What method of bass management do you use?

[Keith_W]

I think that bass management is even more important than what subwoofers you buy. IMHO, the only considerations for what subwoofer you buy is whether it produces enough bass, goes as low as you want, and has features that you want (e.g. servo control, price, aesthetics). Even ported vs. unported subs is less important than bass management. This is because the moment the sub is placed in a room, it is the room that dictates the performance of the sub. 

 

I watched a video with an interview with Trinnov's Jon Herron discussing their new bass solution. Most of the discussion was about Trinnov's "waveforming" technology - for me it was a fantastic video and I recommend watching the whole thing. However, this slide was of particular interest and I would like to see what SNA members think of it.

 

 

Link to video (timestamped 33:50). 

 

There are some bass management strategies that Jon Herron does not mention. For completeness, I have included it in the poll. These are the options: 

 

No bass management. Speakers and subs are placed in the room and allowed to do its thing. Because of long wavelengths, room modes / standing waves, this method produces lumpy bass that varies from seat to seat. Note that if you do not have room treatment specifically designed to tackle bass frequencies, e.g. thick absorbers, membrane traps, or Helmholtz resonators, you belong in this category. 

 

Room treatment. Usually intrusive and ineffective. The trap needs to be quarter wavelength of the lowest frequency desired to work effectively (this is because a half sinewave needs to fit in the absorber, but because it reflects from the wall, the half sinewave is halved again, producing a quarter wave). A 100Hz wavelength is 3.4m, so your absorber needs to be 85cm thick. If you want to attenuate lower frequencies than this, it needs to be even thicker, e.g. 40Hz has a wavelength of 8.6m. There are less intrusive types such as membrane absorbers. Remember that anechoic chambers are not anechoic below 80Hz. Sometimes, room features can be used to take advantage of bass management, e.g. my listening room has a huge sliding door behind the listener that can be opened to the backyard. There is an audible and measurable difference when the doors are open. The disadvantage of course, is that the room noise floor is raised, it gets bloody cold in winter, and I can't do it at night out of consideration for my neighbours. 

 

Flood the room with reflections. This involves multiple subwoofers, sometimes with DSP (e.g. Multi-Sub Optimizer). The goal is to even out the bass response by flooding the room with reflections, creating what Jon Herron calls "a cacophony of sound". I am not sure, but I think that Room Shaper has the same approach. 

 

Control the bass. The goal is to calculate or measure the reflections and use the subwoofer/speakers to cancel the reflections at the listening position, or steer bass away ("waveforming") into adjacent rooms. I tried such an experiment in my thread with a bass phased array but was not successful (notwithstanding a certain member trying to tell me that such an approach is impossible in domestic listening rooms ... well, Trinnov does it). Examples include Dirac ART, Trinnov, double bass arrays, and virtual bass arrays. Such an approach results in wasted subwoofer power, because half the output is used to create cancellation. But if it works, it results in more even bass, less seat to seat variation, and less ringing. 

 

Bass equalization. Simply lops off the peaks when measured at the listening position. This can create problems elsewhere in the room, and does not do much for seat to seat variation unless you have a favourable room configuration. A bit of bass equalization is usually needed on top of the other strategies because none of them are completely effective. Bass EQ can be accomplished via DSP or with old fashioned analog equalizers, although the latter approach seems to be rare. 

 

I use a combination of bass control, bass EQ, and "room treatment" (open sliding doors). I am curious what SNA members use? 

 

Edited August 14 by Keith_W

[Mika75]

I eq using the Behringer DCX, it's "setup" function automatically corrects delay and polarity of fronts to stereo subs. (Pink noise sequence with mic attached)

Without this I feel it's virtually impossible to get accurate phase response i.e Front L 10.01mS, Front R 9.87mS, LSub 0mS, RSub 1.69mS

[GregWormald]

No subwoofers, but the main speakers have a good response to 17Hz. Dirac Live Room Correction is used to manage the full range response.

[aussievintage]

I voted other.  I keep speakers and listeners well away from walls.  Nearly all sound being heard is direct from the speakers.  Only problem with bass is, in my downstairs room, there's a wall panel that rattles       

[cazzesman]

Rear corner acoustic panels and Dirac Live curve with an additional DL minor tweak for a small dip around 50ish.  

 

Regards Cazzesman

[murrmax]

Quote

1. What method of bass management do you use?

 

The volume knob

[stereo coffee]

I enjoy immensely, what is already correctly  present and easily reproduced within music. The video was IMO wrong and misleading with its approach. 

Edited August 19 by stereo coffee

[aechmea]

It's the lounge room but has always been thought of as the "music room".  Rarely (never) used as a lounge room.

