Never Put Subwoofers In Corners... Even with DSP and Multi-Sub Setups?

[Bjorn]

Hello again. Some of these terms are new to me but one thing thats for sure is that what DBA is, or how one is set up, isn't analogous across the diy community.

My understanding was that a DBA involved flush mounted woofers on front and rear wall, time aligned at the listening point across the width of listening space... on the other forums I've been learning about another approach where they are placing woofers front and back wall symmetrically and using the rear woofers to cancel out the signal coming from the front... from there, they use peak eq filters to further tailor the FR.

I do not know the capabilities of a single bass array (SBA), could you please elaborate on the set up of such a thing? Does this imply flush mounting? Would a large MTM be considered a bass array?

While DBA is the double array with delay, SBA is just the single array of woofers on the front wall with massive dampening of the rear wall. This will give a much better response and time domain behaviour higher up in frequency vs DBA.

Quality of the low frequency is more than just a good deep bass response. The mid and upper bass and low midrange is actually more important as we more sensitive to this range. Something that the multiple subwoofer approach doesn't adress and is one if its major weaknesses. DBA can go higher in frequency than traditonal multiple subwoofers depending on the number and proximity of woofers used in the array, but SBA will work much higher. And as mentioned previously SBA can be combined with diffusion which is IMO very import psycoacoustically. Just as speakers though, the quality of the directivity of the diffusers is important

 

[FeddyLost]

I don't understand. So a lot of people want to say that you don't need to do acoustics in the listening room/cinema, if you want to have great quality bass, just buy a cheap DSP + 2/4 subwoofers and that's it? It's a bit hard to believe. DSP is supposed to be better than a professionally prepared acoustic adaptation? Isn't that just wishful thinking?

In fact, DSP+multisub is the only good solution if you need something transportable and liquid investment.
Purely architectural/acoustical solution generally work much better only if you are building control room from scratch. This effectively prevents ordinary customer from going this way.
It's almost like dilemma between Uber and good ol' personal S-klasse.

 

[DRNNOO]

The mid and upper bass and low midrange is actually more important as we more sensitive to this range.

One of the reasons I chose the Acoustic Elegance18H+ for my bottoms.

This will give a much better response and time domain behaviour higher up in frequency vs DBA.

This is more encouragement to try active cardioid first, directivity remains the real bread winner.

 

[sigbergaudio]

I don't understand. So a lot of people want to say that you don't need to do acoustics in the listening room/cinema, if you want to have great quality bass, just buy a cheap DSP + 2/4 subwoofers and that's it? It's a bit hard to believe. DSP is supposed to be better than a professionally prepared acoustic adaptation? Isn't that just wishful thinking?

Where did anyone say that, exactly?

 

[Chromatischism]

This is more encouragement to try active cardioid first, directivity remains the real bread winner.

The experiments I've seen with cardioid ended up acknowledging that its cons outweigh the pros. The cons being the loss of a lot of output, which isn't linear over the frequency range. A lot of thought has to go into a good cardioid system. And the pros, which purportedly are less room interaction, can much more easily be achieved by multiple subs and EQ. So at this point I remain unconvinced it's a practical solution.

 

[Adi777]

Where did anyone say that, exactly?

Okay, I wrote this wrong. You are right.

 

[napfkuchen]

In my room the subwoofer needs to be placed in the corner, there is no other option. After calibration the frequency response is fine.

But as room dimensions are small (4 * 3,60 * 2,65 m) and it lacks any proper treatment reverb is problematic. Won't show you the RT60-graph though ... too embarrassing.
It's like the room is screaming at me: "I need absorbers NOW!"

 

[abdo123]

Here is a graph that compares the FR of a single sub (with EQ) with three subs (with EQ) and it shows a pair of nulls at 66Hz and 84Hz that are reduced in sharpness and depth (by 22dB and 16dB respectively) resulting in an overall smoother FR.

