I have noticed many posts with questions about adding subwoofers to an audio system. Why the fascination with subwoofers? I guess I understand why any audiophile would want to hear more tight bass in their audio system, but why add a subwoofer to an existing audio system when they don’t always perform well, are costly, and are difficult to integrate with the many varied speakers offered. Additionally, why wouldn’t any audiophile first choose a speaker with a well designed bass driver designed, engineered and BUILT INTO that same cabinet? If anyone’s speakers were not giving enough tight bass, why wouldn’t that person sell those speakers and buy a pair that does have tight bass?
Dear @noble100 : As the other gentleman I already posted you are loosing the main focus of bass management and you are doing because as lewinsky you are deffending some one that does not needs no one deffended him because no one is attacking him. Please read my last two posts. I only disclose facts, attacking no one in any case he is " attacking " him self for what he posted.
Last but not least: he has not first hand experiences with the subs overall subject in his own room/system.
In the other side I know very well whom is atmasphere and maybe better than you. Period.
When I first built my woofer system, it was designed(1980-81) to mate
well with my Acoustat Model IIIs. It’s worked seamlessly, with
everything(mostly planar) I’ve owned, since(various active crossovers,
amps and one driver change, but same transmission line cabinets).
My distributed array woofers are used with Acoustat Model IIs with the Acoustat direct drive amps and a Beveridge RM-3 active crossover. I feel it is very well integrated and also works well with other speakers (Quad ESL and Spendor 1/2e). I don't think Duke LeJeune gets the credit he deserves for following this path and his DBA design certainly inspired what I am doing today.
Of the response to my question that I have seen so far, I thinks Ralph's is notable for his reference of tight base as an artifact of sound reproduction.
Dear @pwhinson : You have great passive speakers but even those could be improved making changes/up-grading in the bass range.
I would like to know which is the frequency range ( wide. ) handled by that quasi-ribbon bass " module ". The specs says that from 25hz but does not mention a crossover frequency range and was not mentioned too if that 25hz is its +,- 3db point because if not then those 20.7 in reality perhaps goes not more than true flat 30hz.
Even that are quasi-ribbon design and normally low distortion levels exist true distortion levels in the kind of IMD developed by the bass driver that affects all the other non-true bass frequencies handled by that driver and this IMD generated could goes lower.
I know that the Magnepan designer does not like hybrids designs but other ribbons designs came with integrated subs and works really great.
From my point of view the noble 100 solutions are only an opinion and for me not the best option.
You said that maybe there is no much information below 25hz and I can tell you that even below 20 hz exist recorded information that's really valuable if youy room/system can shows it. The Swarms solution goes down to 20hz only: 18hz in ported/vented fashion or 22hz in sealed fashion. Is it a complete solution?, not for me: it's a quasi-solution.
The 20.7 crossover frequency is a must to have before you take any solution about . Subs are not only to have evenly low bass room/system response and goes deeper in the bass range but perhaps more important that those is to take that IMD distortion levels at minimum and with this your overall quality performance levels will go higher and you will enjoy those 20.7 better than ever before.
@clio09 - Personally; I’ve experienced more live music than reproduced, over the past few decades. As long as that, "artifact" closely resembles what I’ve heard and felt, in the presence of the real thing, I’m happy!
Dear @rodman99999 : As @bdp24 you explained very well in what you posted before. That " artifact " certainly means nothing about what clio ask before.
Noble 100 posted something very good as an audiophile, something like: " when you hear it you will know. "
For that " will know " we must to have a near field position live music experiences in different venues ( several of those experiences. ) and with different kind of MUSIC.
Obviously that clio has not those experiences because if he has it then why to ask for or maybe he only want to confirm what he knew. ! ? ! ? but if he knew then what about that " artifact ".
Certainly: artifact is not the answer for me but for he is the rigth one, good even that maybe he had not those experiences. Who knows?
I am out listening to live music once or twice a week. Living in the SF Bay Area there are no shortage of events, from local spots to well known venues. I've also been fortunate to record or obtain recordings of many of the events I attend.
I believe in many of the attributes used in the definition of "tight bass" that have been posted. It's the term itself I don't agree with. That was the reason I asked and why I felt Ralph's response was notable.
@clio09- That’s why I mentioned, "semantics". I’m envious of your location. Currently; I’m stuck in a culturally-challenged hick-town, after living the major portion of my life, between Cleveland and Orlando. No dearth in either local(unlike here), regardless of music genre desired. Happy Listening!
