DBA (Double Bass Array) - marketing?

[Vladimir Filevski]

In most cases, this will be done by moving the subwoofer a little.

In most cases, the optimal position for subwoofer in the room is where it is impossible to stay - right in front of the the door, etc.
Also, in most cases, it will not remove room modes - at least not at the desirable level.

 

[olieb]

In most cases, this will be done by moving the subwoofer a little.

So here you go. This is the simulation of my room with a single sub and the resulting FR simulated in REW.
Now tell me where to put it in such a way that the room modes become bearable.
I would be grateful.

EDIT: And just for the fun of it. In this room (not square but approaching it) this is how a DBA simulates.
The difference being that this is an acoustic solution instead of a bit of EQ on the signal (that cannot change the acoustics a bit).
It is not even a contest (notice the scale).

 

[landco]

You seem to be talking about multiple subs, not a DBA. A double bass array has four or more subs on the front wall and the same on the back wall, so minimum 8 subs, all of them off the floor.

Of course, if you don't adjust the volume of these 8 subwoofers very precisely, then a blind test won't be needed one of the problems of competently organizing such tests, which everyone forgets about...

 

[Vladimir Filevski]

You seem to be talking about multiple subs, not a DBA. A double bass array has four or more subs on the front wall and the same on the back wall, so minimum 8 subs, all of them off the floor.

Old variant of DBA has 4 subwoofers. New one has 8.

 

[landco]

Now tell me where to put it in such a way that the room modes become bearable.

square room? you're out of luck

 

[Vladimir Filevski]

square room? you're out of luck

Not a problem with DBA.

Edit: see DBA fix for square room in the post #22, thanks to @olieb .

 

[Vladimir Filevski]

Of course, if you don't adjust the volume of these 8 subwoofers very precisely, then a blind test won't be needed

Of course, if you don't know how to adjust very precisely volumes of those 8 subwoofers - it is not a job for you, hire a professional... or do the blind test.

 

[Arindal]

In most cases, this will be done by moving the subwoofer a little.

Moving a subwoofer a little does not solve any problem with room modes being excited and leading to all the problems I have listed. You will still have listening positions with various dips and peaks, you will still have cancellation issues, audibly long decay and room modes being excited in a non-linear way depending on SPL and duration of the signal.

Could you please give a technical explanation how all that could be solved, solely with digital measures plus moving a single subwoofer? Seems impossible too.

 

[landco]

Moving a subwoofer a little does not solve any problem with room modes

And again, an inattentive reader of my post. There is no need to remove all the mods, it is enough to remove the gap in the listening area.

 

[OCA]

Sample DBA with just 2 subs (note the sub locations buried inside walls, delayed and inverted second sub):

Full flat response up to over 50Hz and flat group delay:

 

[olieb]

square room? you're out of luck

Well, so we made the transition from marketing to ...?
The problem is not the "square" room, but the single sub.
With a single sub you are "out of luck" all the time. DRC might help a bit with the worst problems but that is all you can get.
Here is another out of luck situation. The same room as above, I just added 2.5m for having a rectangle.
Now, where to put the sub? (Don't answer, you will not find a good acceptable place outside of room centre).

 

[Arindal]

And again, an inattentive reader of my post. There is no need to remove all the mods, it is enough to remove the gap in the listening area.

Which post of yours would be explaining how to avoid all disadvantageous consequences of room modes with one subwoofer from a technical perspective? Please link, or further elaborate on the method.

Removing the mods from this forum might have unforeseeable consequences ;-)

But if you are talking about the room modes, they do in many cases not allow an even response over several positions in the listening area. How would you solve this? And no, my sofa does not have any gaps, I still can comfortably move from one position to the other.

 

[Vladimir Filevski]

And again, an inattentive reader of my post.

And again, you are trolling, throwing away all hard science evidences (measurements too).

There is no need to remove all the mods, it is enough to remove the gap in the listening area.

Bear in mind there are professionals and experts here on this forum, please stop posting further...

 

[landco]

You will still have listening positions with various dips and peaks

What is important to us is the final frequency response of the entire system, isn't it? As you can see from the graph, there are no dips in the low-frequency region.

 

[nathan]

That is a single measurement (not just a single seat, but literally the sound of one ear). If you measure several times around the area of one seat, you will have the measurements more closely approximating one listener. Then repeat that for the other people and seats in the room.

 

[Vladimir Filevski]

As you can see from the graph, there are no dips in the low-frequency region.

?
8 dB dip at about 130 Hz is 8 dB dip and frequency of 130 Hz is in the low-frequency region.

 

[landco]

That is a single measurement (not just a single seat, but literally the sound of one ear)

This is the measurement in the listening area that corresponds to the dimensions of the chair.

 

[landco]

?
8 dB dip at about 130 Hz is 8 dB dip and frequency of 130 Hz is in the low-frequency region.

You need to take the average value, then it turns out to be around 5 dB, besides, this narrow modal dip is completely unnoticeable in real listening. That is why I said that comparative blind tests are the decisive argument "for" or "against"

 

[Vladimir Filevski]

You need to take the average value, then it turns out to be around 5 dB,

I took average value - it is 7-8 dB. And it is a dip.

besides, this narrow modal dip is completely unnoticeable in real listening.

Says who? Did you make blind listening test?
5 dB dip over one octave is very much noticeable. I suggest you to check your hearing at doctor.

That is why I said that comparative blind tests are the decisive argument "for" or "against"

Yes. Did you make comparative blind listening test?

 

[nathan]

This is the measurement in the listening area that corresponds to the dimensions of the chair.

Unless your head is in a vice and you have only one ear you need to take several measurements spaced at least a foot apart from the center of your head.

Yes it is possible in some rooms with luck to get reasonable response for a single listener.

Your measurement doesn't demonstrate that, as is. Multiple measurements are needed.

But in general: Multiple sub setups including things like DBA are for the other 95% of rooms where:

1. one doesn’t luck into a situation where a single sub can be be placed such that it provides tame-able bass for even just one seat, or
2. where there is more than one seat.

TLDR, I'm not saying you don't have great bass at your seating location.

I trust that you do and like what you hear!

I'm saying that a single measurement doesn't "prove" that you have great bass.

And, more important, in most rooms it's not possible to do a good job with a single sub. Things like multiple subs, and even sophisticated implementations of multiple subs like a DBA, are required to get consistent bass -- often for even a single listener, and "always" for multiple listeners.