Mijostyn, just totally dead wrong yet again: Come on clio you can be more honest than that! Cable risers are for people who want to show off their silly $10,000 speaker wires. Anything they do to the sound is purely psychological.
Chris Brady, of Teres Audio, was over one night. At one point while a song was playing I walked across the room removing the Cable Elevators one by one until the speaker cables were laying on the floor. Then while the same track was still playing, put them all back. Soon as the track was over Chris said he heard the sound stage collapse and come back as the Elevators were removed and replaced. This being some time before mijostyn came along I didn't know to tell Chris it was all in his head. Because I know so well how speaker cables, interconnects and power cords benefit from being up off the floor I was really skeptical when Duke told me not only that it doesn't matter with subs, but to save your money on cables because ordinary wire works just fine too. Sure enough, right again. |
Hello Hans, Remember, connecting the 4 DEBRA subs is a bit different from hooking up regular speakers with regular spkr wire that has a pos. conductor wire and a neg.conductor wire combined side by side. With the Debra, you need to follow the procedure listed below: The DEBRA’s supplied sub amp/control unit has dual speaker output terminals, labelled as A and B, and this thread details how the final sub cabling hookups are done in a series/parallel method: Attach a single wire from the amp’s speaker A’s pos. output terminal to Sub#1’s pos. input terminal. Attach a single wire from the amp’s speaker A’s neg. output terminal to Sub#2’s neg. input terminal. Attach a single wire from Sub#1’s neg. input terminal to Sub#2’s pos. input terminal. Attach Sub 3 & 4 using this series/parallel method on the amp’s speaker B’s output terminals.
"So after deciding on a cable management solution, should the rule of thumb be to determine the longest run of cable (to reach the farthest subwoofer) and use that length for the remaining three?"
"Am I assuming correctly that if multiple subwoofers are used, their cable lengths should be identical, as with the main speakers?"
Answers: Connections are made using single conductor wire which is a bit different than regular speaker wire. To hookup the first pair of subs requires 3 single conductor wires: 1 wire is connected from the amp’s A pos.output to sub#1’s pos. terminal input, a second wire is connected from the amp’s A neg. output to sub#2’s neg. terminal input and a third wire is connected from sub#1’s negative terminal to sub#2’s pos. terminal. The proper length of each of these wires will depend on the distances between the amp and sub#1 and sub#2 as well as the distance between sub#1 and sub#2. You will not know these distances until you determine exactly where the amp will be placed in your office and exactly where sub#1 and sub#2 sound the best in your room. The 2nd pair of subs also require 3 single conductor wires for hookup and you’ll need to determine exactly where sub#3 and sub#4 sound best in your room before the proper length of these 3 wires can be determined. I suggest you measure your room, decide where the DEBRA’s amp is going to be placed and then calll James Monteyn at Audio Kinesis in Utah to order your DEBRA and the 6 cables you’ll need for hookup. James will help you determine the length of each sub cable (with a bit extra added to allow for a margin of error in measurement accuracy) as well as the interconnects between your amp and the DEBRA amp and make them all for you at a very reasonable price. I actually forgot exactly how we did this but I know James will walk you through the process and he may ask you additional questions and measurements. I think I just initially told him my room dimensions, where in the room the amp would be located and how I was going to route the 6 hookup cables and he did the rest. The cables will arrive with the subs and amp, so you’ll just need to route the cables, cut and strip the wire on one end of some of the cables to the proper length and make the connections. I’ll also help you through the whole process through installation, configuration and completion.
"What is the reason for the (temporary?) positioning of Sub#1 and #2 facing the ceiling? Not sure I understand how/why this helps to determine woofer placement."
This is called "the Crawl Method" and it’s just a proven effective process or ’useful trick’ for properly positioning each of the 4 subs in your room. This is the exact same method I used to locate my 4 subs and it was fairly convenient and works extremely well. You’ll just be sequentially and temporarily placing each sub #1 -#4, with each sub driver facing temporarily upward to let the bass soundwaves be launched into the room freely, so you can clearly hear it and determine exactly where the bass sounds best to you as you crawl on your hands and knees in a counter-clockwise direction around the perimeter of your room beginning at the front right corner of your room. Once you determine the exact spot that sub#1 sounds best, you then screw in the set of three spiked footers into the sub’s bottom and reposition sub#1 upright to this spot with the 10" driver facing, and about 1-2 inches away from, the wall. You then place sub#2 (with sub#1 continuing to play) face up at your listening position and continue to crawl around the perimeter of your room, beginning at sub#1, in a counter-clockwise direction until you discover the next exact spot the bass sounds best. Once you determine the exact spot that sub#2sounds best, you then screw in the set of three spiked footers into the sub’s bottom and reposition sub#2 upright to this spot with the 10" driver facing, and about 1-2 inches away from, the wall. This completes the ideal and permanent positioning of your front pair of subs connected to the "A" labelled left + right speaker outputs on the sub amp/controller. The next steps are to repeat this procedure to properly position sub#3 and #4 that are connected to the "B" labelled left + right speaker outputs on the sub amp/controller. Once all 4 subs have been properly positioned and playing, sit at your desk listening seat and verify that the bass sounds exceptionally good to you. Also walk around your office and verify the bass sounds equally good to you throughout your entire office. If it does, you’ve successfully positioned all 4 subs and this stage is completed. If it doesn’t, you’ll need to repeat this procedure from the beginning. The lesson being to take your time and be precise in determining the spot the bass sounds best to you so that each sub is properly positioned. The next to final step is to disconnect each sub’s cabling, reroute the cables so that they’re concealed optimally and then reconnect them. Once all cables are optimally concealed, routed and reconnected, the final step is to play the music of your choice and enjoy the heck out of your system with the newly installed near state of the art bass system!
