Best Way four Bass Array

Audiokinesis Swarm is the standard.  Look them up. 

Quite Familiar. 

Still looking.

Still trying to understand the insistence on passive with a single amp. Nothing I've read about the DBA concept insists on passive subs; it's merely one way there.

What about four multi-adjustable SVS SB-2000 subs. 12" and 500 watts and adjustable individually for each sub. The problem is?  (not money $2000-$2400)

Sorry for the 'pollution'. Not sure how many answers there are unless homemade systems should apply?  Or four Dayton audio boxes and one amp? That'd work.

@jeffseight wote: "I have heard DBA, Distributed Bass Arrays in two home systems that both qualify as "Best Home Sound" I have heard. I have not been in every high end home system but I have experienced some pretty good ones.

Here is the outline of what I consider as key features:

1. Four Passive 8" subwoofers.

2. Powered by a separate 500+watt amp.

3. Must have fully adjustable phase control. 0-180 won’t do.

4. Sealed boxes for a fast, tight sound.

5. Down firing preferred.

I want this to be a $3-4k adventure. Buying used is best."

Well it’s probably no surprise that I like the direction you’re exploring!

@soix wrote: "Audiokinesis Swarm is the standard."

Thanks for the mention!

I am not aware of any 8-inch passive subs that fit @jeffseight’s criteria. I have designed an 8" version of the Swarm but the cost difference between it and my 10" version would be minor, as the same number of sheets of material is required, and the same amount of labor is required, and nearly the same cost in packing materials is required, so the manufacturing cost savings comes down to the difference in woofer cost.

Any passive sub + external subwoofer amplification with 180 degrees of variable phase control will give you 360 degrees of phase adjustability because you can reverse the polarity of the speaker wires. So if you want 270 degrees, here’s how you get there: 180 degrees from reversing wire polarity + 90 degrees from the amplifier’s phase control = 270 degrees.

I hope you don’t mind if I go into some detail about my design choices, as my product was mentioned and some of my choices are a bit counter-intuitive given that we both prioritize "tight, fast sound." In general, sealed box sub + room interaction = "tighter and faster" bass than a comparable vented-box sub, because in general a sealed box’s inherent response is more room-gain-friendly.

The in-room frequency response is the best predictor of perceived bass quality. At low frequencies, speakers + room = a "minimum phase system", which means that the time-domain response tracks the frequency response. So when we have fixed the in-room frequency response we have simultaneously fixed the in-room time-domain response, and vice-versa. When we have boomy bass response it is because of frequency response peaking in the bass region, and it takes longer for the energy in that region to decay into inaudibility, so it sounds (and IS!) "slow". (That being said, note that, according to Dr. Floyd Toole, what the ear actually detects is the frequency response peak rather than the time-domain "ringing" that accompanies the peak.)

Many if not most vented-box subs are optimized for deepest loudest bass, and when typical boundary reinforcement is added to their native frequency response, the result tends to be too much low-end energy, which is made even more audible and objectionable by the room-induced frequency response peaks. In contrast a good low-Q sealed box sub starts rolling off higher but does so much more gently, and the net result of a sealed sub’s inherent roll-off plus boundary reinforcement tends to not result in bass region peaks that stick out like sore thumbs, at least not nearly as bad as a typical vented box sub.

The inherent frequency response of a Swarm sub with the port open is the approximate inverse of "typical" room gain, falling off at 3 dB per octave across the bass region, and accelerating rapidly south of 18 Hz or so. I call this "room gain compensation tuning", for obvious reasons. Even the lowest-Q sealed boxes do not have a 3 dB per octave inherent rolloff across the bass region, at least not without EQ. If this tuning results in too much bass energy (some rooms have more boundary reinforcement than others), the port(s) can be plugged on one or more of the Swarm units.

It is possible to design a vented box whose group delay exceeds the ear’s detection threshold, and it is also possible to design a vented box whose group delay is well below the ear’s detection threshold. It just so happens that "room gain compensation tuning" results in unusually low group delay for a vented box, well below the ear’s experimentally-determined detection threshold (which varies with frequency). To give context, the excess decay times of in-room bass peaks are typically several times greater than the ear’s group delay detection threshold.

