Hello vinnydabully, What you apparently discovered by accident is called a 4-sub distributed bass array system. The key is having 4 subs and I've been using one for the last 4 yrs with large Magnepan panels. The Audio Kinesis Swarm and Debra are complete 4-sub DBA systems that sell for about $2,800, and the 4-sub DBA concept works like a charm. Here's an Absolute Sound review of the Swarm: https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/ As you've discovered, you can create your own custom DBA using whatever 4 subs you prefer. The concept is based on scientific research done by Dr. Earl Geddes and Dr. Floyd Toole. I and others have started threads on how well this concept works: https://forum.audiogon.com/discussions/anyone-else-using-an-audio-kinesis-swarm-or-debra-distributed... You can google 'distributed bass array', 'geddes' or 'toole' if you'd like to read more. Tim |
m-db,
I'm sure you'll be thrilled to know that setting up a 4-sub distributed bass array system requires absolutely no bass room treatments, mics, DSP and room correction software or hardware. Room correction is completely optional.
It's also scalable since you can use any 4 subs to achieve accurate, smooth and detailed bass with your choice of available bass power, dynamics and impact, from 4 small DIY subs to 4 JL Audio Fathom V2s and any bass quality and capacity levels in between.
Since there's currently no recorded vinyl or disc source material with bass content below 20 Hz, I'm using (4) two foot tall ported subs with one sq. ft. footprints and 10" long-throw aluminum drivers that are flat down to 20 Hz at 113 dbs.
My DBA system provides accurate, detailed, smooth and natural bass that integrates seamlessly with my 6x2 ft. fast Magnepan panel speakers which are only capable of bass extension down to 35 Hz. It works like a charm for music and ht.
Tim
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Yes, the downside of using a custom DBA with 4 amplified subs is the need to adjust the volume, xover frequency and phase on each individually and do a lot of tweaking til you get it just right.
Buying the complete Audio Kinesis Swarm or Debra DBA kit for $2,800 has the advantage of these controls being set on the sub amp that controls the configuration on all 4 passive (no internal amp) subs as a group. You also only need a single a/c outlet for the amp as opposed to 4 outlets for subs with internal amps.
My room has a crawl space below and I ran all the connecting sub and amp speaker cabling through that.
I also agree with setting the xover frequency as low as possible for best integration with the main speakers.
Tim
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firstnot:" Swarm + Room Correction and you are set. Cost about $7k new.
$3.5k used. $1.0 for the very patient smart shopper."
Correction:
Swarm + No Room Correction required and you are set. Cost about $2,800 new, including 4 ported subs with port plugs and 1,000 watt class AB sub amp with controls for volume, phase and single band eq.
No used price known due to it being the last sub system you'll ever need or want.
Tim
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bdp24:
"The plate amps in the Rythmik subs provide all the controls mentioned by @Noble100: volume, phase (180 degrees via a continuously-variable rotary knob), x/o frequency (40-120Hz) and slope (2nd/4th order), plus damping, a rumble filter, one band of PEQ, and both line level (RCA jacks) and speaker level (binding posts) hook-up. There is no reason four of them cannot be implemented as a swarm. You will however need four AC outlets. ;-)"
Hello bdp24,
When did I state that you can't use four Rythmik subs in a swarm type (4-sub distributed bass array) system?
The answer is I didn't. You can use any 4 self amplified subs you'd like to create a custom DBA system.
What I stated is that, if you choose to use 4 self amplified subs (like the Rythmik) to create a custom DBA rather than an Audio Kinesis Swarm or Debra complete kit DBA (which consists of 4 passive subs and a separate amp/control unit to power and configure all 4 subs as a group), then the setting of the volume, xover frequency and phase controls will need to be done individually for each sub rather than all at once as a 4 sub group on the AK sub amp/control unit.
My intent being only to inform readers of this fact so they can make an informed decision on whether to choose between a custom DBA system using 4 self amplified subs and a complete custom or AK DBA system using 4 passive (unamplified) subs.
In fact, I believe using 4 self amplified subs, like the Rythmic with individual volume/xover/phase controls, does offer more configuration flexibility than setting all these controls for all 4 passive subs as a group on a sub amplifier/control unit. It's just that it complicates DBA configuration, requires more time and is an individual choice best made with full knowledge.
The key to the DBA concept working so amazingly well is the use of at least 4 properly positioned subs, the fact that it works extremely well with a wide variety of sub types, sizes and quality just demonstrates the validity and flexibility of the DBA concept.
Tim
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I thought it would be useful to cut and paste a response from Duke Lejeune, owner of Audio Kinesis and advocate of the DBA system concept, from a thread I started awhile ago on the DBA concept. Here's a link to the full thread followed by Duke's relevant response: https://forum.audiogon.com/discussions/anyone-else-using-an-audio-kinesis-swarm-or-debra-distributed...