Single listening chair so seat-to-seat variation is not a consideration/issue

 

Speaker correction (DEQX)

Multiple bass sources (speakers full range plus subs)

Careful placement (end result placement is a bit weird but it works)

EQ to lop off peaks and adjust amplitudes (DEQX)

Large and intrusive quantity of absorption and tubes = dead back wall

Skyline diffusion on front wall (not for bass)

Carpet, curtains and large plush furnishing = few reflective surfaces

 

Edited August 19 by aechmea

[Satanica]

Just so we are all on the same page, what frequency range is "bass" ?

[playdough]

2 hours ago, Satanica said:

what frequency range is "bass

Sub could be up to 20Hz, bass could be up to 150Hz ?

 

Large wall shorting MLV membranes and structural bolstering as ULF < 25Hz and bass management, a range of surface treatments, inc, cieling/wall absorbers and diffusers.

 

Yet to apply any digital counter measure.

Edited August 20 by playdough

[Keith_W]

2 hours ago, Satanica said:

Just so we are all on the same page, what frequency range is "bass" ?

 

20Hz to your Schroder frequency, which is room dependent. Usually 100-140Hz depending on your room size. 

[Satanica]

2 minutes ago, Keith_W said:

 

20Hz to your Schroder frequency, which is room dependent. Usually 100-140Hz depending on your room size. 

 

Why not lower than 20Hz? I apply room correction all the way to 12Hz cause I still have output down there. I treat 12Hz the same as 60Hz.

 

Wikipedia says bass is 16Hz to 250hz. 

https://en.m.wikipedia.org/wiki/Bass_(sound)#:~:text=Bass (%2Fbeɪs%2F,range C2-C4.

[Keith_W]

Perhaps I should have said "whatever is the lowest frequency your system can reproduce" to avoid nitpicking 

[Satanica]

1 hour ago, Keith_W said:

Perhaps I should have said "whatever is the lowest frequency your system can reproduce" to avoid nitpicking 

 

I'm actually more interested in what the upper frequency is. Subject to change, I'm going with 250Hz.

Edited August 20 by Satanica

[stereo coffee]

22 minutes ago, Satanica said:

 

I'm actually more interested in what the upper frequency is. Subject to change, I'm gong with 250Hz.

The references for what frequencies are bass in nature ,  suggest as assessing orchestral instrument ranges, and upper frequencies are typically 700 hz, there,  but can extend much higher with as example with jazz playing  into the midrange . A typical speaker crossover for a three way is to 500hz with bass drivers   demonstrating where bass with upper range is useful reproduction.

 

Dave Holland or Ron Carter  example seasoned jazz players. and many hours listening to each will confirm frequency ranges. Dave is so well respected and at the same time respectful of other players , its always an education listening to him  https://daveholland.com/

[Keith_W]

I'll put it this way - bass management is only relevant up till Schroder. Above Schroder, maybe up to 4x Schroder, a different strategy is required. Regions which are non minimum phase become more prevalent and so become difficult to correct if you do not have the right tools. @Satanica 250Hz is probably within the transitional band of your room, but to really know what that is I need your room volume and T30. 

[rand129678]

8 minutes ago, Keith_W said:

Regions which are non minimum phase become more prevalent and so become difficult to correct if you do not have the right tools.

 

Is this 'complex smoothing' ?

 

P. Hatziantoniou, J. Mourjopoulos, and J. Worley, "Subjective Assessments of Real-Time Room Dereverberation and Loudspeaker Equalization," Paper 6461, (2005 May.). doi:

Abstract:
Formal subjective tests of real-time room dereverberation using Complex Smoothing were conducted to assess the robustness and the validity of the method under real sound reproduction conditions. For comparison, anechoic, inverse loudspeaker real-time filtering was also subjected to assessment to decouple improvements due to the complex smoothing inverse room filtering and due to mere equalization of the loudspeakers. Results derived from a multivariate analysis of variance (MANOVA) of the test data, verify the conclusions detected in the past by the objective evaluation of the method e.g. significant improvement in sound quality and immunity to real-time processing artifacts independently of room size and listener position.

[stereo coffee]

7 minutes ago, Keith_W said:

I'll put it this way - bass management is only relevant up till Schroder. Above Schroder, maybe up to 4x Schroder, a different strategy is required. Regions which are non minimum phase become more prevalent and so become difficult to correct if you do not have the right tools. @Satanica 250Hz is probably within the transitional band of your room, but to really know what that is I need your room volume and T30. 

But it is the instrument that creates the bass frequency. Assessing the cause and capability of frequency enables to correctly assess its ability onward from and including the source component. You don't need to correct anything at all , all that is needed is to preserve the source audio .    

[Keith_W]

31 minutes ago, stereo coffee said:

But it is the instrument that creates the bass frequency. Assessing the cause and capability of frequency enables to correctly assess its ability onward from and including the source component. You don't need to correct anything at all , all that is needed is to preserve the source audio .    

 

Ummmm, I really don't know what to say. If you were a newbie, I would try to help you. But you are not, and you should know better. If you are genuinely keen to learn, I am happy to point you to some resources. Otherwise, what I have seen from you in other threads tells me that it is wiser to simply ignore you. 

