Simulation Overview of the 'Double Bass Array' Configuration.

[OCA]

I think not! VPDBA (sometimes and somwhere wrong called SBA) deserves fair criticism and exposure))
To be honest ever arbitrary placed VPDBA (APVPDBA ) "kills" first lenght mode:
View attachment 250615

More or less suitable room is desirable for simple 2channel DBA, while some unperfections may be compensated by EQing subs individually.
Can you show your room drawing?

The red line is an opening to dining room with no door (old German flat). I have two Focal Air subs at opposite corners but I don't use them in the hifi system. The speakers placement and LP are accurate in the drawing.

 

[Flaesh]

a door opening in the middle of the rear wall and there's no door

I measured mine (link in signature) with closed\opened doors and windows, all affects the result but in generally it measured and heard DBA-ish)).
With opening in the middle you need 4 subs.

 

[OCA]

I measured mine (link in signature) with closed\opened doors and windows, all affects the result but in generally it measured and heard DBA-ish)).
With opening in the middle you need 4 subs.

My focal subs are useless as subs, my mains go lower than them but they are quite easy to hang on a wall, actually they're designed for that. I will think about this. Your bass reponse is flat down to like 12Hz, never seen or heard that kind of bass before

 

[Flaesh]

Your bass reponse is flat down to like 12Hz, never seen or heard that kind of bass before

It sounds good)). Eliminating wide deeps and associated time anomalies improves articulation and so on; pay attention to the subs, they are not for the anechoic space.
Germany seems most DBA\*SS (*source to sink) country, may be you can find another's system to listen to.

 

[mumford]

Does the matrix in the front wall need to be the same as the back wall? Let say I have a 4x3 matrix (12 subs) on the front wall, and as the back wall needs maybe 6db or more in attenuation, any ill effect if I use a 3x3 matrix (9 subs) in the back wall?

 

[Flaesh]

to be the same

Not necessary.

as the back wall needs maybe 6db or more in attenuation

May be in very absorptive room. Normally far less attenuation.

 

[René - Acculution.com]

I am not trying to argue that this response shape can be predicted from the radiation of a piston in an infinite baffle into half-space. My question was about the nature of the stimulus used in the simulation itself.

So why should I care about "radiation of a piston in an infinite baffle into half-space" then? Because that's how the on-axis pressure at a point at distance d from the piston is calculated using the Thiele/Small theory. For an ideal sealed or infinite-baffle subwoofer with zero voice-coil inductance, in the T/S theory the passband is the frequency region for which the acceleration amplitude is constant with frequency.

For such a sub, with an applied voltage having a constant amplitude vs. frequency:

• The displacement amplitude vs. frequency has a low-pass characteristic
• The velocity amplitude vs. frequency has a bandpass characteristic
• The acceleration amplitude vs. frequency has a high-pass characteristic (same as the pressure response of the sub itself)

This nature then becomes relevant when such a sub is placed in multiples in a DBA. One might rightly wonder how the subs' response according to the T/S theory is modified by the DBA. I would argue that, to determine such an effect, such a simulation would best be done with a stimulus having a constant acceleration amplitude with frequency.

The slope in my response is there because I applied constant acceleration. That will only hold above the resonance frequency of the sub. For a flat response, velocity is needed, since in this ‘infinitely long tube situation’ created by the DBA setup, the acoustic impedance seen from the subs is resistive.

 

[Flaesh]

about flush mounting:

 

[René - Acculution.com]

It should be noted that near the subwoofers, the field is not planar, even when flush mounted.

 

[Flaesh]

near the subwoofers, the field is not planar, even when flush mounted.

This is obvious (generally). But your pic is good, especially the delicate glamorous colors; not like primitive 2D red-blue

from Hresp simulation.

What do you think about subs faced to wall?..

 

[René - Acculution.com]

This is obvious (generally). But your pic is good, especially the delicate glamorous colors; not like primitive 2D red-blue
View attachment 268497
from Hresp simulation.

What do you think about subs faced to wall?..
View attachment 268496

I haven’t tried, but the change in acoustic impedance could change the displacement of the driver if the gap is small, and so the simulation requires a little more input. I would think that the field is still not planar but out in the room it doesn’t matter.

 

[Flaesh]

the change in acoustic impedance could change the displacement of the driver if the gap is small, and so the simulation requires a little more input

I had rear subs pointed toward the wall in my second DBA with IB front subs

I didn't carefully measure the difference with the usual arrangement, but overall the system worked fine enough. IIRC the gap was about 2"-3".
IIRC member @dasdoing uses subwoofers (not DBA) facing the wall with a slight gap.
Now one buddy is going to try DBA, 2+2 (4+4 perspectively) 12" drivers, up to 100 l boxes:

Aesthetically invisibility of cheap drivers may be good and psychoacoustically invisibility of transducers may(??) be bad for him.

ps: It’s a mystery to me: how audiophiles, who hear a huge difference, for example, in wires, hear sound worse if they don’t see cardboard cones

 

[Adi777]

DBA or SBA? Cinema room size: 4m x 6m.

 

[withoutsuit]

Unless you want to spent space for many basstraps: DBA

 

[Keith_W]

Do DBA's only kill room modes, or can they tackle ringing as well? Does anybody have a waterfall graph to share?

 

[withoutsuit]

As both is related together, it kills reverberation and therefore the SPL of your room modes.

 

[Flaesh]

waterfall graph to share?

added in my tread

 

[tmuikku]

Hi all, how is envelopment with DBA? Reading Griesinger presentation http://www.davidgriesinger.com/laaes2.pdf it says there needs to be multiple LF sources (<200Hz) for enough ITD fluctuations for envelopment, preferably to side of the listener, single one in front of listener doesn't do it. Is this something relevant here, or is the DBA just better even if there isn't envelopment for lows? or is there?

If this is something to improve on, would it work having the arrays on the side walls outputting L and R sound respectively and also cancelling each other out like in the standard setup between front and back wall?

 

[Flaesh]

DBA or SBA?

Briefly answer - DBA or SBA.
In a passband D works better, than moderate sized S.
Also "hybrid" forms may exist))

 

[Flaesh]

Reading Griesinger

Have you heard to such system? IIRC one audioholic tried this; his report isn't very encouraging.
About the front bass of D(S)BA has been written repeatedly.
I don't know anything about real world implementations of a stereo *bass array. Do you want to try?))