So while I agree that in general sealed-box subs have "tighter and faster" in-room bass than comparable vented box subs, I think the design specifics of the Swarm units make them exceptions to this rule. 

Imo there are three other advantages of using "room gain compensation tuned" vented boxes. First, approximately four times as much power would be required to equalize a sealed box to be "flat" in-room down to the same frequency, because we get 6 dB of gain at the port tuning frequency relative to a sealed box. This makes life easier on the driver (far less voice coil heating and far less excursion required), and on the amplifier (roughly four times as much power would be needed down around the port tuning frequency for a comparable equalized sealed box).

Second, our "starting point" in-room response probably won’t need a great deal of EQ to end up where we want it, especially if we take advantage of the adjustability offered by being able to plug ports (turning the enclosure into a low-Q sealed box) and reverse polarity of the individual Swarm units.

Third, even for equal power input, a vented box has an advantage over a sealed box from a thermal power handling standpoint, because air movement in the port results in an exchange of air with the outside world. With a sealed box, there is no exchange of air with the outside world and so it continues to heat up, possibly resulting in greater thermal compression and/or shortened driver life.

Regarding whether the woofer is down-firing or not, imo good performance can be had either way. I went with rear-firing for the Swarm because I needed to shoe-horn a fairly long port into a fairly small box, so the port runs north-south in a rather tall-and-skinny enclosure, with the port’s outer flare occupying the space on the bottom of the box that the woofer would have required.

A used Swarm would not exceed the $3-$4k price range mentioned, but a new Swarm would (as my costs have gone up a LOT over the past year or so.)

@jeffseight you might end up having to build your own, or having a local woodworker build the enclosures for you, in order to meet your criteria. You might want to consider using 10" drivers as there tends to be a significant step up in motor strength going from a high-end 8" subwoofer to a high-end 10" subwoofer, and in my experience there is a correlation between motor strength and perceived impact. Also given that EQ is likely to be needed to get bottom-octave bass in-room from a sealed 8" or 10" sub, the higher power handling of the larger 10" motor makes EQ less likely to thermally and/or mechanically stress the woofer.

The amplifier I use (and recommend you consider) is the Dayton Audio SA-1000, Parts Express part number 300-811, as I have yet to find its equivalent for anywhere near the price. It has almost all of the features I want (a speaker-level input would have been nice to have, but an external voltage divider network can be purchased or made).

Best of luck with your quest!

Duke

Duke,

That contribution is very appreciated, thanks. 

It took me a while to understand that "Bass Counts"

With female vocals as my first love I was too focused on 

midrange performance. 

 

I congratulate you for providing a truly needed product. Other

sub makers don't get it. Even the REL CS  folks recently wrongly explained

the function of footers (GAIA or Wedges) value for vibration control. 

 

One reason for the 8" choice is that my current REL seems 

fairly adequate. So x 4 would seem be enough for my midsized room.

The other is with 4 boxes I think the smaller to better or they impose

a lot on the room. When you have 4 boxes to place, smaller is better.

 

I'm past listening at anything over 75dBs so I won't be pushing the 8" that much.

 

That said if a 10" costs about the same and doesn't make the box

bigger by much I am good with that too. 

 

Down firing for me is a peace of mind choice. Better protection from life, dogs etc.

Thanks for the tip on the Dayton Amp. 

What new products do you have in work?

 

 

 

@jeffseight 

I have been using a bass array for around two years and couldn't be happier.

I use 4 subs. Two Rel T5's, one Rel T7 and one SVS SB2000. They are controlled by a MiniDSP 2x4, which is fed from the pre out of my integrated.

Everything was purchased used except for the MiniDSP, so the cost was around $1,800 CDN.

@jeffseight wrote:  "What new products do you have in work?"

I'm working on a "satellite" speaker intended to be used with subwooofers.  The emphasis is on room interaction characteristics which effectively present the venue cues on the recording, the intention being to enable a "you are there" presentation in a fairly normal playback room with a good recording.  So the radiation pattern is a bit unorthodox. 

Details if you're up for some geekspeak.

Duke

@jeffseight , you have not heard anything yet. Keep listening and enjoy the journey.

@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