Duke:
"Just for the record, I got the distributed multisub idea from Earl Geddes. It happened like this: I was driving Earl to the airport after CES in January of 2006 and we were stopped at a stoplight. He said to me "Duke, I’ve figured out how to get good bass in a small room. Use four small subs and distribute them asymmetrically. Each will produce a different room-interaction peak-and-dip pattern, and the sum of the four dissimilar peak-and-dip patterns will be much smoother than any one alone." A lightbulb went off in my head as I immediately realized this was "the answer", so I said, "Can I license that idea from you?" He replied, "You can just use it." And then the light changed. It was that fast. Now let me explain what I meant by "the answer": For years I had been trying, off and on, to build a subwoofer that was "fast enough" to keep up with Quads and Maggies. I was a SoundLab dealer, and the SoundLabs are big enough to have good low-end extension, but they are too big and expensive for most people. I figured the first guy to make a sufficiently "fast" sub would have a potential market among Quad and Maggie owners. Being a longtime amateur speaker builder, I tried pretty much everything except for a horn: Sealed boxes, aperiodics, low-tuned vented boxes, transmission lines of many different geometries, equalized dipoles, and isobarics. None of them could "keep up" with Maggies and Quads. I was stumped. But the problem was not the "speed" of the subwoofer - it was the peak-and-dip pattern that the room inevitably superimposed on the sub, which totally dominated the result. Yes some subs were audible improvements over others, but none could blend with Maggies or Quads without there being a distracting disconnect between the subjective lack of "speed" in the low bass and the rest of the spectrum. You see, woofer(s) + room = a minimum phase system at low frequencies. What this means is, the frequency response and the time-domain response track one another. In English: Where you have an in-room response PEAK is where the decay is SLOW, and it doesn’t matter how "fast" the woofer is. The good news is that, when you fix the frequency response you ALSO fix the time-domain response, and vice-versa! So, SMOOTH bass is FAST bass. This is why the lightbulb went off in my head when Earl described his idea to me. A distributed multisub system like the Debra or Swarm or your own set of four subs results in four (inevitably nasty) peak-and-dip patterns, but their sum will be much smoother than any one of them. Actually you will end up with MORE peaks and dips, which will be much smaller and much closer together. This "closer together" part is quite beneficial - the ear tends to average out peaks and dips that are within 1/3 octave of one another. So the subjective improvement is often greater than one would expect from merely eyeballing before-and-after curves. One of the things to be aware of if you’re going to "roll your own" distributed multisub system is this: At the upper end of the bass region the outputs of the subs will be combining in semi-random phase, but at the bottom end of the bass spectrum their outputs may well be combining in-phase or nearly so, if the longest room dimension is a small enough fraction of a wavelength. This results in a rising response as we go down in frequency (and remember that the time-domain response tracks the frequency response). So if you already have two subs that go real deep, you might do better by adding two more that do not go as deep. Or vice-versa. In the Debra and Swarm systems, the subs’ native response curve falls by about 3 dB per octave from 80 Hz down to 20 Hz. This approximately compensates for typical room gain. Then in most rooms we reverse the polarity of one of the subs (usually the one farthest from the main speakers), and this extends that semi-random-phase addition down into the bottom of the bass region, further smoothing the response and offsetting the rising bottom end that we would otherwise have. Also the down-firing ports on the Debra and Swarm modules are pluggable, converting the enclosure into a low-tuned sealed box, to give further adjustability (given that every room is different). And finally, the amp that we use has a single band of parametric EQ, in case there is still a peak at some frequency. Speaking of EQ, why not use a single sub with EQ to fix the frequency response curve, simultaneously fixing the time domain response? EQ works great at a single listening position, and can work well within a small listening area. But the larger the listening area that we try to improve with EQ, the smaller the improvements are going to be. This is because the afore-mentioned room-induced peak-and-dip pattern changes dramatically as we change locations within the room ,so EQing a single subs works best for a single location. Unfortunately when we fix the frequency response in one location, we are making it MUCH WORSE in other locations! This is because the peaks and dips are at different frequencies at other locations. But with a distributed multi-sub system, the spatial variation (difference in frequency response from one location to another) is also greatly reduced. So if by chance there is still a peak with a distributed multi-sub system, chances are it’s a GLOBAL (room-wide) rather than a LOCAL peak, and therefore is a very good candidate for correction via equalization. Big rooms have smoother bass than small rooms because they have a more dense modal behavior: The room-induced peaks and dips are more numerous and more closely spaced. A distributed multisub system can make a small room mimic a larger room in the bass region by doing the same thing. And this will sound counter-intuitive, but the smaller the room, the more it will benefit from a distributed multi-sub system. One other bit of trivia: The other main researcher behind distributed multisub systems is Todd Welti of Harmon International. He investigated symmetrical rather than asymmetrical arrangements. Anyway Earl and Todd were developing their ideas AT EXACTLY THE SAME TIME, but each was completely unaware of the other’s work. So I guess it was an idea whose time had come! Robert E. Greene of The Absolute Sound gave the Swarm a Golden Ear award again this year (It got a Product of the Year award back in 2015). So despite the passage of time, apparently the distributed multisub idea hasn’t become outdated. Duke dealer/manufacturer/caught in limbo?"
I think this explains why the time-domain is much less important on deep bass response than some seem to believe it to be. It also explains the importance of how our brains process the presence of multiple bass peaks and dips at multiple frequencies in a room, referred to as psycho-acoustics, which is a bit counterintuitive but is a crucial factor in how a DBA so successfully utilizes the differentiation between the physics of how deep bass very long soundwaves behave in a given room and how we perceive those soundwaves. I admit I don't understand this subject in detail but I can state with certainty that the concept produces what I consider state of the art bass response in my system and room without the use of any room correction software or hardware, DSP, equalization and bass room treatments. I know I'll always have this excellent deep bass foundation that seamlessly integrates with not only my current main speakers on music and ht, but it will do so equally well with any main speakers I may use in the future. I've found my huckleberry.
Tim |
jtcf:
"Unpacked the second set of subs this morning and fired em up.I haven’t fussed with finding perfect placement yet but it’s sounding really good already.The room is energized in a way that I can actually feel it on my skin.Not boomy or overblown whatsoever.Acoustic and electric bass sounds more natural and three dimensional.It’s one of those moments where I just relax and know that this is the way it’s supposed to feel.Like when you find the perfect compliment of tubes for your amp or get your speakers positioned perfectly.Sigh...there it is.
I was happy with the two subs but this is definitely a step up."
Excellent, welcome to the DBA system sota bass response club, jtcf! I know exactly how you feel, it really is like a revelation the first time you hear the stunning quality and integration of the bass produced by a good 4-sub DBA system in your system, with your music and in your room.
It really makes me wonder why this concept isn’t more widely known of and utilized, especially by Audiogon members.
Congratulations,
Tim
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m-db: "Tim, actually I'm more impressed than thrilled by the economy and positive user comments regarding your DBA Swarm system. You have created a user friendly solution to an often ill informed segment interested in true full range listening. " Hello m-bd, Thank you, but I didn't create the excellent DBA system solution. All the credit belongs to Dr. Earl Geddes, Dr Floyd Toole, Todd Welti, Duke Lejeune plus probably others I'm unaware of that also made contributions to the concept. My contribution was just to have the dumb luck to give the Audio Kinesis Debra 4-sub DBA system a try and almost immediately recognize how extraordinarily well it actually performed. The first time I experienced the quality of the bass reproduced by the 4-sub Debra DBA system and how seamlessly the bass integrated with my main speakers, I sincerely felt it was a revelation and an awakening to actually hear and physically feel this level of bass quality and integration with my music, on my system and in my room. Initially, all I wanted to do was enjoy my significantly upgraded system for hours upon hours on musical and ht content while constantly reminding myself how fortunate I was to have this DBA in my system. 4 years later, I'm still enjoying it just as much. After a few weeks of first experiencing the DBA's extraordinary bass performance, I came back to earth enough to be perplexed about why it took so long for me to learn of the DBA concept and why more Audiogon members apparently weren't aware of and utilizing DBA systems. At this point, I felt an obligation to get the word out about how exceptionally well this DBA system concept actually performed in my system/room and how it was likely to perform at least equally well in others' systems. So, I began by starting an Audiogon thread on the DBA concept linked to below: https://forum.audiogon.com/discussions/anyone-else-using-an-audio-kinesis-swarm-or-debra-distributed... I've also been trying to get out the word on the effectiveness of DBAs by consistently trying to post responses on threads on this site concerning the use of subs, such as this thread extolling their virtues. I'm not sure how successful I've been but I'm going to keep trying to spread the word. I find it very difficult to overstate how well the DBA system actually performs in my system, know it will do the same in any system regardless of the room and the main speakers used and believe it's too good of a bass solution not to eventually be well known and widely utilized. Tim |
bdp24:
"@noble100, I agree, you didn't state that you can't use four Rythmik subs in a swarm type system. Ya know what I didn't say? That you DID say that. Why do you think I think you think you did?"