Dear @clio09 : Here a definition of the word artifact:
""" ar·ti·fact/ˈärdəfakt/noun
1.an object made by a human being, typically an item of cultural or historical interest."gold and silver artifacts"
2.something observed in a scientific investigation or experiment that is not naturally present but occurs as a result of the preparative or investigative procedure."widespread tissue infection may be a technical artifact"
do you think that what you listen at near field position ( this near field position is very important for the subject we are analizing. ) in live music experiences in different venues and with different kind of MUSIC is an " artifact " ?
because at least for me is the very first time in my life that I read that word in reference to bass management and I think rodman9 too.
What noble100 posted: " when you hear it you will know , has nothing to do with artifact " but gin if that’s what you understand after those several nearfield live MUSIC experiences it’s ok with me but think a little about.
Anyway, can we go on on the bass management whole subject?
Dear @pwhinson : """
point of 28hz. BUT of course there's just very little music down there...."""
there are a lot of recordings with usable music information below 20hz and in both formats: LP and CD's.
Some like these ( exist hundred of recordings, this is a enunciative list/examples. ):
almost all Telarc recordings that not only goes below 20hz but as low as 6hz-8hz like in the 1812 overture, many Reference Recordings as Dafos and Berlioz Fantastique, obviously organ scores by Bach and other composers, Sheffiel Labs in its Firebird recording and in other recordings by them, M&K D2D has some recordings too, many rock music recordings, two notables here are The Wall, Dark Side of the Moon, last live Hotel California recording, hundred of Original Soundtrack Motion Picture in CD and some in LP too like: Glory, 300, Gladiator, Vangelis 1842, Blade Runner ( first picture ), the old " The Mission, et, etc.
All those comes with information below 20hz and only if we own true subs that performs at least at 14hz-16hz can we " discover " the beauty of those recordings.
A true subs is not the one that goes to 20hz but the one that gows way down below 20hz with low THD.
To achive that subs needs at least 12" to move the air need to and very good design. Ideally subs need to have at least woofers from 14" and up.
For a 10" woofer ( as the four subs array posted here. ) is almost imposible to handled frequencies below 20hz at over 100dbs ( SPL. ) and with low THD kind of distortion.
Btw, one of the ribbon speakers I was refering in my other post to you was the Apogee that I live with for a couple of months at my place ( several years ago, when Apogee was the " week new speaker " name. ) with the Scintilla's powered by my Classé DR3-VDH that was one of the few amplifiers to handled the speaker so low impedance of 1 ohms or the like. Well I listen too several times through the audio distributor its top of the line that was a full range one with hybrid design due that came with a integrated subwoofer and I can tell you that contrary of what the Magnepan designer thinks performed excellent but I did not have the kind of money for buy it.
I'm not talking of the Diva that was a great performer too but about The Grand, here you can read that exist only fortunated 25 owners all over the world:
For a 10" woofer ( as the four subs array posted here. ) is almost
imposible to handled frequencies below 20hz at over 100dbs ( SPL. ) and
with low THD kind of distortion.
This statement is false.
The Swarm takes advantage of room boundary effects as explained on the audiokinesis.com website.
So, in my point of view no one with those four subs array really can listen all the information that is recorded in those LP/CD's because are not tue subs, have low bass but not the very low bass like true subs and believe it or not it makes a difference.
Dear @atmasphere : If the post is to me then I'm sorry but I don't get it. What do you try to say about what? Maybe you are rigth in your posts but I don't know to what you are refering to.
Here’s a great vinyl, containing some sustained, 16Hz, pedal notes. They also did a great job of capturing the hall acoustics. It worked nicely, in concert with a Spectrum Analyzer, for testing my woofer cabinets. Much more enjoyable, than Pink Noise. https://www.discogs.com/Virgil-Fox-The-Fox-Touch-Volume-One/release/2356270
@rauliruegas When I make comments regarding the sound or effectiveness of a thing in audio, if they are subjective in nature I use recordings that I made since I was there at the recording session and know how they are supposed to sound. I had the recordings produced on LP and CD.
It is the nature of this sort of thing that only I know how they are truly supposed to sound as would be the case for anyone who was at those recording sessions. For example if I say the Triplanar arm reproduces bass better than any other tone arm I've heard its because I was there and have the master tapes; other arms simply don't seem to get the bass right.