Enjoy, Tim |
Clio09 wrote: "I don't run equal lengths of cables to any of my woofers. Instead I cut
to the length required for each woofer. I also don't worry about
stepping on the cables while they are under the carpet."
Same here.
Duke
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Well there is the display factor to consider with risers, but I always picture someone tripping over the elevated wire, yanking the connections from components or speakers, or worse yet dragging a component off the rack or a speaker off a stand.
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Come on clio you can be more honest than that! Cable risers are for people who want to show off their silly $10,000 speaker wires. Anything they do to the sound is purely psychological.
Hleeid, just buy a role of the thickest gauge you need and use it on all four speakers. Like clio I make all my wires to fit. |
I don't run equal lengths of cables to any of my woofers. Instead I cut to the length required for each woofer. I also don't worry about stepping on the cables while they are under the carpet. Do your own testing with cable risers, etc. I don't find that they make a difference.
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Ok. This is very helpful (and much appreciated!)! So after deciding on a cable management solution, should the rule of thumb be to determine the longest run of cable (to reach the farthest subwoofer) and use that length for the remaining three? Am I assuming correctly that if multiple subwoofers are used, their cable lengths should be identical, as with the main speakers? Duke - You mentioned cables can be run under rugs. I noticed some discussion on using suspenders under speaker cables to keep them off the floor. Is this just a myth? If so, should I avoid stepping on or placing anything heavy on the carpet directly covering the cable? You also mentioned placing a subwoofer on its side. Is there a corresponding spike/pad configuration for the subwoofer placed sideways? Tim - In the thread you provided the link for: https://forum.audiogon.com/discussions/anyone-else-using-an-audio-kinesis-swarm-or-debra-distributed... Sub#1 is hooked up and placed on its back (driver facing the ceiling) at the normal listening position. Music is played that has good and repetitive bass. Sub#2 is hooked up and placed on its back at the primary listening position. With sub 1 & 2 playing, continue walking around the edges of your room and determine again where the bass sounds best to you.
What is the reason for the (temporary?) positioning of Sub#1 and #2 facing the ceiling? Not sure I understand how/why this helps to determine woofer placement. Thanks, Hans |
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"So for those of you enjoying your DBA systems, any suggestions on creative speaker cable management?"
You can use 16 gauge zip cord, make the wires as long as necessary to hug the walls if that helps, and you can run ’em under rugs.
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I use 16 AWG zip cord for my cables. I run them along the walls and under the carpet (8 x 10 Persian rug) to keep them out of the way. Works just fine for me.
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Hello Hans, I'm glad you went out and listened to subs at local shops in your area. It's a very good method of gaining knowledge and experience, getting an idea of costs, an understanding of sound quality performance differences between sub brands and sizes as well as determining what you like. The truth is that a pair of good quality subs, properly positioned and configured, would provide very good bass performance in your office at a single designated listening position such as your desk chair behind your desk. You could also save some money by buying a pair of good quality subs online with a free 30-day in-office trial period. The main advantages of using the Audio Kinesis DEBRA 4-sub DBA system are that the bass will not only be even faster, smoother, more detailed, more powerful, more effortless, with better dynamics and more natural sounding overall than a pair of good subs but it will also sound like this throughout your entire office, not just at your desk chair. Duke has often stated something like: "2 subs will sound twice as good as 1 sub, 4 subs will sound twice as good as 2 and 8 subs will sound like good grounds for divorce to a lawyer." The 4-sub DEBRA does cost more than many pairs of subs would at $2,800 and requires a bit of a leap of faith to even try but it'll perform better and the risk is mitigated by James and Duke offering a free in-home trial period. Of course, it's completely your decision whether you're satisfied with very good bass response at your desk for a reasonable price with a pair of good quality subs or you're willing to spend a few hundred dollars more and achieve exceptionally good bass response throughout your entire room by using the 4-sub DEBRA. I'm fairly certain both options would provide bass that blends very well with your main speakers. Most of your questions/concerns you posted about wiring and cables are addressed on the thread I started awhile ago on the DEBRA system linked below. https://forum.audiogon.com/discussions/anyone-else-using-an-audio-kinesis-swarm-or-debra-distributed... The DEBRA's supplied sub amp/control unit has dual speaker output terminals, labelled as A and B, and this thread details how the final sub cabling hookups are done in a series/parallel method: Attach a single wire from the amp’s speaker A’s pos. output terminal to Sub#1’s pos. input terminal. Attach a single wire from the amp’s speaker A’s neg. output terminal to Sub#2’s neg. input terminal. Attach a single wire from Sub#1’s neg. input terminal to Sub#2’s pos. input terminal. Attach Sub 3 & 4 using this series/parallel method on the amp’s speaker B’s output terminals. I planned out all the wire lengths (with a small margin of error inches added to each) and ordered single, high quality and low gauge speaker wire along with the sub system for a very reasonable price from AK's James Romeyn in Utah. Once the ideal locations for the subs was determined, I drilled holes in my room’s carpeting and subflooring to the crawl space below, and was able to hide all of the connecting wires. Each sub comes with a set of 3 brass spiked footers for positioning on carpeted floors. These raise each sub about a half inch off the floor which allows the clearance for the running of speaker wires to each sub's input terminals located on their bottoms. If you don't have a crawl space or basement located below your office to run and hide the wires, there are other options for doing so such as running them behind baseboards, inside the walls or through a drop down ceiling or an attic. Another idea is to run the wires in a plastic conduit that could be attached to the top of your baseboards in a matching color so that it appears to be a part of the baseboards. You could probably do it yourself but it may be easier and less frustrating just to hire an electrician to do it. I'd suggest avoiding running them underneath wall to wall carpeting mainly because it seems too permanent to me and you may have future ease of access issues to the wiring.