Hello bdp24,
Okay, you may not have said it directly but it's a simple, unambiguous inference to make from your post comment in which you referenced myself, quoted below:
"The plate amps in the Rythmik subs provide all the controls mentioned by @Noble100: volume, phase (180 degrees via a continuously-variable rotary knob), x/o frequency (40-120Hz) and slope (2nd/4th order), plus damping, a rumble filter, one band of PEQ, and both line level (RCA jacks) and speaker level (binding posts) hook-up. There is no reason four of them cannot be implemented as a swarm. You will however need four AC outlets. ;-)"
In any case, I agree that four Rythmik subs implemented as a DBA have all the required controls and would likely result in a high quality bass system.
Thanks,
Tim
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mijostyn:
"Tim, I think you need to drop your Adderall dose:) Sub woofers are not more prevalent in high end audio because they add expense, they take up space and women do not like the looks. Not to mention that there are still many audiophiles who think sonically they are a detriment."
Hello mijostyn,
I'm not going to blame my Adderall dosage, it was probably due more to the multiple bottles of whiskey and all those speedballs.
Concerning your reasons why sub woofers aren't more prevalent in high end audio, you may be correct but I can only respond from my personal perspective. My subs were an added expense but worth every penny, they don't take up much space at 1x1x2 feet each with 2 not even visible positioned behind my panel speakers, my wife likes the looks of the other 2 that are visible and usually has a vase of fresh cut flowers on one of them.
I don't like referring to myself as an audiophile because it reminds me of a crusty old rich pretentious guy blindly following audio doctrines of dubious merit, like the audiophile purist doctrine that subs are sonically a detriment that I envision some audiophiles blindly believing in for decades but never bothering or daring to find out for themselves whether or not the dusty old doctrine even has merit.
I consider myself more of a practical, reasonable and independent sort with an open mind, a belief in the scientific method, an appreciation of high quality audio/video equipment but utmost a lover of music and movies who's constantly searching for and learning about improved methods of reproducing both in my home system. Perhaps I'm such an avid fan of the 4-sub DBA concept because it's so compatible with my concept of myself.
You've had a very practical and interesting history with speakers and subs. I consider Apogees and Acoustats to be very similar to Magnepans, excellent fast type speakers that are a bit lacking in deep bass impact and dynamics that are also all recognized as being difficult to successfully integrate subs with.
I'm very curious how well those 4 Dayton subs you built would have integrated with those speakers if you were aware of and utilized the DBA concept in configuring and positioning them. Based on my knowledge and experience, I think it's likely they'd have worked very well.
Tim
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Hello mijostyn,
Very unusual and interesting. I think I understand your setup but I'd love to see a picture. Or you could fill out the system section on your profile and upload pictures for future reference.
The way I understand it, you're main speakers are ESLs (Quad ESL63s or possibly even a newer model?) that are positioned about 3 feet out from your front 16 ft. wall. All four of your Dayton subs have front firing 12" drivers that are facing the walls, 2 between the ESLs and 1 near the front of each L+R side wall, perpendicular to the side of each L+R ESL speaker (the null area) and facing the wall. Am I correct?
My subs are all front firing subs with the drivers facing the wall but have 10" drivers as opposed to your 12" drivers. I also have 2 subs along my front 16' wall with one positioned behind each of my 6 x 2 ft. Magnepan panels that are straddling a large hdtv, about 8 feet apart and 4 feet out from the front wall. There's also a sub along each of my 23 foot side walls with the left sub about 1 ft away from the left rear corner and the other about 2 ft away from the right rear corner. My listening seat is in the middle of the rear 16 ft rear wall and in between these 2 rear subs. Even though there's a sub on each side of my listening chair within 8 ft away, I never perceive the bass as originating from either one (no localization of bass).
You're using a linear bass array configuration and I'm using a distributed bass array configuration, but it sounds like we're both getting very similar high quality performance results; accurate, detailed and extended bass response with no standing waves you can hear and seamless integration.
I'm interested in your system and was wondering about your room dimensions, what you use for bass management and whether you use it for music only or ht, too.
Thanks,
Tim
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Hello mijostyn,
Thanks for the clarifications on your system. I know 'ESL' is usually an acronym for electrostatic loudspeaker but mistakenly thought the Acoustat 2 + 2 were planar-magnetic speakers. I now understand they're ESLs with the '2 + 2' designating there are two 94" tall panels utilized for each channel, meaning they're technically not a pair of speakers but a quartet of speakers. My mistake.
Ever since I bought my 2.7QRs used about 2001 I've been experimenting with single and dual subs in an attempt to incorporate good bass response and impact in the 20-35 Hz range I knew they were lacking. After a lot of research and some luck, this led to my learning of the 4-sub distributed bass array (DBA) concept and buying the Audio Kinesis Debra 4-sub DBA system on a trial basis about 4 yrs ago.
My current thinking is that this DBA system has provided such accurate, detailed, smooth, natural, dynamic and extended bass down to being flat at 20 Hz while also seamlessly integrating with the quality and speed of my planar speakers in my room, that I honestly feel very fortunate to have this high a level of bass quality in my system.
I realize, however, that a linear bass array sub configuration could provide even better bass performance in my system and room than my distributed bass array.
I'm hesitant to find out, though, for several reasons. I have a much better comfort level with the distributed array concept due to a better understanding of the physics and psycho acoustics involved than I do with the linear array concept, the distributed array is already completely hooked up and working extremely well and my wife and I are also very pleased that the 4 subs in my room are currently so physically inconspicuous and well integrated into our combination living, music and ht room. In addition, it would likely take a large room rearrangement just to give the linear bass array a try and there's no guarantee I would prefer it either.