So my suggestion to you is simple- get some good quality recording gear and make your own recordings so you can make accurate statements about things rather than speculation posed as fact.
@rodman99999 used the term "tight" in regard to a subject near and dear to my heart, that of musical cohesion within the rhythm section of a band. That is one of the foremost criteria in assessing the quality of that section, and his use of the term tight in this instance was in regard to musical tightness, not bass tightness in a purely audio sense. However, the bass quality of a woofer or subwoofer can and does also effect the perceived "tightness" of a rhythm section.
One point about Ralph’s argument regarding bass tightness can be discussed in the terms speaker designers use: a woofer can be critically damped (0.7), over-damped (a lower number), or under-damped (a higher number). A designer who wants to get more perceived bass out of his speaker will under-damp it---at the cost of bass "looseness", while a designer who intends for his loudspeaker to be paired with a subwoofer may over-damp his speaker, knowing that the bass quantity sacrificed to achieve a higher bass quality will be compensated for by the sub.
An over-damped woofer may not reproduce all the timbre, tone, and resonance produced by a, say, upright bass, as the over-damping will mute those qualities. An under-damped one may produce lots of bass quantity, but it’s lack of bass quality may result in the loss of the touch and timing of the bass player (and the drummer's playing of his bass drum). That’s why the best speaker designers aim for the critically damped figure of 0.7, the optimum compromise.
"For a 10" woofer (as the four subs array posted here. ) is almost imposible to handled frequencies below 20hz at over 100dbs ( SPL. ) and with low THD kind of distortion."
I didn’t design the Swarm to go below 20 Hz, but several customers who have measured the in-room response report -3 dB in the upper teens. For deepest loudest bass at the same price point (three grand for the system), a single monster sub is the way to go. I have designed a Swarm that can do well over 120 dB at 13 Hz, but it’s not very practical and I don’t think there would be much market for it.
Each individual 10" Swarm unit can do about 100 dB at 20 Hz in-room at one meter without approaching x-max or amplifier clipping, assuming "typical" boundary reinforcement. I don’t know what the THD number would be, as imo that’s not a problem that needs solving. The in-room frequency response is of vastly greater audible consequence as long as neither woofer nor amp is driven beyond its linear limits.
* * * *
My fascination with subs dates back about twenty-five years, to my simultaneous fascination with Quads and music with bass.
Would like to ask your point of view about time alignment for subs. I run an active system with digital crossovers, time alignment, room correction. I currently have two sealed 12" Rythmiks playing summed up mono and planning to add one or two more to get a distributed bass array.
Time alignment is of great value and active systems are ideal for this. But when it comes to a distributed bass array the sound is arriving at the mic from 3 or 4 different locations so difficult to identify "the max" in the pulse. At the same time Earl Geddes (who also proposes 3 or 4 subs in DBA) and others say we can only hear those frequencies after several cycles have played, so the pulse behavior might not be a good indicator.
What is your point of view about time alignment of a SWARM or other DBA systems?
Dear @atmasphere: The main thread subject is about bass management, so I will answer to you on the tigth regards for last time:
I'm not speculating nothing, I never do. I was very clear that we have ( is a must to. ) to have several experiences in different venues and with different kind of MUSIC in live events seated at near field position and it's from here from came my " speculations ". Rodman, bdp and noble explained very well.
Hi @lewinskih01, you asked, "What is your point of view about time alignment of a SWARM or other DBA systems?"
Imo time alignment is at best a secondary consideration in a distributed multi-sub system, from a perceptual standpoint.
The ear has very poor time-domain resolution at low frequencies, and you are aware of Geddes’ thinking on the subject (which is based on AES papers). On the other hand the ear is very good at hearing loudness differences at low frequencies once the low frequencies become loud enough to be audible. This is why equal-loudness curves bunch up south of 100 Hz. A 5 dB difference at 40 Hz can be perceptually as big a difference as a 10 dB change at 1 kHz! The implication is that getting the in-room frequency response right matters more.
Also, since speakers + room = a minimum phase system at low frequencies, when we fix the frequency domain we have also fixed the time domain, and vice-versa.
That being said, imo you bring up something which intuitively makes sense: Preserving the initial pulse of bass energy, that which "whaps" you. It would seem that precise alignment of the arrival of the energy from multiple subs would best support that initial impulse, but how precise is "precise"? Within 1/4 wavelength? According to a paper I read, the ear cannot even detect the presence of bass energy from less than one wavelength, so the "precision" required might not be as great as our intuition would lead us to believe.