Later, Tim |
Ok. After reading through these postings and researching the many resources kindly provided here, I am still a newbie but at least not a complete newbie!
The absolute best advice I got from this forum was to just go and listen to whatever you are considering.
I went to the local shops and demoed subwoofers in single and pairs (unfortunately no shop in the Boston area had a Swarm or DEBRA system set up).
In the many different sized and shaped listening rooms (and after extreme sticker shock learning how much things actually cost in these rooms!),not only did I hear the difference between single vs. paired(?) subwoofers, but actually started to better understand the more technical writings on subwoofers.
So after about an hour making the poor sales persons nervous while I kept getting up and moving one woofer here, the other there, sitting down and listening, getting up, moving subwoofers again,...the DBA system now makes sense to me on many more levels.
Tim - I really appreciate your staying the course with this thread! Definitely learned a lot!
So for those of you enjoying your DBA systems, any suggestions on creative speaker cable management?
Looking around my office room, I can't imagine how to route the additional cables without making a big trip hazard out of the room.
Should cables be as short as possible yet still reach? Or can long cables be used to route along the walls?
Should cables not be placed under carpets?
Floor suspenders for cables?
Thanks,
Hans
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Hello allucard and bdp24,
I don't doubt that both the REL HT1205 and Rhythmik L12 are very good subs that work vey well in your systems. There are also other very good subs currently available that run the gambit from relative bargains to quite expensive.
However, the OP Hans has expressed an interest in considering the 4-sub Audio Kinesis DEBRA bass system with the four subs positioned around the perimeter of his office in a distributed bass array (DBA) arrangement. The 4-sub DBA concept is a new one to Hans and many others, which is why many of the recent posts on this thread have concerned the concept's explanation, its effectiveness and possible further refinements.
In the spirit of educating others on the DBA concept, both of you mentioning alternative very good reasonably priced subs that Hans could consider using raises a very good point and relates to other important advantages of using the 4-sub DBA concept: its flexibility and scalability. I believe anyone considering a DBA system should be aware of these for best results.
Its flexibility is demonstrated by the fact that effective custom DBA systems can be created using any subs an individual prefers. Its scalability is demonstrated by the fact that the actual in-room maximum bass power, impact and dynamics can be increased and decreased according to the subs utilized as well as adjusted by the setting of the volume and crossover frequency controls.
The essential main requirements for an effective DBA system are that four subs be used and that they're properly positioned in the room. There is a vendor offering an effective DBA system utilizing only three subs but it requires professional positioning of the subs based on a proprietary computer program.
The acceptable actual subs utilized in an effective custom DBA are less restrictive and can range from using small DIY subs containing 8" drivers, like clio09 uses, to using the largest and most expensive subs available.
I also wanted to make sure Hans understands the practical distinctions between installing and configuring a 4-sub custom DBA system versus a complete kit DBA system like the AK SWARM or DEBRA systems. The main method of seamlessly integrating a sub or subs into one's system are the proper setting of the Volume, Crossover Frequency and Phase controls.
With a custom DBA system, using traditional self-amplified subs, all three of these settings are required to be set individually on each of the four subs. With a complete kit SWARM or DEBRA DBA system, using passive subs amplified by a separate external amp/control unit, all three of these settings are only required to be set once for all four subs as a group on the amp/control unit.
Another option, if you're handy and up for it, is to buy the same sub amp/control unit the SWARM and DEBRA kits use and build four passive subs of your choice. This would allow the setting of controls once for all four subs but it could be either more or less expensive than the cost of the SWARM or DEBRA complete system, depending on the exact sub components chosen and the dollar value you designate for your own labor.
Tim
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A quad of Rythmik L12 subs can be had for about $2,000. Each will have it's own power amp and controls. |
you might also want to try the REL HT1205, I just picked up a pair of them and they are a very fast and detailed sub, don't let the HT scare you they are great for stereo set ups which is what I use them for, I use a pair of HSU VTF-3 MK5 HP subs for my HT set up. At $599.00 each the REL HT1205's are a great sub with a 500watt amp built in, Also REL only make subs.
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Tim,
It all depends on the size of the room. A smaller room does not require as much driver and in this day and age anything can be equalized given enough power.
Duke, I still really like the cylinder idea.
Mike |
" My main concern is to what degree would the extremely good bass power, impact and dynamics qualities of the four separate subs configuration used by the SWARM and DEBRA systems would be compromised when two subs are incorporated into the main speakers or smaller bass drivers are utilized. "
James and I have done a couple of audio shows with systems that incorporate two of the four subs into speaker stands, which is conceptually similar. One such room was where an industry veteran cable manufacturer said our room did the best job on his reference Fanfare for the Common Man recording of any room he had heard at any audio show, and in particular he said the tympani sounded like what he hears at the concert hall.
So I won’t claim zero compromise, but I don’t think there’s very much.