I wanted to respond to your questions and suggestions from your last post, too. My listening chair is backed up to and centered along my room's 16' rear wall. But I move it about 3 feet out into the room for serious and prolonged listening sessions for better soundstage imaging. My panels are always a minimum of 3 feet and sometimes more away from the pair of subs behind them. Both sub 10" drivers are also facing the front wall and not directly into the back of these panels. I notice no detrimental effect in any frequency range from this positioning.
You also stated: "You have two subs back there with you and you hear those fractionally before you hear the ones on the front wall. This will smear transients. You want to hear all your subs at exactly the same time."
It's my understanding that the time-domain on frequencies under 100 Hz are not as critical as some believe. I also read an article on an experiment proving we don't even detect deep bass sounds until the entire frequency soundwave cycle exists in the room. The experiment consisted of subjects wearing headphones. A series of computer generated partial and full cycle deep bass tone soundwaves were played and the subjects only were able to detect the bass tones in which the full cycle was played and no sound at all when the partial cycles were played. As you know, it takes some time and distance for a full 56 foot long 20 Hz soundwave to develop in a 23 x16 foot room.
Tim
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avanti1960,
You may want to try the 'room crawl method'. Place your sub at your listening position, play some music with good and repetitive bass and walk around the perimeter of your room counter-clockwise starting at the front right corner. Walk slowly listening for an exact spot where the bass sounds best to you (accurate, detailed and natural). When you find this spot in your room, just move the sub to that position and verify the bass sounds good from your listening seat. You can use your RTA at this point for fine tuning if you'd like.
If you prefer good bass response throughout your entire room, and not just at your listening seat, the only solution I'm aware of is a 4-sub DBA system.
Tim
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zarathu,
I wasn't implying speaker and sub line array configurations don't work well, I know they do. I was just stating these arrays are best for a dedicated room or stage, using them in a living room requires serious rearrangement of the décor.
Tim
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"I have recently added 2 more 21 inches subs to the existing 2 12 inches subs to my main speakers. I find that the system sound more engaging with just the 21 inches subs. Maybe the subs are out of phase with each other. I do not know how to integrate them."
khiak,
I think you're saying you have four total subs (two 21" subs and two 12" subs) and like the sound with just the two 21" subs and no 12" subs in your system. Is this correct?
Tim
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Hello khiak,
Those Funk Audio 21.0LX are beautiful subs but they're really meant for a larger room. If you live in an apartment, your neighbors are going to hate you if you start using those in your room. If you really want to use those in your room, you'll need to keep them turned to a low volume to work well in a 4-sub DBA. I currently think the best solution for your room size would be 4 subs with single 12" drivers. A few more questions:
I'm having trouble looking up the JL 212 V1, is the model# F212 V1?
Do they have single 12" drivers or dual 12" drivers?
Would you be able and willing to return the big Funk Audio subs to achieve better overall bass in your room?
It sounds like your main speakers and rack are along the long 18 ft wall with your listening chair, with 3 seats behind, along the opposite 18 ft wall. Is this correct?
Are you planning on moving to a bigger place or home soon?
Thanks,
Tim |
Hello khiak,
What are the dimensions of your room (length x width x ceiling height)? What are the brands and model numbers of your subs?
You can definitely achieve very good bass response at a single dedicated listening seat with 2 subs. Using the 'room crawl method', described to avanti1960 earlier, in a sequential manner (first sub#1 and then sub#2) is probably the best way to position them.
In my experience, 2 subs will provide much better bass performance than 1 but in my opinion 4 subs will provide the best bass performance since line array sub configurations are not well suited for small rooms like distributed array sub configurations are.
The 4-sub DBA system concept works incredibly well in virtually any room and actually is perceived as making a small room seem like a larger room.
The key to a DBA system being such an exceptionally high quality bass solution is the use of 4 subs; the brand/model, size, power, price and type (self amplified or passive) are much less important than the fact that there are 4 of them active in the room. There are also no requirements that all subs are identical and subs of varying driver sizes, power, prices, types and bass extension are viable.
If you have a smaller room, however, I'm curious why you chose to add 2 subs with large 21" drivers when adding 2 more subs with 12" drivers is more logical and physically suitable?
Tim
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Hello khiak,
Well, you have four very high quality subs which you should be able to position and configure into a very high quality 4-sub distributed bass array system for music and ht.
I'm willing to assist you in this process but I want to warn you it's going to take some work and trial and error experimenting to properly position and configure the settings.
If you'd like me to assist you, I just need to know a few more things before we get started. It sounds like you have a screen and projector for video setup on the opposite 18 ft walls. So, I need you to confirm this and describe the rest of your audio/video equipment:
1. All your receivers, amps, preamps,surround sound processors, turntables, cd players, video players and any other hardware you use.
2. All equipment and storage racks.
3. The main speakers, center channel and surround speakers you use.
4. Any room treatments you currently use such as carpets,bass traps and absorption or diffusor panels.
Tim
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Hello m-db,
Thanks for your information. I'll look at the manual on Funk Audio's website to learn more.
He has four very high quality and expensive subs. The 4-sub DBA concept works exceptionally well even without room control. Do you use 4 subs in your system and room control?
If so, I'm interested in learning what specific additional bass performance improvements you noticed beyond the typical bass quality improvements gained from using the 4-sub DBA system. In other words, what specific bass quality improvements did you notice after applying the room control?
Thanks,
Tim
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Hello khiak,
Well, you certainly have some excellent and expensive audio equipment in your system. My system is a starter system in comparison to yours but I still believe my knowledge and experience with 4-sub distributed bass array (DBA) systems can be of benefit to you.
I'm running into a few issues while determining the best bass solution given your current room and equipment. My concern is you may be hesitant to adopt some of my suggestions because you've obviously invested a lot of money in a few of these areas and some may require room rearrangements.
I thought it would be best if I just described these issues in a straightforward manner with the assurance I'm not criticizing you by doing so. My intention is just to learn more about your system's development, better understand your room requirements, get your thoughts and discuss as necessary before proceeding. I'll assume you agree with this approach and begin describing these issues:
1. Why do you have so many bass traps in your room?
I fail to see the reasoning of having 4 high quality subs producing high quality bass energy in your room only to have much of this bass energy absorbed by numerous large and expensive bass traps positioned around your room.
