Dirac Live Bass Management?

[markus]

I rather get that “free bass” nuked by applying EQ afterwards than nuking it anyways without free bass.
If you are always loosing output by applying EQ why not compensate that loss with “free bass” ??

The problem is that all that "free bass" is largely from modal ringing. No EQ cut necessary if there's no ringing. Sorry, there is no free lunch when it comes to physics.

 

[QMuse]

The problem is that all that "free bass" is largely from modal ringing.

Not true, in the corner you gain wide LF boost. While it is true that this wide boost will increase modal peaks as well it is also true that they anyhow have to be EQ-ed and that is easy to do while the rest of the gain will remain there.

 

[markus]

Not true, in the corner you gain wide LF boost. While it is true that this wide boost will increase modal peaks as well it is also true that they anyhow have to be EQ-ed and that is easy to do while the rest of the gain will remain there.

That's not how it works at subwoofer frequencies. The room is way too small compared to wavelengths. A 20Hz sine wave has a wavelength of 17m (56').

 

[QMuse]

That's not how it works at subwoofer frequencies. The room is way too small compared to wavelengths. A 20Hz sine wave has a wavelength of 17m (56').

Wait, not that old myth that has been proved wrong at least a dozen times on this forum?!? Are you claiming that room can deliver gain only to those frequencies which are smaller than room's dimensions? If that is the case you need to do some reading about acoustics, actually quite a lot of it. Luckilly for you it has been discussed many times here, so just use search.

 

[markus]

Wait, not that old myth that has been proved wrong at least a dozne times on this forum?!? Are you claiming that room can deliver gain only to those frequencies which are smaller than room's dimensions? If that is the case you need to do some reading about acoustics, actually quite a lot of it. Luckilly for you it has been discussed many times here, so just use search.

Guess you're confusing topics here. Care to share a link to the topic you're alluding to so I can check if we are on the same page?

 

[QMuse]

Guess you're confusing topics here. Care to share a link to the topic you're alluding to so I can check if we are on the same page?

I don't think we are. Do your own research, it has been discussed in more than one topic here. Some basic knowledge about how standing waves are developing in room would also come handy.

 

[markus]

I don't think we are. Do your own research, it has been discussed in more than one topic here. Some basic knowledge about how standing waves are developing in room would also come handy.

You're deflecting. Your posts so far only seem to serve the purpose of attacking my character instead of addressing the topic. I've never said the "room can deliver gain only to those frequencies which are smaller than room's dimensions".

 

[QMuse]

You're deflecting. Your posts so far only seem to serve the purpose of attacking my character instead of addressing the topic. I've never said the "room can deliver gain only to those frequencies which are smaller than room's dimensions".

Not at all. You're wellcomed to explain in detail what you meant when you said this:

"That's not how it works at subwoofer frequencies. The room is way too small compared to wavelengths. A 20Hz sine wave has a wavelength of 17m (56'). "

 

[tecnogadget]

markus as promised, here is the Real McCoy

https://www.audiosciencereview.com/...urements-understanding-time-and-frequency.25/

 

[markus]

Not at all. You're wellcomed to explain in detail what you meant when you said this:

"That's not how it works at subwoofer frequencies. The room is way too small compared to wavelengths. A 20Hz sine wave has a wavelength of 17m (56'). "

You've said "in the corner you gain wide LF boost". That's not generally true. In the corner you couple energy to modes maximally. Whether or not a sub is able to pressurize the room ("room gain") doesn't depend on placing it in a corner.

 

[QMuse]

You've said "in the corner you gain wide LF boost". That's not generally true. In the corner you couple energy to modes maximally. Whether or not a sub is able to pressurize the room ("room gain") doesn't depend on placing it in a corner.

Well sure, let's first clear the basic terminology. When you put room in the corner what you are getting is boost in LF due to boundary reinforcement, not room gain (which is someting else). Boundary reinforcement works like this:

If you imagine a speaker is radiating high up a pole in the middle of a big field there are no boundaries to reinforce it. When you place it on the floor you are radiating into half space and get +3dB gain. Add a wall perpendicular to the floor and it's quarter space and another +3dB. Finally add another wall so the speaker is now in a corner and you are in eighth space with another +3dB.