Duke
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Hello mijostyn/Mike,
You’re going to hate this, but I agree with you that most wives don’t like tripping over subs in big boxes/cabinets and are generally more concerned with aesthetics than their husbands. We men generally seem to have more utilitarian and porcine natures.
My wife is no exception and we both actually appreciate good aesthetics in our home décor; no feminine or interior decorator jokes at my expense, please. We were both pleasantly surprised on how stylish the DEBRA subs are and how well the four subs blended so well with our living room decor. I suspect the SWARM subs are equally attractive since, once the DEBRA and SWARM subs are properly installed with the speaker wire connections on the slightly elevated bottoms and with the drivers facing the nearest wall, they look like attractive wooden pedestals that are typically found in fine stores, art galleries and museums to display objects.
My wife usually has a vase of fresh flowers on one or both of the two subs that are visible toward the rear of our living room. The front two subs along the front wall, are each hidden from view behind a 6’ x 2’ Magnepan speaker panel.
Overall, both our good aesthetics and very good bass sound quality performance requirements have been completely met by the DEBRA 4-sub DBA system in our more medium sized 16’ x 23’ sized living room.
I believe that either the DEBRA or SWARM 4-sub DBA systems would meet or exceed most individuals’ expectations in any room that can accommodate the four relatively small (approximately 1’ x1’ x 2’) subs. If anybody has such a small room that they have concerns about fitting the four subs, however, it sounds like Duke’s in development system incorporating two of the four subs into the main speakers, seems like a clever alternative solution to satisfy a likely niche market.
My main concern is to what degree would the extremely good bass power, impact and dynamics qualities of the four separate subs configuration used by the SWARM and DEBRA systems would be compromised when two subs are incorporated into the main speakers or smaller bass drivers are utilized.
My main point being that I suggest that the OP, Hans, utilize the DEBRA or SWARM if he thinks the four subs can be accommodated in his small office before considering waiting for Duke’s new more integrated product to become available. My reasoning is that I’m fairly certain the bass performance will be excellent with both separate 4-sub AK DBA systems, he can continue to use his Ologe 5 main speakers that he seems to enjoy and I know the combination will blend very well with these main speakers.
I believe he’ll be thrilled with the in-room bass performance and seamless integration with his Ologe 5 main speakers or any other main speakers he may choose to utilize in the future, using either the DEBRA or DEBRA bass systems. The main concern seems to be whether the four subs can be positioned in an unobtrusive manner in his office. Based on my experience, I think he’ll be pleasantly surprised how stylish and unobtrusive either solution would actually be.
Tim
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"...the market for smallish subs might be higher than you suspect."
I’m not saying I’ll never go there, but it has to be something that I believe offers worthwhile improvement over its competition, rather than just being four small subs sold as a package.
For instance, the most obvious feature of the Swarm is, it’s four small subs sold as a package. But when we get into the performance specifics, imo the individual units are competitive with their ballpark price equivalents.
Duke
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I hear you Duke but the market for smallish subs might be higher than you suspect. Most people do not have large rooms and wife do not like tripping over big boxes. I would not charge much less for them, whatever the difference in materials is. Four 8" drivers equalized and running in a smaller room should do just fine for many of us. The other way perhaps to deal with the aesthetics are to make them look like something other than a box. What about a cylinder, driver in the bottom slot loaded into the room? |
I've been using 4 small enclosures with 8" drivers in my room for a while. The low pass is EQed to 30 Hz, but not digitally. The concept came from the old Beveridge 2SW and it's RM-3 active crossover. Today I just built the first of 4 boxes with a 10" woofer where the low pass will be EQed to 24 Hz. The external dimensions of the enclosure are 14 x 14 x 7.5 (internally .542 cu. ft.). So not such a big footprint. I currently use a method of placement for the subs recommended mijostyn as he and I have Acoustats and this method works quite well with these speakers. I have used the distributed array placement as well. IMO both methods are very useful.
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"Duke, I think what people are concerned with is the size of the subs in a small room."
That makes sense, but I don’t think I can offer a practical solution.
You see, in part because I’m a small company, my costs don’t scale down proportionate with enclosure size. So as I start shrinking the boxes I start to become less competitive with four small off-the-shelf subs.
Duke
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Duke, I think what people are concerned with is the size of the subs in a small room. I'm sure you know all this already but using a smaller enclosure with the appropriate driver then digitally equalizing it may suit people with smaller rooms....as long as you have the power to do it. It is just like treating the room as a Honda Hatch Back:) Might be a good product for you. |
"It seems like your new system concept will probably work well not only in a variety of small rooms, but also some medium sized rooms."
The main speaker array has a lot more dynamic range than one is likely to use in a small room, so yeah the system should work well in a medium-sized room too. Virtually everything in speaker design being a juggling of tradeoffs, I did make a few in favor of small room optimization.
"Does it matter if the woofer is layed down horizontally on the floor?"
Nope! I have several customers who use at least one Swarm unit on its side, sometimes on the floor, sometimes atop a book case.
"Leaning towards the DEBRA system since the (flatter?) profile woofers would probably take up less floor space."
Sounds good to me! (For the record, I don’t get a "kickback" on Debra sales.)
"Duke - are you building (or have built) a new sub array system for smaller rooms?"
Not yet, but shoot me a message or an e-mail if you’d like to exchange ramblings about tradeoffs.
Duke
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Ok, hearing about Duke arranging each main speaker with a sub solves the majority of my small room size issues.