One of the major benefits of using a 4-sub DBA system is that it eliminates the need for all bass room treatments. I currently use the Audio Kinesis Debra (identical to the AK Swarm but with slightly narrower subs) 4-sub DBA system in my room and the only bass room treatment I have is wall to wall carpeting. Do you have hard surface or carpeted floors in your room?
The above is the description of the 1st issue I wanted to address with you. My initial suggestion is to remove all of the bass traps currently in your room. They're not only not necessary, this would also free up a lot of floor space for optimum positioning of your 4 subs.
I know these bass traps are expensive but I really don't think they're doing anything to improve the perceived bass response in your room, although I'm sure an ASC sales rep would disagree. Are you okay with removing all your bass traps?
It sounds like your 21.0LX subs are on the left wall in front of your equipment deck and near your left Kharma main speaker. Both of them? Are they currently hooked up and running or just stored there for now?
2. My current thinking is you place both 21.0LX subs on the front wall, replacing your JL subs. Set each sub's delay and phase setting to zero and adjust the volume and xover frequency identically for both until the bass sounds the best to you at your listening seat.
Then place a JL sub on each left and right wall, about 1-3 feet away from the rear corners and, with both front subs running, set each sub's room control to "off" and phase setting to zero and adjust the volume and xover frequency identically for both until the bass sounds best to you at your listening seat.
Of course, having an assistant make the adjustments as you evaluate the sound will be very helpful. Once the bass sounds very good to you at your listening seat, adjust the phase control on each sub, in sequence one at a time, to check if altering the phase on any single sub improves the overall bass even further. If not, just leave them all set to zero which is in-phase.
A 2nd option could be using what M-db also mentioned about JL Audio currently marketing a version 2 room processing and a separate CR-1 Crossover component which could be useful just in case the above configuration and sub positioning doesn't provide excellent bass response performance in your room. I'm going to check this out and see if it'd be useful for your scenario.
A 3rd option could be the method I used for positioning each sub, which involves a sequential positioning I can explain later if needed.
Please let me know your thoughts, comments and questions.
Tim
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clio09: " @noble100, my speakers are the Model 2, mijostyn has the 2+2. I doubt my speakers go down to 28 Hz, but regardless I am cutting them off at 100 Hz. IIRC I think Duke recommends running the mains full range and set the frequency on the Swarm accordingly. If I am wrong about that I apologize to him in advance. I could run my system that way, but I prefer to follow Roger's method and treat the panels as if they were designed to only go down to 100 Hz. As for your amp, measure it. That will tell you what you need to know." Hello clio09, My mistake. Your Acoustat model two's specs state they go down to 30 Hz, which means our speakers are even more similar in their low frequency limits than I originally thought, 28 Hz for yours and 35 Hz for mine. So, I believe everything I stated in my last post still applies. I know the xover frequency and volume controls and settings are the key adjustments that need to be set properly for my DBA system subs to blend seamlessly with my main speakers. I do use Duke's recommendation of running my mains full range and usually set the xover frequency on the Swarm/Debra accordingly, which in my room and with my speakers seems to be about 45 Hz. I just tried raising my xover to 100 Hz on my system as a test. The most noticeable effect this had was to change my system's normally 3D soundstage imaging into a 2D soundstage image. It flattened out the soundstage similar to the difference between looking at a real life live scene and a video of it. It was much less realistic and enjoyable. I think I know the cause and effect of this change in perception but want to think about it a bit more thoroughly before explaining it in words. In my opinion, the ability of a high quality audio system to create a solid and stable three dimensional soundstage illusion in our rooms through a pair of properly positioned speakers, with the assistance of our brains and a well engineered recording, is one of the most enjoyable experiences to strive for in this hobby. I've discovered that my 4-sub DBA system, by adding the accurate reproduction of the lowest audible bass frequencies it was lacking from about 20-35Hz, significantly enhances this 3D soundstage illusion by causing it to sound even more life-like and palpable. The increased bass detail,the increased bass dynamics and impact that can be felt as well as heard along with this added bass output seamlessly blending with the quality of the rest of the audio spectrum being reproduced by my main speakers also contributes to this realistic portrayal. As I've stated, I'm extremely satisfied with my DBA system's performance and my wife's very pleased with its inconspicuous presence in our living room. I'm not claiming a 4-sub DBA system is superior to a line array bass system in bass performance but it certainly is when judged in the living room inconspicuousness and swimsuit competition stages of the sub system contest. Tim |
Hello khiak,
I just sent you a personal message. You should see a 'dialogue bubble' icon on the upper-right side of your screen, next to the 'shopping cart' icon. Just click on that and my pm should show. Click on my pm and I think you can hit reply and attach your video clip before sending.
I'll re-post on this thread once I receive it.
Tim
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mijostyn:
" I can not believe people are so far off on the subject of time and phase. Time and phase are intimately related. wire two of your subs backwards and see what you get. That is 180 degrees out of phase."
Hello mijostyn,
It seems we still have a misunderstanding about time and phase on deep bass sound waves. I believe, at the core of this misunderstanding, is that you're referring to arrival times of deep bass tone frequency soundwaves at the listening position and assuming that the effects of these deep bass soundwave arrival timing are just as critical as they are with midrange and treble tone frequency soundwaves.
The owner and speaker designer at Audio Kinesis, Duke Lejeune, has stated that the arrival timing of deep bass tone frequency soundwaves at the listening position are much less critical than the arrival timing at the listening position of midrange and treble frequency soundwaves. He stated the reason is the extreme differences in the physical length of these sound waves: a 20 Hz bass soundwave is about 56 ft long, a 2,000 Hz midrange sound wave is about 6.75 inches long and a 20,000 Hz soundwave is a fraction of an inch long.
I wanted to include a prior post in which I responded to another question from you concerning the time-domain of bass soundwaves that contains similar and some additional relevant info:
mijostyn: "You have two subs back there with you and you hear those fractionally before you hear the ones on the front wall. This will smear transients. You want to hear all your subs at exactly the same time."
It's my understanding that the time-domain on frequencies under 100 Hz are not as critical as some believe. I also read an article on an experiment proving we don't even detect deep bass sounds until the entire frequency soundwave cycle exists in the room. The experiment consisted of subjects wearing headphones. A series of computer generated partial and full cycle deep bass tone soundwaves were played and the subjects only were able to detect the bass tones in which the full cycle was played and no sound at all when the partial cycles were played. As you know, it takes some time and distance for a full 56 foot long 20 Hz soundwave to develop in a 23 x16 foot room.