As for room gain, it is totally different phenomena and it occurs when the wavelength being produced by the speaker is the same as a half-wavelength of the room, and the driving mode changes from wave mode to pressure mode. This can only occur if walls are solid enough and there are no leaks or openings. The curve will depend on how lossy the room is and the individual dimensions, but a well sealed room can yield 12dB/oct slope from the half-wavelength frequency.

 

[markus]

markus as promised, here is the Real McCoy

https://www.audiosciencereview.com/...urements-understanding-time-and-frequency.25/

Thanks. The content of that post isn't news to me and it also isn't contrary to what I've said so far. So I'm not sure what you guys are arguing about.

 

[QMuse]

Thanks. The content of that post isn't news to me and it also isn't contrary to what I've said so far. So I'm not sure what you guys are arguing about.

Do you care to explain what you meant by this?

"The room is way too small compared to wavelengths. A 20Hz sine wave has a wavelength of 17m (56'). "

 

[markus]

Well sure, let's first clear the basic terminology. When you put room in the corner what you are getting is boost in LF due to boundary reinforcement, not room gain (which is someting else). Boundary reinforcement works like this:

If you imagine a speaker is radiating high up a pole in the middle of a big field there are no boundaries to reinforce it. When you place it on the floor you are radiating into half space and get +3dB gain. Add a wall perpendicular to the floor and it's quarter space and another +3dB. Finally add another wall so the speaker is now in a corner and you are in eighth space with another +3dB.

As for room gain, it is totally different phenomena and it occurs when the wavelength being produced by the speaker is the same as a half-wavelength of the room, and the driving mode changes from wave mode to pressure mode. This can only occur if walls are solid enough and there are no leaks or openings. The curve will depend on how lossy the room is and the individual dimensions, but a well sealed room can yield 12dB/oct slope from the half-wavelength frequency.

You're generally comparing free field behavior to putting a source into an enclosed space. But the topic at hand is placement of a low frequency source (first constraint) within an enclosed space (second constraint) at different locations.

 

[QMuse]

But the topic at hand is placement of a low frequency source (first constraint) within an enclosed space (second constraint) at different locations.

And that is exactly what boundary reinforcement and room gain is all about.

Once again, why don't you explain what you meant when you said ""The room is way too small compared to wavelengths. A 20Hz sine wave has a wavelength of 17m (56'). "

So far you've been avoiding to explain that in 3 consecutive posts .

 

[RichB]

Well, you get free bass at the expense of max. ringing and max. pressure minimas. While this might work in some rooms (with EQ) it's not the best approach in each and every room. At the upper end of the subwoofer frequency range the response is no longer minimum phase. So I don't think putting a single subwoofer in the corner can be a general recommendation. Especially if you want it to work not only for one single listener.

There are rooms with more than one corner
If the room is small, there will be pressure build-up with bass, no matter where it comes from.
Most have limited choice for placement. Multiple subs make sense, when possible, and they are extremely impractical in my room.

...and all that "free bass" gets nuked by applying EQ afterwards.

And then, there is greater headroom for equalization at other frequencies.
There is no cure-all, and none was suggested.

- Rich

 

[markus]

And that is exactly what boundary reinforcement and room gain is all about.

Once again, why don't you explain what you meant when you said ""The room is way too small compared to wavelengths. A 20Hz sine wave has a wavelength of 17m (56'). "

So far you've been avoiding to explain that in 3 consecutive posts .

I said this because at LF the behavior is best described in terms of sound waves, not rays. Your example is rooted in the latter. There is no "boundary gain", just different energy coupling to modes depending on location.

 

[markus]

And then, there is greater headroom for equalization at other frequencies.

Compare measurements from real rooms and then let's talk again

There is no cure-all, and none was suggested.

- Rich

Well, Flavio did and that's where this unfortunate "discussion" emanated from.

 

[RichB]

Compare measurements from real rooms and then let's talk again

Well, Flavio did and that's where this unfortunate "discussion" emanated from.

A strange position for the "Dirac Live Bass Management" thread to be coming from Dirac

- Rich

 

[QMuse]

I said this because at LF the behavior is best described in terms of sound waves, not rays. Your example is rooted in the latter. There is no "boundary gain", just different energy coupling to modes depending on location.

Well, I provided the explantion for term "boundary reinforcement" , which btw is very well known to anyone dealing with the acoustics, but I certainly cannot force you to understand it and accept it. Judging by what you said that it is related to rays and not to audio waves I believe it's time we agree that we disagree as I have nothing more to add to what I have already said.