Does it matter if the woofer is layed down horizontally on the floor?
If not, a horizontally situated woofer would fit under my
floor stand supprted Ologe 5 speakers.
Leaning towards the DEBRA system since the (flatter?)
profile
woofers would probably take up less floor space.
Unless,...
Duke - are you building (or have built) a new sub array system for smaller rooms?
Thanks,
Hans |
Darn, we all seem to be agreeing. You guys are no fun:) |
Hello Duke,
Thanks for the clarification, it all makes a lot of sense to me.
It seems like your new system concept will probably work well not only in a variety of small rooms, but also some medium sized rooms. Plus, I'm sure you won't mind having a speaker system that has the very convenient and useful added benefit of working well in a hotel sized room.
Tim
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Hi Tim,
My reasoning is simply this: Four one-foot-square footprints (2 mains w/built-in subs + 2 separate subs) are easier to shoehorn into a really small room than six (two stand-mounted mains + four separate subs). And I already make the latter.
If we use a little bit of asymmetry in the placement of the main speakers those first two subs are now asymmetrical, even if they are tied to the main speakers. And we have other tricks up our sleeve if needed... such as polarity reversals, or adding a second amp and dialing in phase quadrature.
The main driver arrays are fairly directional so they can be placed close to the walls with relatively little downside. Compared to most small speakers, they have less need of distance from the walls in order to get good soundstage depth. So their requirements probably are not going to screw up subwoofer placement all that much.
And with four distributed subs, the specific locations of the individual subs are a lot less critical than with one or two subs. So imo there is less penalty from those first two subs being stuck underneath the main speakers.
I hope to end up with a competitive system for those who can accommodate four footprints in a small room.
Duke
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audiokinesis:"I’m working in a small-room optimized speaker system and surprise surprise it includes four small subs, two of which are built into the bottoms of the main speakers for the sake of practicality."
Hey Duke,
Very interesting. As I understand it. having main speakers with subs built-in can be an issue since main speakers are typically positioned in the room to optimize the midrange and treble response, along with the stereo and soundstage imaging, at the designated listening seat. This means the built-in subs, because they are housed in the same cabinet as the midrange and treble drivers and are restricted to being positioned at the exact same room positions as the midrange and treble drivers, which are unlikely to be the exact optimum sub room positions in the room for bass response performance at the designated listening seat.
Because I believe you know all of the above, I'm thinking your purpose for these two built-in subs is probably just to create numerous bass modes (peaks and dips)in the room.
Is your new small room concept based on the reasoning that placing the first two subs at the predetermined locations where the midrange and treble drivers perform best will typically be placed sufficiently that, with the additional two subs being capable of being placed optimally in combination with the two predetermined subs. the overall bass response in the room will be generally not be optimized but still exceptionally good?
If so, is the reason for not using four independent subs along with a pair of independently positioned and matched bookshelf type satellites just practicality?
Just curious,
Tim
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" What is the smallest room size recommended for use with the DEBRA/SWARM systems? "
This will be somewhat counter-intuitive, but a small room benefits more from a distributed multisub system than a large room does. The reason is, smaller rooms are correspondingly worse in the modal region and so they have more room for improvement!
So the large room starts out better. Assuming equivalent multisub systems in both, the small room will improve more and "catch up" to the larger room somewhat, but I would expect the larger room to still sound better.
I think the lower room size limit is set by practicality... when you can just barely shoehorn four small subs into the room along with the rest of the system and yourself, you have found the smallest room size.
I’m working in a small-room optimized speaker system and surprise surprise it includes four small subs, two of which are built into the bottoms of the main speakers for the sake of practicality.
Duke |
mijostyn:" Actually, it might work better in a small room. Every dimension in a room makes difference but perhaps less so with multiple subwoofers."
Hello Mike,
I believe you're correct. Very few people probably even consider, much less attempt, using multiple subs in a small room and are unaware this would be a good bass solution.
Tim
Report this |
Actually, it might work better in a small room. Every dimension in a room makes difference but perhaps less so with multiple subwoofers. |
Hello Hans,
I recall James and Duke agreeing that the 4-sub distributed bass array(DBA) concept actually works very well in small rooms. It's a bit ironic since multiple sub bass systems in small rooms are probably one of the least likely solutions most individuals would logically consider as a viable solution.
I don't believe there're set limits to domestic room sizes, floor materials or ceiling heights that a DEBRA/SWARM system will be effective in, it's more a matter of accommodating four 1' x 1' x 2' subs along the perimeter of the room facing the nearest wall. The main goal, counterintuitively, is to get as many bass modes (peaks and dips) distributed throughout the room as possible and rely on our brain's normal functioning to create the perception of smooth, detailed and natural bass that seamlessly blends with the main speakers. The concept works exceptionally well in virtually any room and with any pair of main speakers.
I think either James or Duke will offer an in-room home trial period, as James did for me, to make sure your room isn't one of the extremely rare rooms and systems it does not perform exceptionally well in. This makes it a very low risk purchase and it'll all be needless anyway since your room has no obvious issues. I'm fairly certain you'll be very glad if you decide to give either one a try.
Tim
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Hi Folks,
I just posted this question to James Romeyn on his website and thought I'd ask it again on this forum to seek your wisdom as well:
What is the smallest room size recommended for use with the DEBRA/SWARM systems?
Also, does ceiling height have any effect?