I realize the importance of correct phase in audio reproduction but admit only having a basic understanding. All 4 of my Audio Kinesis Debra DBA subs are operating in mono and in-phase configurations. Once all 4 of my subs were optimally positioned, however, I followed the procedures by reversing phase on each sub sequentially, one at a time, to verify whether or not the overall bass response improved with one specific sub's phase reversed. I noticed no improvement with any single sub's phase reversed and, therefore, maintained operating them all configured as in-phase.
The above is what I learned from scientific research results conducted by acoustical experts Dr. Earl Geddes and Dr. Floyd Toole and Duke Lejeune's posts and writings. I believe everything I've stated is accurate but you could always refer to their writings if you'd like to verify or learn more.
Tim
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Hello m-db,
Thanks for the additional info. I do understand your point about subwoofer DSP room correction differing among manufacturers as well as differing by version from the same manufacturers.
I only have limited sub DSP room correction knowledge and experience, mainly gained from helping install and configure subs in the systems of friends and family. My 4-sub Audio Kinesis Debra DBA system has provided exceptional bass results in my room without utilizing any DSP room correction or room treatments and I believe this can be accomplished in any room and with any pair of main speakers.
Khiak has 4 exceptionally good subs, two JL Audio F112s and two Funk Audio 21.0LXs, that utilize relatively basic DSP room correction (with the Funk Audio subs only using DSP to adjust signal delay times and not the more specific adjustments possible via parametric equalization) and my current thinking is that these subs could be used to form a very high quality custom 4-sub DBA system either with or without running their DSP room correction.
The main adjustments for good integration would be the manual settings on each sub for volume, xover frequency and phase. I used these exact same controls, although on my sub amp for all 4 subs running in mono mode simultaneously, to achieve excellent bass response and seamless integration. I'm unaware of any reason khiak couldn't get the same or even better results in his system and room.
Once all 4 subs are positioned and configured, he could always run room control, for a pair of subs at a time, to see if it improved the overall bass performance and just use the configuration he liked best.
But I think khiak was a bit shocked by my suggestion he should remove all the numerous and expensive bass traps he currently has installed around his room. I understand since they were likely a big investment but they actually are unnecessary and it would free up a lot of room space.
Tim
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mijostyn:
"Oh, and Tim. I am not saying that in certain situations a DBA system may not be the easiest way to reasonable bass performance. It may work reasonable well for many people. What I am saying is that in the end it will not produce the most accurate and realistic results but do to do so usually requires advanced digital speaker control that at this time costs at least $6K. If however you have a tape measure, some savvy and some luck, you might be able to get there without the computer. An important part of this hobby is being able to screw around with your system to see if you can get it to sound better and in doing so you learn. So, start screwing around!"
Hello mijostyn,
Incorrect, wrong and you're mistaken. Millercarbon absolutely knows you're wrong because he had the intelligence and cajones to give it a try. There's no need for expensive advanced digital speaker control gear, any other DSP or PEQ equipment, tape measures, meters, bass room treatments, voodoo, chants, snake oil, savvy or even luck.
The key ingredients are just a minimum of 4 subs , proper positioning of all 4 subs and some precise and time consuming listening, calibration and repeating of the volume, xover frequency and phase settings until it sounds just right.
I believe the root cause of our disagreement over the effectiveness of 4-sub distributed bass array systems is your lack of experience and familiarity with them.
Tim
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Hello mijostyn,
I’m running all 4 subs in mono with a xover frequency between 40-50 Hz and a filter slope of 12 db/octave, usually configured for a 40 Hz xover for music and 50 Hz for ht. My main speakers are Magnepan 2.7QRs that each have a 620 square inch planar-magnetic dipole bass section but they only extend down to 35 Hz. I run these full range with a pair of D-Sonic M3-600-M mono-blocks rated at 1,200 watts each at 4 ohms. This combo produces very accurate and high quality bass on their own but I added the AK Debra 4-sub DBA system for added bass impact and increased dynamics.
Since the 2 bass sections only extend down to 35 Hz, I don’t consider them extra subs in the room but I do think they help on the overall bass quantity and quality in my room; for example, hearing the initial pluck of an upright bass’s string followed by hearing the deeper bass produced by the body of the instrument and finally the natural decay.
Subjectively, I perceive the bass as very accurate in tone, detailed, extended, dynamic, smooth and natural with an impact that is felt as well as heard. I don’t detect any bass muddiness or have the sense that the bass is too slow, lagging behind or disconnected from the rest of the reproduced spectrum.
However, I’ve never had the in-room frequency response measured but I would be very surprised if it didn’t measure well. I do have pictures of my room and system on my profile if you’d care to look and my room is 23 x 16 feet with 8 foot ceilings.
Thanks,
Tim
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Hello clio09,
I'm very impressed with mijostyn's linear/line array sub system and I've never even heard one in a home system, although I'd love to.
I'm also very interested in in your bass system build with your Acoustats that mijostyn is very kindly assisting you with. I'm also very happy with my DBA system but would be tempted to try it if I had the clean slate of a dedicated room. My combo music and ht room is also my living room. My 4 subs are currently very inconspicuous in the room which I think is very cool, because you only hear and feel them when there's prominent bass content on music and ht being played, and my wife can live with.
As I understand line array bass systems, the subs would be aligned across the front wall of the room and my 6x2 foot Magnepans would also be positioned about 4-5 feet out from this front wall. I'd be okay with it but my wife's opinion of this in our living room would likely be expressed by a sturdy frying pan smacking my skull.
But I wish you only the best on your build clio09 and hope you and mijostyn enjoy your linear array bass systems very much.
Please do post updates.
Thanks,
Tim
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Hello clio09,
Wait a minute. What's your plan?
I thought your plan was switching to a line array with larger subs. Four new subs using 10" drivers sounds like your planning a dba.
Tim
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clio09:
"My subs were built a while back, mijostyn helped me set them up for optimal performance in the line array. His subs have quite a large footprint, as do his speakers which are probably the best Acoustat model in my opinion. They line array per mijostyn is actually a semi circle as opposed to all of the subs being against the front wall of the room. A very interesting set up and one that does require some attention to detail. I appreciate mijostyn’s patient with me.