This is just anecdotal, but every time I have reversed the polarity of one of the four subs in a Swarm system, there as been a subjective improvement, despite the fact that the initial pulse has been obviously degraded.
This past October at RMAF an industry veteran manufacturer with decades of experience came into our room and played his reference recording of Fanfare for the Common Man. He said, "that’s what a tympani sounds like." He went on to say that our system (in a normal hotel room) did the best he had yet heard on that recording. We were using two amps and had manipulated the phase of the two left-side subs relative to the two right-side subs.
Now it is theoretically possible to use four time-aligned and equalized channels of amplification and achieve precise time alignment and excellent in-room response smoothness simultaneously, and this would probably be even better. But at the price point I’m working, focusing on room-interaction related issues seems to give good return on investment.
Once we relax cost constraints, it might make more sense to build a planar array into the front wall and a corresponding array into the rear wall, reverse the polarity of the rear wall array, and time-delay it such that it cancels the signal from the front wall when it arrives.
Dear @audiokinesis : "" I didn’t design the Swarm to go below 20 Hz """
of course you did not and certainly not at your market price. I’m not with an attitude to make a critic or something against your product what I’m doing is to post some facts for the people really know where are " seated ".
As you I have more than 25 years with the " fascination " subs ideas because is a true fascination when you are " there ". I’m a simple music lover and audiophile.
The people that own your product could think they are " there " but in reality they are not yet.
The true and complete room/system bass management premise is that the audio system can handled bass frequencies below 20hz at real/live event SPL with lower THD we can achieve in our room/system ( other day we can talk about the importance of that THD. ) and to accomplish that we need self powered true subwoofers and we not necessarily need 4 subs we can do it with two true subs. The Harman white papers proves that. Of course that if we are not satisfied with those two true subs in our room/system then we can go for the 4 solution.
My target is to have the best solution ( rigth now with two true subs. ) at one and only one seat position where the mids and higs are spot on.
There are alot of very valuable music information below 20hz in hundred/thousands of recordings and we can enjoy it in all its splendor if we have the system for reproduce it.
The differences between a quasi-bass management against a true bass management is not little or tiny but higher that what any one of us can imagine. We have to experienced to understand it.
Now all those gentlemans that already has the four not true subs only have to change it for true subs where maybe they will not needs 4 but only 2 but this depends of the room/system, which true subs were choosed and eacvh one of us targets.
I understand the " fascination " that have your customers that are living with and they already think they discovery the bass " panacea " when it’s not that way. They are close to that panacea but needs to " work " to achieve it.
So, my posts were not a true critic or something against to, not at all. Only facts.
Btw, I take a look in your site and I don’t find out which are the 3 +,- db points in those 10" units. Could you share it?. Appreciated.
Only for your records: I bougth my ADS L2030 ( that was not and stritly massive market product because was not designed for consummer market. ) many many years ago and when I was absolutely ig norant about bass management and its importance and with out knew nothing about the Harman papers. I bougth it in Laredo,Tx. because the vendor convince me about and because in those old times we can seen ADS advertasing in all audio magazynes as High Fidelity, Stereo Review or Audio.
Well these sealed/acoustic suspension ADS design between other drivers has two 14" woofers and line source for the mids/higs and its bass specs at 3 +,- db are: 22hz and 18hz at 5+,- db an 16hz +,- 4 db bi-amp fashion using its dedicated active C2000 crossover that I owned and I think still own.
Well, ADS was choosed ( with out knowing for my self any information about this.) by Telarc for monitoring all the Telarc recordings and the first recordings Telarc used ADS speakers designed exclusively for them and powered by Threshold. Latter on Telarc ask to ADS for a better full rage professional monitor and was then when ADS designed the L2030 that was runned in bi-amp fashion with the C2000 and Threshold electronics. The man behind the desin of ADS L2030 speakers was Mr.Kelly whom rigth after this his last ADS speaker design ( he was the engenner in chief in ADS. ) founded the very well regarded Aerial Acoustic that between other things has true subs in its catalog line.
Well, even all those at some time of my audio life all was not enough for me and I started with subs till today where my self heavy up-graded L2030 works as satellite speakers in my room/system.
I post this history because no matters how low the speakers goes if are passive design always will be a huge benefits integrating to those speakers with two true self powered subs.