From: https://www.stereophile.com/content/jl-audio-fathom-f110v2-powered-subwoofer-measurements

I don't know if someone said this yet. But three subwoofers are worse than both two subwoofers and four subbwoofers from reading welti's paper. I would avoid it.

 

[Willem]

three subwoofers are worse than both two subwoofers and four subbwoofers from reading welti's paper

Geddes would disagree, and he is not alone.

 

[Chromatischism]

Geddes would disagree, and he is not alone.

Geddes did not do multi subs equalized together.

 

[Willem]

I am not quite sure how he equalized them, but I would always combine multisubs with something like MSO rather than general equalization.

 

[Bjorn]

Three subwoofers without mains. No smoothing or equalization. Seems like that can work as well.

 

[radix]

Arendal recommends putting their side-firing sub in a corner, or at least starting out there. They also recommend that if you get multiple subs, stack them in the corner.

From their 2020 series sub manual:

Arendal Sound therefore recommend starting with a front corner placement. Try to use the corner with the most solid structure - usually brick or block, or if in a timber framed construction....

and

The optimal position for a second subwoofer, is co-located on top of the first one. This is true, even if you can’t put the first one in a corner. The second best position is co-located next to the fi rst one.

What do you think of this advice?

 

[Chromatischism]

What do you think of this advice?

It's bad advice. The advantages of distributed subs are well known.

 

[abdo123]

Three subwoofers without mains. No smoothing or equalization. Seems like that can work as well.
View attachment 266057

Ofcourse it works, it’s just the response is more uneven across multiple seats than just two subs.

 

[My adventures in stereo]

Geddes did not do multi subs equalized together.

Geddes method, suggests phase alignment without time alignment

 

[Digital_Thor]

In my room the subwoofer needs to be placed in the corner, there is no other option. After calibration the frequency response is fine.

View attachment 265954

But as room dimensions are small (4 * 3,60 * 2,65 m) and it lacks any proper treatment reverb is problematic. Won't show you the RT60-graph though ... too embarrassing.
It's like the room is screaming at me: "I need absorbers NOW!"

Would also be nice to see the summation with your mains. Works pretty well here, if I use 12dB Butterworth on the mains at 70 Hz and 48dB LR at 90-110 Hz with the subs. The overlap smooth out that deep suck out that usually occur at the crossover.
I believe my "soft" wooden floor helps with fewer annoyances with bass in my apartment.

 

[Digital_Thor]

I am not quite sure how he equalized them, but I would always combine multisubs with something like MSO rather than general equalization.

You can go very far with individual gain and phase of each sub. When that works - minimum suck out and dips... then you EQ the excess energy globally.

To me MSO is extremely over-complicated, and I have not had it work just remotely as well as just looking at measured curves, and doing it manually, until I had a smooth sum in total.

 

[DRNNOO]

The experiments I've seen with cardioid ended up acknowledging that its cons outweigh the pros. The cons being the loss of a lot of output, which isn't linear over the frequency range. A lot of thought has to go into a good cardioid system. And the pros, which purportedly are less room interaction, can much more easily be achieved by multiple subs and EQ. So at this point I remain unconvinced it's a practical solution.

I read that as; "I created an active cardioid situation where I did not have enough headroom"

I wonder if 4 18" woofers per side would be enough, I am only listening at 1m. I just want to make sure I can still hit 115db/1m within xmax. In my opinion, when a null is removed....that is restoration of headroom. I would like to that that because of the way I intend to position the woofers, mixed phase of monopole and cardioid will allow me to fine tune to a better result in any situation. I am really interested in cleaning up midbass like was suggested by Bjorn. The way I intend to set it up, when I show an example I think you say "oooh, ok" lol.....or maybe not lol. I am planning to use side firing woofers for the cardioid woofer. As monopole, I will be limited by the baffle width is all...and thats fine too.

 

[Bjorn]

Cleaning up the midd and upper bass requires acoustical treatment. There's simply no way around this if one wants a stellar time domain behaviour, and which is crucial for a great result.