Thanks,
Hans |
mijostyn,
Oh yeah, sorry, I forgot you use a 4-sub line source bass array system. Well, then I'm sure you understand exactly what I mean when I describe a 4-sub bass array system as having a sense of bass ease that gives the impression of unlimited and natural bass power while also being capable of reproducing the impressive bass dynamics of music that one normally only perceives with music one hears played live in person. I'm also fairly certain you wouldn't want to only use only three subs, either.
Tim
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Tim, I use four subs.
Thanx Duke for the explanation. |
Mijostyn: "According to Earl Geddes... you want to keep your subs as far apart as possible and throw the fourth one away."
Duke:"The four-sub configuration I use was Earl’s first-generation multisub-system. He subsequently wrote a program that can analyze the outputs of three subs and design custom digital equalization filters that will attain his goals without needing that fourth sub. The drawback is, if you move any of your subs or buy a new sub or change rooms, you need to have Earl redo the equalization in order to return to optimization."
Hello Mike and Duke,
Even though I don't doubt Earl Geddes when he now states three subs are sufficient to constitute an effective DBA, I know there are other benefits of utilizing four subs in a DBA system in my room; namely the sense of bass ease along with the sense of the natural and unlimited bass power and impressive bass dynamics of music that I normally only perceive with music I hear played live in person. I wouldn't want to sacrifice that quality just to have one less inconspicuous sub in my room.
Tim
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Mijostyn wrote: "Duke I need you to define what you mean by a minimum phase system." I probably shouldn’t have used that term, as it sounds like I’m talking about phase response. You can google the term "minimum phase system" if you want. Instead of using the term I should have simply said something like this: At low frequencies, there is a correspondence between the frequency response and the in-room decay such that they track one another. When there is a frequency response peak, the corresponding decay time is longer. The correspondence is such that if we fix one, we simultaneously fix the other. Misostyn again: "Duke is saying is that placing subs randomly throughout the room creates a situation that smooths out the frequency response throughout the room." Just one minor point: I’m not really advocating RANDOM sub placement; I’m recommending DELIBERATELY ASYMMETRICAL and INTELLIGENT sub placement. Mijostyn: "According to Earl Geddes... you want to keep your subs as far apart as possible and throw the fourth one away." The four-sub configuration I use was Earl’s first-generation multisub-system. He subsequently wrote a program that can analyze the outputs of three subs and design custom digital equalization filters that will attain his goals without needing that fourth sub. The drawback is, if you move any of your subs or buy a new sub or change rooms, you need to have Earl redo the equalization in order to return to optimization. Hleeid wrote: "Still looking for comparisons between the Swarm and DEBRA systems." The only significant difference is the shape of the footprint: The Swarm units have a square footprint (12 inches by twelve inches), and the DEBRA has a rectangular footprint of approximately the same total area. The woofer is the same, the internal volume is virtually the same, and the port tuning frequency is the same. They use the same kind of long, pluggable port. In the Swarm, the downfiring port is behind the woofer, and in the DEBRA the downfiring port is alongside the woofer. Hence the different footprints, but I don’t think there is any corresponding difference in performance. Jim thought a rectangular footprint looks better, and he has a much more artistic eye than I do. I sent the Swarm to Robert Greene of The Absolute Sound for his evaluation, which is why the Swarm rather than the DEBRA has been named in three Golden Ear awards and a Product of the Year award. Duke |
Thanks ClioO9 and Tim!
I will try to contact both Duke and James.
Hans |
Hello Hans,
Clio09 is correct, both the Audio Kinesis Debra and Swarm 4-sub DBA systems are very similar and perform almost identically. James Romeyn and Duke Lejeune are friends and are business associates in Audio Kinesis.
James is located in Utah and, as I understand it, he licenses the Audio Kinesis brand name for his Debra 4-sub DBA system with Duke’s approval. Duke owns Audio Kinesis, is located in Texas and designed, manufactures and sells his Swarm 4-sub DBA system.
Both are excellent systems, use an identical amp/control unit and use identical 10" aluminum long-throw woofers in their subs. However, I believe they both have local third party woodworking companies build the actual sub cabinets and assemble the subs. I believe this is the reason the Debra subs are a few inches taller and wider than the Swarm subs.
They both come with removable port plugs that allow configuring them as either sealed or ported subs, soft rubber footers for hard surface flooring and spiked metal footers for carpeted flooring as well as having the speaker wire connections located on the bottom for concealing the connections for a clean look. These subs actually are designed for the front firing woofers to face, and be only a couple of inches away from, the nearest wall. They all perform great this way and all that’s visible are nice clean pedestals in the wood of your choice.
I just happened to initially learn about the 4-sub DBA concept through conversations with James and, as a result, decided to purchase and give his Debra system a free 28-day in-home tryout before ever even knowing of Duke’s Swarm system. I’d also recommend calling either or both James and Duke to discuss your specific situation. They’re both very friendly, knowledgeable and helpful.
Best wishes,
Tim
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Since James Romeyn (DEBRA) and Duke LeJeune (Swarm) are friends and work together on projects I would say these two systems probably sound more similar (if not the same) than different. If you note, both set ups use the same bass amp/active crossover. Perhaps contacting either or both directly will get you some answers. IMO either would be good solutions in a small room.
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Hi folks,
Still looking for comparisons between the Swarm and DEBRA systems. Couldn't find much info.
Would one system work better than the other in a small room?