The subs market development and growing is just starting because from a few years now audiophiles are starting to learn that true subs are not for HT but for a stereo system in our places. So the best on regards is forth coming and this is a very good news for we audiophiles and people like you that are manufacturers and good designers.
@rauliruegas wrote: "we not necessarily need 4 subs we can do it with two true subs. The Harman white papers proves that.... My target is to have the best solution ( rigth now with two true subs. ) at one and only one seat position where the mids and higs are spot on."
You can get good bass in one sweet spot with two equalized subs. If you want good bass over a significantly larger area, four subs intelligently distributed can make a worthwhile improvement.
(Note that Todd Welti et al did not investigate asymmetrical sub placements, and they also made the assumption that rooms are acoustically symmetrical at low frequencies. This totally made sense for the paper they were writing. But in practice rooms are never symmetrical low frequencies because unless the room has no doors or windows or AC vents or other "soft spots" in the room surfaces. Even a heavy recording studio door is a significant "soft spot", changing the room's effective length in that dimension at low frequencies.)
Rauliruegas also said, "Btw, I take a look in your site and I don’t find out which are the 3 +,- db points in those 10" units. Could you share it?. Appreciated."
The response of the individual Swarm units is the approximate inverse of "typical" room gain. "Typical room" gain has been given by several authors as being about 3 dB per octave below 100 Hz or so, so my response curve is -3 dB per octave from about 100 Hz down to about 20 Hz, and then below 20 Hz the rolloff accelerates rapidly.
In other words I look at subs + room as a system, and my target is all about what the system does, not what the part I make does all by itself. The Swarm system is highly adjustable to work well with a wide variety of rooms. Ports can be plugged, polarities reversed and/or phase manipulated, and the amp includes a single band of parametric EQ along with a +3 dB "bass boost" switch. In practice, the output of the four distributed subs combines in semi-random phase at the upper end of the bass region, gradually transitioning to approach in-phase at the bottom end of the bass region as the wavelengths become long relative to the room dimensions. In most cases it is beneficial to offset this additional gain as we go down in frequency by reversing the polarity of one of the subs, or if we are using two amps, by manipulating the phase of one amp relative to the other.
If I were to tell you that my subs are "-3 dB at such-and-such Hz", none of the above information would be conveyed by that spec. Unfortunately people compare subs based on who has the lowest -3 dB spec, and therefore manufacturers compete on the same basis, and what REALLY MATTERS (which is, what happens when you put the sub into a room) is not given much if any consideration.
Dear @audiokinesis : """ You can get good bass in one sweet spot with two equalized subs..."""
and that’s the target of almost any audiophile at his room/system. Makes no sense to me to have several bass seat positions when the mids/hig frequency range has only one seat position and no one audiophile listen only bass range.
I know is your business but not the one for a home audio system audiophiles.
In my case at my place in my room and with my system I don’t need but 2 subs but as you posted: " you can get good bass in one sweet spot with two equalized subs "", that in my case are not equalized at all.
Now I remember what you posted that +,- 3dbs at 100 and 20hz that I read at your site. Thank's.
Excellent description of bass , thank you. I often find it difficult to describe in words what I consider good bass response but I think your information about "critically damped" at a specific system Q factor of 0.7, wich is a good balance of bass quantity vs bass quality, is very descriptive and useful. Sort of like Goldilocks' porridge, just right. I understand that a sub's woofer driver has its own resonant Q, which is modified by the sub enclosure’s resonant Q. These resonances combine and interact to reach the system Q. A Q of less than 1 is considered overdamped, while a Q of more than 1 is underdamped. Most sub designers aim for a Q of about 0.7 to reach a compromise between extended bass response (down only 3dB at resonance) and good transient response (very slight overhang). Some designers maintain that a Q of 0.5 is ideal, and that a higher Q produces bass of poorer quality. I'm not sure of the exact Q factor of each of the Audio Kinesis Debra's 4 subs I use in my system, or if the Q factor of each sub differs from that of all 4 operating in concert. I expect the dba system Q factor would be somewhere in or very near the 0.5-0.7 range since I consider the bass performance to be very well balanced between bass quantity and quality. I think it’s possible to put together an extremely involving music system based on smaller speakers that don’t reproduce bass below about 50Hz. But I know I enjoy music and ht tremendously more with 6x2ft planar-magnetic panels and a 4-sub dba system that seamlessly integrates the high quality midrange/treble/imaging of the panels with the high quality bass of the dba that accurately extends the bass