In my room the DBA did work well for my needs, and it wasn’t a difficult system to set up. My only nit was that my room constraints didn’t allow me complete freedom to place the subs anywhere I wanted. The sound was quite good though. I am embarking on building 4 new subs using a 10" driver and look forward to going to the audio show in Long Beach to hear Duke’s Swarm in person."
Hello clio09,
I'm having difficulty following along with your posts. From your post quoted above, it seems you're switching from using a distributed bass array (DBA) to a line bass array system for your Acoustats and with mijostyn's help.
Then, in the very next paragraph, you state you're starting to build four new subs with 10" drivers and you're looking forward to hearing Duke's Swarm DBA system, which happens to utilize four subs with 10" drivers just like the four new subs you're about to start to building, at an audio show in Long Beach.
Don't you agree this might be a bit confusing to a reader, especially when you just stated you're in the process of switching from a distributed to a line array bass system?
But the confusion continues with your latest post from5/27/19:
"I use low pass and high pass filters in my active crossover, Linkwitz-Riley 4th order 24 dB slope. One reason this was chosen is that we wanted to keep deep male vocals out of the subs. The other reason had to do with the resonance of the 8" drivers which we wanted to keep above 100 Hz. This is the reason for a 0.3 cu. ft. box which is stuffed tightly with cotton batting. The last reason has more to do with Roger Modjeski’s ESL design which only goes down to 100 Hz but that is irrelevant to me as I use the Acoustats which he modified to create greater dispersion, but left the rest alone, sort of ;)"
Now you're discussing 8" drivers in 0.3 cu. ft. boxes stuffed with cotton batting that only extend down to 100 Hz? Would this even be considered a sub and how are these 'mid-bass woofers' even relevant to either the DBA or the line-array bass system you're using?
Can you please clarify?
Tim
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Helloclio09,
My perspective is that the DBA concept is one of several solutions for those looking to add or improve bass response in the 20-200 Hz range in their systems. You're correct that I have a certain devotion to the DBA concept solution. This is probably due to it being the solution I researched the most, the solution I have significant personal experience utilizing in my own system as well as the one that has currently worked the best in my system and room.
I realize my previous experience was limited to experimenting with single and dual sub solutions in my system, but I learned that 1 sub is better than none and that 2 subs are better than 1. Both restricted good bass response to the listening position area and I perceived the bass from both as being slower, lagging behind and disconnected from the rest of the frequency range being reproduced by my fast and detailed Magnepan 2.7QR planar-magnetic speakers. However, I noticed adding a 2nd sub did begin to make the bass seem smoother, a bit faster, less lagging and better integrated with the main speakers along with more impact and better dynamics. With the 4-sub DBA, everything improved significantly. The bass was very detailed, smooth, impactful and dynamic without any sense of lagging behind or being disconnected from the main speakers. Also, this excellent bass response was not limited to just the listening position area, it was equally good throughout my entire 23' x16' x8' room, including from all 6 seating and viewing positions within it.
So, yes I do admit I have a certain devotion to the DBA solution. But I'm not naïve or close-minded enough to believe it's the only or even the best solution. I haven't heard a line array bass solution and would prefer, as you apparently do, to personally experience any and all promising bass system solutions before declaring any particular one the best.
Unfortunately, I'm precluded from personally experiencing a good line array setup in my system due to a lack of a dedicated room and my wife's preference for our living room front wall not resembling the stage at a 9 Inch Nails concert. As all Audiogon Forum regulars know, however, the next best thing to personally building and experiencing a bass line array system for yourself is to listen very closely to the impressions of someone else who has. Which is why I'll be trying to follow your posts on your custom line array system and impressions closely.
I also have some comments and questions concerning your last post and your numbered clarifying descriptions of your system and future actions and plans. But I've blubbered on too long already, so I'll include those in a separate post soon.
Thanks,
Tim
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clio09,
In my last post I stated I had some comments and questions concerning your last post and your numbered clarifying descriptions of your system and future actions and plans. Here’s your post with my comments and questions added:
"@noble100 if it wasn’t clear let me try to clarify it for you.
1. "I’m building subs with 10" drivers for use as either a DBA or line array. It’s nice to have choices."
I agree, choices and options are nice to have. My four Audio Kinesis Debra DBA subs all have 10" aluminum long-throw drivers. These work well in my DBA system for music and ht, providing sufficient bass that can be felt as well as heard. These subs are ported but come with port plugs if you prefer to use sealed subs which some claim perform better on music.
.
My audio enthusiast friend, who assisted me with my DBA setup, and I both agreed that we perceived the bass as very similar whether run as sealed or ported subs on both music and ht content. There was no clear advantage we perceived on music content gained from utilizing the sealed sub configurations with the lone exception being we perceived the bass as slightly more extended running the subs as ported. We were both curious on whether using subs with 12" drivers would allow even further extension of the bass response along with increased dynamics and impact without compromising the excellent speed and resulting seamless integration with the main speakers.
2. My active crossover has LP and HP filters set at 100 Hz. So the HP output sends signals 100 Hz and above to the panels and the LP output sends signals below 100 Hz to the 4 subs. Direct drive amps power the panels, a solid state amp or moderately powered tube amp with good damping powers the subs.
I’m very curious about which moderately powered tube amp with good damping you use to power your subs?
I wouldn’t even consider a tube amp to power subs due to their generally low damping factors and their resulting poor ability to firmly control the movement of dynamic cone drivers, especially the precise starting and stopping required of larger and heavier bass drivers in subs. Solid state class D amps seem to me to be the ideal solution for driving subs; very powerful with extremely low distortion levels, great transient responses and extremely high damping factors that often exceed 1,000. They’re also smaller, lighter, less expensive, require less maintenance, run much cooler and are tremendously more electrically efficient than tube amps.
Sorry, but the use of tube amps to power subs really perplexes me. You must have a good reason you’re not utilizing class D amps, right?
3. My current subs use 8" drivers in a tightly stuffed 0.3 cu. ft. box. This was done to insure the resonance of the driver was above 100 Hz. If I set the crossover points to 150 Hz on my filters this would be an issue but since I’m using 100 Hz and anything below that is sent to the subs this falls below the resonance so it’s a good thing. I should note that this was designed by Roger Modjeski for his ESL speaker system and the subs easily extend down to 30 Hz. If you don’t know who Roger is look him up, his experience and reputation speak for itself.
A sub with a single 8" driver tightly stuffed in a tiny 0.3 cu. ft. box that extends down to only 30 Hz? Can this small creation even be accurately described as a sub? Please excuse me, but as a sub I think this can only be accurately described as pathetic, feeble, impotent and kind of unintentionally funny.
