I have an idea how to make the DBA array stereo: you need more subs and a dsp per sub but then you can create any wave front in all directions like this:
What do you think?
My measurements were a little delayed by a local thunderstorm. But here's more....!
Here I have added some global EQ to smoothen the overall frequency response up to 100 Hz. This measurement was also done with not smoothing.
And the decay
As we can see, the decay is short and clean from up to 100 Hz. It is however possible to get this even better by using EQ on the rear array.
Here I have added some global EQ to smoothen the overall frequency response up to 100 Hz. This measurement was also done with not smoothing.
And the decay
As we can see, the decay is short and clean from up to 100 Hz. It is however possible to get this even better by using EQ on the rear array.
With EQ on the rear array it's possible to clean up the decay even further. Here's a direct comparison with and without rear array EQ, zoomed in on the 20-100 Hz frequency range.
Let's see how this thing performs without the rear array. I've equalized the front array so the frequency response is the same as with the rear array. As we see, the two responses are closely matched.
Here's the decay of the front array only. This shows the effect of the rear array. As we see, the decay is not as clean as with the rear array, even though it's still quite good.
Here's the decay of the front array only. This shows the effect of the rear array. As we see, the decay is not as clean as with the rear array, even though it's still quite good.
It would be interesting to see how a single monopole subwoofer performs in my room compared to the DBA, right?
I disconnected all the subwoofers in the front array except for this one. And by the way - here's my array layout. The front wall is 5 meters wide, and the average ceiling height is 3 meters.
Response is EQ'ed flat from 20 to 100 Hz of course.
And here's the decay. Not quite as short and smooth as the DBA.............
I disconnected all the subwoofers in the front array except for this one. And by the way - here's my array layout. The front wall is 5 meters wide, and the average ceiling height is 3 meters.
Response is EQ'ed flat from 20 to 100 Hz of course.
And here's the decay. Not quite as short and smooth as the DBA.............
Here's two pictures of the front end of my room, with the 3 meter wide projection screen and drapes removed. They've been taken with a wide-angle lens, so the perspective is a bit weird.
We see the twelve subwoofers in the front DBA array, as well as my center channel based on a Magnepan 3.6 with two dipole 4x10" midbass panels on each side. You also see the front speakers based on Magnepan 3.7 with dipole 4x12" midbass panels.
We see the twelve subwoofers in the front DBA array, as well as my center channel based on a Magnepan 3.6 with two dipole 4x10" midbass panels on each side. You also see the front speakers based on Magnepan 3.7 with dipole 4x12" midbass panels.
Rear array with the drapes usually covering it removed. Also showing surround speakers equal to the front speakers and hush-box for a projector.
The arrays are powered by three ICEpower 2000AS2 2-channel amplifiers. The front array has two of these amps since it is higher in level than the rear, thus it needs more power. All EQ, delay and level is adjusted in a MiniDSP flex. I will go into detail about this later. My Anthem AVM 70 preamp/processor takes care of the crossovers and bass management. All speakers are crossed over to the DBA at 80 Hz.
I don’t think this can create a plane wave?
I do have a stereo DBA idea - install two separate arrays on the side walls.
That being said, our hearing is not considered to be able to locate where low frequencies are coming from, so
I don’t think it’s any point to do it anyway.
That would also be feasible, you can then do this with one DBA and mix the L and R signals in the right way.
And yes with a phased array you can create wave fronts in any direction..
Here's how this DBA has been set up in the MiniDSP Flex.
You may wonder why I'm using an analog loopback instead of just routing In 1 directly to Out 1 and 2. There are two reasons - the number of available PEQs is doubled. I also wanted to run a FIR phase correction filter. The MiniDSP Flex can only do that on outputs. If not using a loopback, the FIR must had been applied at two outputs (out 1 and 2).... using just one is simpler. I'm lazy...
I use EQ that is affecting both arrays in two places since I ran out of available PEQs. That is on the In 1 (SUBW in), and the Out 4 (Loopback out). The front array has no dedicated EQ, but the rear has a little to shorten the decay of a few room modes.
In 1 (SUBW in)
PEQ
Out 4 (Loopback out)
PEQ
Out 2 (Rear array)
PEQ - these PEQs are used to shorten the decay of specific room modes. They are all 1 dB or less, but their effect is quite obvious.
You may wonder why I'm using an analog loopback instead of just routing In 1 directly to Out 1 and 2. There are two reasons - the number of available PEQs is doubled. I also wanted to run a FIR phase correction filter. The MiniDSP Flex can only do that on outputs. If not using a loopback, the FIR must had been applied at two outputs (out 1 and 2).... using just one is simpler. I'm lazy...
I use EQ that is affecting both arrays in two places since I ran out of available PEQs. That is on the In 1 (SUBW in), and the Out 4 (Loopback out). The front array has no dedicated EQ, but the rear has a little to shorten the decay of a few room modes.
In 1 (SUBW in)
PEQ
Out 4 (Loopback out)
PEQ
Out 2 (Rear array)
PEQ - these PEQs are used to shorten the decay of specific room modes. They are all 1 dB or less, but their effect is quite obvious.
And here's the parameters of the FIR phase correction filter in rePhase.
It corrects for the low end rolloff of the DBA itself, and the bass management crossover in my AV processor.
It corrects for the low end rolloff of the DBA itself, and the bass management crossover in my AV processor.
Hard to imagine this in anything other than a purpose built room. I wonder when the point of diminishing returns is reached? 8 subs? 12? 20? For most this is an academic exercise with no possibility of ever installing such a system but bravo for the over the top effort!
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When people ask me "how can I get bass as good as this in my home which is an odd shaped large open space?" I answer - "headphones" ... 😏
To create a double bass array, at least eight subwoofers is required - 2 x 2 on each opposing wall. I could have done it with an array of 2x3 on each wall, and still get good response up to my crossover point at 80 Hz.
I had collected a lot of SEAS L26ROY woofers of the years used for various projects, and decided to use eighteen of them for my first DBA, with a 3x3 array on each wall. I increased that to twenty-four some time later.
The SEAS L26ROY is an expensive driver, so If I was to build the whole thing from scratch today, I would have looked at something else I guess.
To create a double bass array, at least eight subwoofers is required - 2 x 2 on each opposing wall. I could have done it with an array of 2x3 on each wall, and still get good response up to my crossover point at 80 Hz.
I had collected a lot of SEAS L26ROY woofers of the years used for various projects, and decided to use eighteen of them for my first DBA, with a 3x3 array on each wall. I increased that to twenty-four some time later.
The SEAS L26ROY is an expensive driver, so If I was to build the whole thing from scratch today, I would have looked at something else I guess.
Quad bass array?😀
Stereo speaker setup in a corner works fine:
Just put two DBA in same room, one for each dimension. But how many subs would that be? It's likely cheaper to make new room with 2m bass absorption on all walls?😀
A typical scenario is when you have 2 x 2 on the front and back wall in a room with risers and 2 or 3 rows of seats. The back is not an exact mirror of the front and the planar wave is obstructed by risers and seats. Has anyone tried this?
I suppose for a DBA setup to be be effective in terms of power and dynamics, one would need subs with a bit of muscle due to the half space gain.
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