Best Way four Bass Array

@audiokinesis   Sounds fascinating, I'd like to hear about those radiation patterns...

I've been playing about the idea of a 'low rent' DIY DBA mated to a Walsh array, simply since it makes sense to me....*S*

Geek away.... ;)

@avsjerry wrote: "Sounds fascinating, I’d like to hear about those radiation patterns... Geek away.... ;)"

Okay, first a bit of background:

In the playback room there is a competition between two sets of ambience cues: The venue spatial cues on the recording (whether they be real or engineered or both), and the “small room signature” cues inherent to the playback room. The ear will tend to accept whichever “package” of cues is the most plausible. What we want to do is, minimize the “small room signature” cues while maximizing the venue spatial cues on the recording, such that the latter become perceptually dominant, enabling a “you are there” presentation (given a good recording).

The first in-room reflections are the strongest conveyors of the playback room’s “small room signature” cues, and the reverberation tails on the recording are the strongest conveyors of the venue spatial cues on the recording. We can think of the in-room reflections as “carriers” for the reverberation tails on the recording, which ideally should arrive from all around.

Thus we want to minimize and/or disrupt the early reflections, as these are what indicate the dimensions of the playback room. Then we want plenty of spectrally-correct, relatively late-arriving reflections, arriving from many directions, and thereby delivering the reverberation tails on the recording from many directions. The ear/brain system recognizes these reverberation tails by their harmonic structures, so we want the overtones in the reflections to be intact. If the late-arriving reflections have their upper harmonics removed by in-room absorption they will no longer be identifiable as “signal” and will become “noise”, so for this approach we don’t want to rely on absorptive room treatments.

The radiation pattern I use to do this has two parts: First, the forward-firing pattern is narrow enough that it “misses” the same-side wall when the speakers are strongly toed-in (they are designed to be toed-in about 45 degrees). So the first significant sidewall reflection for the left speaker is the long, across-the-room bounce off the right-side wall, and vice-versa. Therefore the arrival times of the most significant first reflections are much later than would have normally been the case in that size room, which weakens and disrupts the “small room signature” of the playback room, setting the stage for the recording venue package of cues on the recording to dominate.

The second part of the radiation pattern is aimed up-and-back at a 45-degree angle, such that it bounces off the wall behind the speakers and then off the ceiling before arriving at the listening position. The resulting path-length-induced delay prevents these reflections from contributing detrimental early-onset “small room signature” cues, so their contribution becomes beneficial late-arriving reflections which arrive from many directions (remember the speakers are toed-in so the rear-firing patterns are correspondingly toed-out). The reverberation tails on the recordings are thereby effectively presented.

Not that this is the only way to minimize small-room-signature while effectively presenting the venue spatial cues on the recording, but it is less demanding of listening room size and/or professional-grade acoustic treatment, and generally more forgiving of listener locations, than other approaches.

In my opinion.

Duke

Mij,

Will you share your bass solutions?

@audiokinesis Hi Duke! Always great to read and learn from your postings!

I am also interested in your satellite speaker. Where does it crossover?

@jeffseight I have been thoroughly enjoying my DBA from Audiokinesis in 5 different rooms (the smallest and first listening room was 9’ x 11’ minus closets) varying in size, shape, furnishings, and floorings.

I have tried many subwoofers but nothing worked in the tiny room. I gave up trying until hearing about the DBA concept. After doing my research, decided to try. Duke was very upfront and honest when he said that is the smallest room so far in his experience. No guarantees

The DBA worked out very well for me in the tiny room, with my system.

It is not necessary to have "matching" subwoofers.

I have not tried mixing in active subwoofers but many here have tried with great results.

I have tried mixing in/adding additional passive subwoofers. Each additional subwoofer brings a significant improvement until around the 4th or 5th one. Perhaps around 7 in a really big room.

Good news is you can start small. Just grab a decent subwoofer amplifier and a few subwoofers.

After moving twice, I am now enjoying my DBA in the 5th room since using it.

I found my DBA solution.

Hope you find yours!

@hleeid wrote:

"I am also interested in your satellite speaker. Where does it crossover?"

The satellite speaker rolls off south of 60-70 Hz or so, depending on how close it is to the wall and how many ports are open. No protective highpass filter needed unless you plan to go louder than 116 dB at 1 meter.

The satellite has two 12" midwoofers with a horn between them, so "MHM" format, then it has an up-and-back-facing horn on the back of the cabinet with its own level and spectral balance controls. The crossover between the front horn and midwoofers is about 700 Hz. The rear horn goes a bit lower.

Duke