[Keith_W]

40 minutes ago, rand129678 said:

 

Is this 'complex smoothing' ?

 

P. Hatziantoniou, J. Mourjopoulos, and J. Worley, "Subjective Assessments of Real-Time Room Dereverberation and Loudspeaker Equalization," Paper 6461, (2005 May.). doi:

Abstract:
Formal subjective tests of real-time room dereverberation using Complex Smoothing were conducted to assess the robustness and the validity of the method under real sound reproduction conditions. For comparison, anechoic, inverse loudspeaker real-time filtering was also subjected to assessment to decouple improvements due to the complex smoothing inverse room filtering and due to mere equalization of the loudspeakers. Results derived from a multivariate analysis of variance (MANOVA) of the test data, verify the conclusions detected in the past by the objective evaluation of the method e.g. significant improvement in sound quality and immunity to real-time processing artifacts independently of room size and listener position.

 

God only knows what proprietary algorithms Bernt (Audiolense) and Uli (Acourate) use for correcting upper frequencies. I sent you a link to another forum where Uli discusses Minimum Phase correction. Further in the same thread, he notes that Acourate uses a "powerful and proprietary algorithm" that allows correction of non minimum phase regions. It may well be based on this paper, or it may not, and you know my private thoughts on this so no need to repeat that here because this thread is about bass correction and not correction of non minimum phase regions. 

[stereo coffee]

4 hours ago, Keith_W said:

 

Ummmm, I really don't know what to say. If you were a newbie, I would try to help you. But you are not, and you should know better. If you are genuinely keen to learn, I am happy to point you to some resources. Otherwise, what I have seen from you in other threads tells me that it is wiser to simply ignore you. 

Lovely,  but.. as can be seen i am relating bass frequencies to musical instruments, rather than something intangible, that IMO has no relationship to what is then played.   Can you name any musical pieces or instruments, you have heard  that relate to bass management ? 

[Keith_W]

If you are asking why it matters, this is why: 

 

 

Well, there is Bach's Passacaglia in C Minor, BWV 582. Pipe organ goes down pretty low. You want to hear every note in the foot pedal with none of them sounding louder than the others. That is the digital output from JRiver. You can see that there is still a lot of LF output at 20Hz. 

[sir sanders zingmore]

17 minutes ago, stereo coffee said:

Lovely,  but.. as can be seen i am relating bass frequencies to musical instruments, rather than something intangible, that IMO has no relationship to what is then played.   Can you name any musical pieces or instruments, you have heard  that relate to bass management ? 

@stereo coffee please do not drag this topic off topic. 

[stereo coffee]

15 minutes ago, Keith_W said:

If you are asking why it matters, this is why: 

 

 

Well, there is Bach's Passacaglia in C Minor, BWV 582. Pipe organ goes down pretty low. You want to hear every note in the foot pedal with none of them sounding louder than the others. That is the digital output from JRiver. You can see that there is still a lot of LF output at 20Hz. 

Thank you, I will obtain it on CD , to ascertain its reproduction.

[davewantsmoore]

On 14/8/2023 at 11:57 AM, Keith_W said:

I would like to see what SNA members think of it.

Using speakers as absorbers (like Trinnov are doing here, and like Dirac Live ART) is very cool.

Needs a lot of sources at LF, to be very effective (in "steering", if you think about the 2 sources at 50hz example like you went through in your thread, the source interaction is very small compared to the omni-direction nature of those sources --- ie. the bit of their SPL that didn't interfere, at least not in the way you intended/wanted).

 

   ... and is not obviously trivial to figure out (eg. Trinnov guys taking 96 measurements in a room, eeeek).

 

It's the way of the future (more speakers can alway be helpful, if you're clever).

 

 

On 14/8/2023 at 11:57 AM, Keith_W said:

I am curious what SNA members use? 

Many sources

EQ vs multiple seats

"Active" cancellation of modes (ie. delay vs frequency vs position to cancel peaks and dips)

For <80Hz

 

I also have experimented a lot with "flanking woofers" type techniques , (including combinations of monopoles and dipoles), to try and cancel sidewall and front wall, and floor reflections in the 80 to 200Hz zone..... all the same sort of thing as what Trinnov and Dirac are doing (just obviously theirs is much much more sophisticated.   It works quite well.... and there is a lot of information there in most music, so it is good.

 

11 hours ago, Satanica said:

Just so we are all on the same page, what frequency range is "bass" ?

 

<100Hz <shrug>

 

... but for this discussion I think all frequency up to where the room stop controlling the sound are relevant, so 200Hz... even 300Hz.

 

52 minutes ago, stereo coffee said:

Can you name any musical pieces or instruments, you have heard  that relate to bass management ? 

Reproducing bass, has nothing to do with what made the bass sound.  click, tap, drum, thud, organ, tank, whatever.