Thanks,
Hans |
Hello Mike,
If you're intuitive, you can probably guess what this word means just by looking at it. No? Maybe you're not so intuitive, after all. Intuitive means having the ability to know or understand something without any direct evidence or reasoning process. Your statement that "Now that I know what is going on it makes perfect sense and is indeed intuitive" defies logic; the very fact you required more information to fully understand the DBA concept proves it is NOT intuitive. I don't understand why you felt the need to rebut my statement that the DBA concept is counterintuitive, when it obviously is, but I suggest we just drop the whole subject and move on.
Thanks for explaining what you meant by having no rear wall, I get it now.
You stated: "I firmly believe that with any dipole speaker, Planar magnetic, ribbon or ESL you have to cross up higher at least at 100 Hz. This disqualifies a DBA. On the other hand my way of doing things may not work well with regular dynamic speakers. Pick your poison:)"
We seem to have different audio experiences and opinions but I think that's healthy since we both can benefit by discussing our differences. Even though you utilize a line source bass array system (LSBA) and I use a distributed bass array system (DBA), I believe it's a win-win scenario because we've both attained exceptionally good bass response performance in our rooms/systems along with also learning more about an alternative bass system solution.
In the spirit of benefiting from discussing our differences, I disagree with your statement that planar-magnetic dipole speakers need to use crossover frequencies of at least 100 Hz. I have planar-magnetic, dipole, 3-way Magnepan 2.7QR mains but they have decent bass extension, rated at 35 Hz +/- 3db. I run them full-range and usually cross them over to the 4 Swarm subs in the DBA at 40 Hz. This works very well in my system/room with the bass seamlessly integrated with my main speakers without any downside I'm aware of.
I think I understand your reasoning for suggesting using higher crossover frequencies on planar-magnetic, ribbon and electrostatic speakers. These speaker types don't typically have very deep bass extension and freeing both the speakers and the amp(s) driving them from the demanding requirements of reproducing deep bass are logically reasoned to improve the performance quality of both as a result.
This theory makes so much sense to me that I experimented with using crossover frequencies at various settings as high as 100 Hz, both with filtering out the low frequencies below the crossover setting and running the mains full-range. I stopped experimenting with higher crossover settings once I began perceiving the location of the subs at around 100 Hz and it began to have a negative affect on the normally very good stereo imaging of my mains.
I believe my system didn't gain the expected sound quality benefits of reducing the low frequency demands placed on my amps and speakers due to a couple of reasons. The first reason is the Magnepan 2.7QR mains I use are a 3-way design with rather large 625 square inch dipole bass sections that reproduce frequencies from their lower limit of 35 Hz to 650 Hz. But relieving these bass sections of reproducing the deepest bass frequencies in this range had no significant affect on the midrange and treble sections of these speakers. Also, any significant sound quality improvements in the bass sections' performance would be masked by the high quality bass reproduced by the Swarm bass system.
The second reason is that the D-Sonic class D mono-block amps I use for the mains deliver 1,200 watts into the Magnepans' fairly consistent 4 ohm loads. However, I still believe that systems using less powerful amps and speakers with simpler. less than 3-way, designs could realize significant overall sound quality improvements.
After extensive experimentation, I actually arrived at the opposite conclusion than you recommend, at least for my system. I thought my system sounded the best overall with the main speakers running full-range and the Swarm subs only becoming active on frequencies at or below a relatively deep 40 Hz and when the source content called for it.
I believe my system may perform even better overall with an even lower crossover frequency setting but 40 Hz is the lower limit on my sub amp/control unit.
My current thinking is that there are a number of good bass system solutions available, beginning with a pair of good quality subs, and that the choice of the optimum bass system, as well as its optimum configuration, is best determined on an individual basis.
Later,
Tim
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If my 2 RELs (run in mono) seemed to be lacking anything at the 58hz or so point where they match the bass rolloff of my main speakers, I'd consider the "swarm" system, although 4 boxes and the wires are somewhat off-putting. Also, my RELs cost about 200 bucks each used and are perfect, providing a 250 total watt low bass enhancement to the 12wpc SEP main amp, and it all works extremely well with no DSP needed. Big-ish room with very tall sloping ceiling (that helps keep bass sounding right). |
hleeid they are both doing the exactly the same thing but DEBRA is using bass reflex enclosures and Audiokinesis uses sealed enclosures. I would go with Audiokinesis for two reasons. 1st is I prefer sealed enclosures for subwoofers. 2nd is I just came from the DEBRA web site and the marketing was beyond belief.
Mike |
Ok. So after researching the wonderful resources about subwoofers, I think I am beginning to understand nodes, evenness, cancellation, etc. and leaning towards going with the Swarm again.
But Swarm or DEBRA? Not finding much info about the differences.
Anyone have experience comparing them?
Thanks,
Hans |
Tim, Once I read Gedde's explanation of how DBAs work it makes absolute sense. My problem was that Duke was using terms that I was not familiar with that were not self explanatory. He was talking in a language I did not understand. Now that I know what is going on it makes perfect sense and is indeed intuitive. However it has limitations the biggest one is that you have to keep the crossover under 60 Hz or it will start messing up your image. This may work well for people with regular point source speakers that get down to 40 Hz ok. I firmly believe that with any dipole speaker, Planar magnetic, ribbon or ESL you have to cross up higher at least at 100 Hz. This disqualifies a DBA. On the other hand my way of doing things may not work well with regular dynamic speakers. Pick your poison:)
My media room is 16 X 25 feet. The back wall is 75% open to the kitchen and then 30% open to the dinning room the back wall of which is 75 feet away. So, the back wall reflection is broken up all over the place. I designed it that way. Between my speakers is a 113" diagonal Stewart screen the idea being that I can either listen to music or watch TV while cooking and having dinner. The projector hangs from the ceiling.
