or will that create issues?

I might just open it up anyway to see what happens but I wanted to know if there is some theory behind why Dirac set the roll-off at that point, e.g., to protect headroom, etc.


View attachment 338066

Looks good.

At 16Hz and below not much is happening usually and you usually get over proportional distortion. I mean you can try.

 

[staticV3]

For most music there's not much point in extending the bass response any deeper IMO.

For movies or shows, there would only be a point if you can also apply BEQ: https://www.avsforum.com/threads/bass-eq-for-filtered-movies.2995212/

 

[Vacceo]

To be honest, if you´re not playing a lot of organ music or film (and not even all films), below 20hz should not be something to be worried about. Even in those cases, infrasonics are great to have, but since you feel them, not listen to them, it does not matter much as long as they are present.

 

[seedragon]

I removed the bass roll-off in Dirac Live BC. I got meaningful output down to 12 Hz but didn't like how it sounded. With bass-heavy movies like Pacific Rim, there was just too much bass—my ability to differentiate sounds in the sound field plummeted. I almost felt like I was sitting inside of a subwoofer.

That said, based on the measurement, the bass was also at a much higher level than my previous correction. I chalk that up to DLBC's genetic algorithm.

I plan to try removing the roll-off again, but this time with a lower bass boost, and see how it sounds.

 

[kemmler3D]

there was just too much bass—my ability to differentiate sounds in the sound field plummeted. I almost felt like I was sitting inside of a subwoofer.

Yep, the bass is at 10dB over the mids which is probably a better explanation than too much extension. If you level it out so it hits around 80dB at 20hz it should be a good starting point.

Not sure about movies, but most music will be rolled off at or above 20hz anyway to preserve headroom for more audible sounds.

I personally actually don't hear below 20hz, really. I know my headphones can go below 20hz, but if I put on a 15hz tone and crank it up, I don't really hear anything (beyond air whooshing) and I just get a weird sense that the walls are shaking. (weird because it's headphones...)

The distortion point is also a good one. If you are going down to 16hz or but with high distortion, what you mostly hear is 32, 48, 64hz, the fundamental might just be vibrating stuff in the room, but not be perceived as sound.

 

[rynberg]

I got a great measurement (L+R at MLP) after running Dirac Live Bass Control.

However, I'm pretty sure my subs (dual 15" ported) can reach lower than that where Dirac set the bass roll-off: ~16 Hz.

Can/should I open that up to increase extension, or will that create issues?

I might just open it up anyway to see what happens but I wanted to know if there is some theory behind why Dirac set the roll-off at that point, e.g., to protect headroom, etc.

EDIT: I should mention that I mostly watch movies and love bass. When I listen to music, I listen to bass-heavy music.

Why do you think they go lower? The PSA 15V is 3dB down at 20 Hz with a 4th order slope below that (-24dB/octave). It looks like you have a bigger room and you have a little room gain below 20 Hz (you only show an -18dB/octave drop-off). I think you've got what you got. It's a reasonable-sized <$1,000 sub, it's a bit much to expect strong output at 16 Hz, even with two of them.

 

[staticV3]

Here's the frequency response graph of Pacific Rim's soundtrack:

Red is AVG, green is Peak.
Dashed is the original, solid is with BEQ applied.

Like most movie soundtracks, Pacific Rim's is high-passed at ~20Hz, so I doubt that increasing the LFE from 16 to 12Hz was what caused the boomy sound.

 

[seedragon]

Here's the frequency response graph of Pacific Rim's soundtrack:
View attachment 340616
Red is AVG, green is Peak.
Dashed is the original, solid is with BEQ applied.

Like most movie soundtracks, Pacific Rim's is high-passed at ~20Hz, so I doubt that increasing the LFE from 16 to 12Hz was what caused the boomy sound.

That makes sense. I agree that the boominess was probably a level issue, not an extension issue.