Tim
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Hello clio09, I've read about your Acoustat 2+2 electrostatic speakers mainly in the Stereophile review attached below but have never heard them myself. Based on this and their specs I've come to believe we're both looking for similar improvements in our system's bass response, namely a little more deep bass extension and improved deeper bass dynamics and impact. Your Acoustat 2+2 electrostatic panels have a bass extension limit of 28 Hz and my Magnepan 2.7QR planar-magnetic panels have a bass extension limit of 35 Hz. Fairly similar specs that would indicate they both would benefit from a sub system that would provide a little more deep bass extension down to the audible limit of 20 Hz and improved deep bass dynamics and impact. If this is the case, which I know it exactly describes the deep bass I thought was missing in my system, then what is required is a supplemental bass system that provides bass extension down to 20 Hz, has the reserve power to provide life-like bass dynamics and impact that are felt as well as heard along with the bass not being perceived as disconnected, slow and lagging behind the sound from the main speakers. I've found this last quality of providing bass that is detailed, smooth, dynamic and fast enough to blend seamlessly with our detailed, smooth and fast panel speakers is the most difficult but one of the best things a DBA system does. It seems like you're now discovering that a custom bass line array can also seamlessly integrate as well or even better than a DBA. Very interesting to know and I'd like to learn more. Btw, I am using that Dayton class AB kilowatt amp for my swarm. I feel like you're setting me up for something, but I'll bite anyways and ask. Why should I not use it? Thanks, Tim https://www.stereophile.com/content/acoustat-22-loudspeaker |
Hello khiak,
To see my pm to you do this:
Scroll up to your last post dated 5/29/19.
Click on the red square icon with the "K" in the middle.
Click on the "Marketplace Feedback" tab.
Click on the blue thought bubble icon.
Click on the message from noble100.
Attach your video clip and click 'send' or 'submit'.
If you can't do this for any reason, just post again and I'll reply with my suggestion.
Tim
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Hello atmasphere,
Thanks for the good info, I learned some good stuff.
Tim
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Hello o_holter,
James Romeyn at Audio Kinesis is the guy who convinced me to give the AK Debra 4-sub DBA system a 28-day free home trial. I started off a big skeptic but, after hearing the bass response in my room and system, I'm now probably one of their biggest proponents. By a wide margin the best bass I've ever experienced in my room and the integration with my large Magnepan panels is absolutely seamless.
I followed the Audio Kinesis Debra sub positioning procedure exactly and it turned out very well. However, their advice was to sequentially reverse the polarity on a sub at a time to determine if it improves overall system bass performance. After spending half a day setting up my DBA system I was a bit tired and wanted to listen to it. I figured I'd get to that step when I could. But that was over 4 years ago and my subs still sound great running in-phase, so I now consider this phase reversal step to be optional.
Tim
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Hello o_holter,
My room is 23'x16' with an 8' ceiling. I have some pictures posted on my profile if you want to take a look. It's a combo music and ht system.
I have a 65" hdtv wall mounted to the middle of the front 16' wall with my Magnepans straddling the tv,they're about 8' apart and 3-4' out from the front wall. My listening seat is in the middle of the rear 16' wall. The Magnepans are slightly toed-in and their axis cross at my position.
For serious music listening sessions, I usually move the Magnepans about 5-6' out from the front wall and with no toe-in. I then move my listening seat exactly between them and about 3-6' away from the midpoint between them. I find this positioning allows for an amazingly
three dimensional soundstage illusion on good recordings that is wide, deep, detailed, solid, stable and realistic.
You stated: "To get my former system time-coherent I had to place the Velodyne DD18 a bit in front of the main speakers, if I remember right. Not a good thing, in our living / listening room. Your Debra system seems much more flexible. Happy to hear it works so well. Maybe I could complete my system with half of it - two subs. Although I have neighbours who complain with too much bass."
It makes sense to emphasize the importance of time-coherence of midrange and treble tone frequencies, that is that midrange and treble soundwaves reach the listener at about the same time since these frequencies have soundwaves that are relatively short in length, measured in inches. It makes little sense to include deep bass tone frequencies in this emphasis on the importance of time-coherence, along with midrange and treble tone frequencies, since bass frequencies have soundwaves that are very long, measured in feet. A 20 Hz soundwave is 56 feet long, a 30 Hz is 38 feet long and a 40 Hz soundwave is 28 feet long. Expecting time-coherence of bass, midrange and treble tone frequencies, that is that bass, midrange and treble soundwaves reach the listener at about the same time makes little sense.
Here's a quote from Duke Lejeune, Audio Kinesis owner and maker of the Swarm bass system:
"Another factor is that it takes the
ear a fair amount of time to hear bass
frequencies. The ear cannot even detect the
presence of bass energy from less than one
full cycle, and it takes several cycles to
detect the pitch. So considering the
wavelengths and room dimensions, by the time
we can hear bass tones the room’s effect is
in full swing. Perceptually, in our home
listening rooms there is no such thing as
“direct sound” in the bass region; by the
time we even begin to hear it, it’s all
reverberant sound."
So, moving a sub in front of the main speakers likely makes little to no difference in the perception of bass response performance in a normal sized room.
I believe 2 subs will begin to provide smoother bass response, roughly twice as smooth as a single sub, but that 4 subs will be roughly twice as smooth as 2 subs.
Tim
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Hello holter,
I'm certainly no bass expert, either. James Romeyn mentioned to me how well his A K Debra system and its distributed bass array concept works and I just read all I could find out about the concept, mostly research done by Earl Geddes, Floyd Tool, Duke Lejeune and Todd Welti.
I learned a lot, its psychoacoustics basis made a lot of sense and James Romeyn's offer to let me try it out free in my room for a month convinced me to give it a try. I can't overstate how well the Debra/Swarm system works with my main speakers on music and ht.
You have a fairly large room at 20'x27', are already using A K main speakers and seem like an ideal candidate for a DBA system. I think you'll be amazed by the results. I'd suggest calling James Romeyn and see if he'll give you a 28-day in home trial period. I guarantee you won't be returning it.
Tim
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Hello holter,
I'm not very familiar with the Dream Maker speakers, although I've read good reviews on them. I don't think you'd need any more than 4 AK subs to get excellent bass response in your room. I think James would be the best person to talk to about combining the Dream Makers and a Debra bass system since he's very familiar with both.
Tim
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