Mike |
mijostyn: "Tim, in this case I don't think psycho-acoustics is the reason." "when a concept is counter intuitive it usually means it was not explained well."
Hello mijostyn/Mike,
I think we have different ideas concerning what qualifies as psychoacoustics. Psychoacoustics is the scientific study of sound perception and audiology—how humans perceive various sounds. More specifically, it is the branch of science studying the psychological and physiological responses associated with sound (including noise, speech and music). I think you're right, masking and volume could be construed as part of that definition, they're just not the primary examples that I usually think of.
I also believe my explanation of the DBA concept and the psychoacoustic dynamics involved was sufficient. When I stated the DBA concept is counterintuitive I was referring to the method of creating more bass peaks, dips and nulls in the room to eliminate the perception of all of them in the room, with our brains being used as a sort of natural room correction software and hardware. Do you think the DBA concept is intuitive? Don't you think the cognitive dynamics involved with the DBA concept fall within the definition and realm of psychoacoustics? You're correct, Geddes has stated that good in-room bass response can be attained over a wider area using as few as three subs and good at a single listening position using just two. Hopefully, Duke will respond to the bass phase issues. You have no rear wall in your room for bass soundwaves to reflect off of? You must have very good bass performance along with very high heating and cooling costs. Tim |
Tim, in this case I don't think psycho-acoustics is the reason. An example of psycho-acoustics is masking. MP3 compression strategies operate on this principle. The normal undistorted music masks the distortion because or brains can only pay attention to the loudest noise. If you don't want to hear your car rattle, turn on the radio.
Nodes form in rooms below what is called the Schroeder Frequency which depending on the size of the room is somewhere around 130 Hz.
Where the nodes are depend on the frequency, room size and the position of the woofer. By positioning the woofers at different places in the room you create nodes in different places which overlap at different phases creating what I think Duke is referring to as a minimum phase system. This is a bit of a tough one to explain but I will give it a shot. Draw a sine wave on paper now draw another one 10 degrees out of phase with the first. Keep drawing sine waves 10 degree off from the last one until you come around a full 360 degrees. Now lets say these sine waves represent volume. The very bottom is zero dB and the very top is 20 dB. If you average all of these sine waves what you get is a flat line at 10 db. Or as Duke implies a minimum phase system. Geddes seems to think that just three sine waves is enough to create reasonably flat response and you can do this at any frequency below 80 Hz because below 80 Hz you can not locate the source. I personally think that should be below 60 as I know for a fact me and my audiophile friends can locate a 60 Hz test tone. The problem with this approach is what about the frequency band up to the Schroeder Frequency? By absolute coincidence I cross over at 125 Hz just below the Schroeder point. So my subs have to deal with all the room nodes from 125 Hz down. Above the Schroeder Frequency nodes do not form. My way of dealing with the node problem is to limit the dispersion below 125 Hz by forming a line source that is right up against the front wall. Now there are only reflections off the ceiling and rear wall. In my case the rear wall is broken up or there really is not a rear wall. The nodes that do form are easily managed by room control. I am not sure this approach would work well with point source speakers. Such an array may overwhelm them.
When a concept is counter intuitive it usually means it was not explained well. |
Hello Mike,
You stated: "Simplifying the situation, what Duke is saying is that placing subs randomly throughout the room creates a situation that smooths out the frequency response throughout the room. I am trying to understand how that happens. "
Hopefully, Duke will respond, too. But as I understand it, the key to understanding how and why a distributed bass array (DBA) smooths out the bass frequency response is psychoacoustics, how the brain processes bass information in the room delivered through the ears, as well as through other body senses, and creates our perceptions of the bass.
The purpose of four independent, well distributed subs launching bass soundwaves into the room, with the full knowledge that these soundwaves can be relied upon to reflect off room boundaries and collide into themselves and one another until they run out of energy, is to create an abundance of bass room modes (bass peaks, dips and nulls) and then depend upon our brains to process, sort and make sense of the abundance of room modes in order to create an overall perception of the bass in the room. In other words and simpler terminology, psychoacoustic principles, which explains how the brain will sum the bass by frequency and average it out which results in our perception of the bass as smoothed out and natural.
I believe psychoacoustics are the key to understanding why and how the DBA concept works so well. It seems to me that explaining how and why a line source bass array (LSBA?) concept works so well can be done more easily with just physics than the DBA concept can and the LSBA concept seems to rely much less on psychoacoustic dynamics than the DBA concept does. I think psychoacoustic principles and dynamics are a bit esoteric and counterintuitive.
I've never experienced the bass response performance of an LSBA system in any room. I know the first time I experienced the bass response performance of a DBA system in my room it was a revelation and uncanny how well it performed. I'd love to experience a LSBA system some day soon since I believe it could also be a revelation.
I share your curiosity about whether I would detect any difference in bass performance with my DBA by limiting the distance between subs to under 14 feet. However, in 2008 I had a stroke and still don't have full mobility of my left arm and leg. I also had custom length speaker wires made for all four subs and the wiring is all run and hidden in the crawl space below my room. Due to these factors,unfortunately, I don't think it's practical for me to experiment anytime soon. Perhaps I could recruit a fellow audio enthusiast friend as an experimental lab assistant and mover but no promises.
Tim
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