response down to 20 Hz. I've discovered that experiencing even just most of the bottom octave (16-32 Hz) on music and ht is immensely enjoyable mainly because I perceive both as more realistic. I'm not a Bass-Head but I admit I enjoy the bass weight and power that viscerally involves your whole body in the music or ht. But I also believe in setting the crossover frequency as low as possible so the subs only engage when required for accuracy and not for an artificial general system bass boost. I've also discovered that bass quality is vastly more important than bass quantity. A leaner presentation without much extension is preferable to me than lots of bass if that bass is thick, colored, and sluggish. If the bass isn’t well reproduced, I think most would agree we’d rather not hear it at all. The poor bass performance becomes a constant annoyance and a reminder that we’re listening to a reproduction. I've learned that realistic reproduction of the majority of the bottom octave (16Hz–32Hz) doesn't require large woofers in large enclosures, 4 subs with 10" woofers in relatively small enclosures are equally capable. It's also true that a system’s bass presentation affects such seemingly unrelated aspects of the sound as midrange clarity and sound staging. Thickness in the mid bass reduces the midrange’s transparency. A cleaner mid bass not only makes the midrange sound more open, it also lets you hear more clearly into the extremely low frequencies. Moreover, extending a system’s bottom end has the odd effect of increasing soundstage depth and our overall sense of the recorded acoustic, even on music with minimal low-frequency energy.
I believe there are two main reasons to consider a subwoofer. The first is if you like the sound of your main speakers and just want more bass extension, power, and impact. The second is if you want a full-range sound but don’t want the intrusion of large, floor-standing speakers in your living room, although subs with floor-standing speakers can also definitely improve overall system bass response.
Both cases sound simple in theory, but in practice, getting subs to blend with your main speakers is quite a challenge. Although you’ll undoubtedly get more bass, you might not achieve a sound that is seamless and coherent from bottom to top. That is, you might be aware that there’s big cones chugging away, seemingly disconnected from the rest of the music. But the 4 10" cones, chugging away at a more moderate pace and even with all in mono mode, of a dba's subs seem exceptionally well integrated with the rest of the music in my system.
However, I'd suggest choosing subs designed for musical accuracy, not home-theater fireworks. Some subs exist to produce the highest possible sound-pressure-level at the lowest possible frequency for playing back explosions in film soundtracks. Others are crafted by musically sensitive designers with high-end sensibilities. Be sure which kind you prefer and are selecting.
Proper placement of the subs is very important in providing optimum bass smoothness and detail. One of the huge advantages of sub/satellite systems is their ability to position the satellites for best imaging without worrying about the bass response, and then to locate the subs for best integration and bass response with the room and satellites. This includes treating full-range floor standers as satellites, too.
It's critical to spend some time adjusting the subs’s or dba's amp controls so that it blends seamlessly with your main speakers. On the one hand, getting two different products (the main speakers and subs), designed by two different designers, to work together in harmony is asking a lot. On the other hand, you have much more control over subs or a dba system than you do over the bass output in a full-range system.
Take advantage of the subs’s or dba amp's volume, phase, crossover frequency, and other adjustments to perfectly dial it into your system. Generally, the lower the crossover frequency between the subs and main speakers the better; the main loudspeaker’s bass is often of higher quality than the sub’s, and a low crossover frequency moves any crossover discontinuity lower in frequency, where it will be less audible. In addition, a low crossover frequency ensures that you won’t be able to locate the sound source of the low bass.
Subs reproducing frequencies above 100Hz can be “localized”—i.e., the location of the source of the bass can be detected—which is musically distracting. Too low a crossover frequency will, however, burden small loudspeakers with excessive bass and reduce the system’s power handling and maximum listening level.
Another variable in sub crossovers is the slope. Most use second-order (12dB/octave) or higher filters. Ideally, the crossover frequency and slope would be tailored to the particular loudspeakers used with the subs. But because the sub manufacturers don’t know which loudspeakers will be used with the subs, these parameters are compromised for good performance with a variety of loudspeakers.
A sub’s or dba amp's phase control allows you to time-align the subwoofer’s wavefront with that of the main speakers. Here’s a simple trick for perfectly setting this adjustment. (This technique assumes that the phase control is a continuously variable knob, not just a simple “0/180°” switch.) Drive the system with a pure tone at exactly the crossover frequency between the subs and main speakers. (Many test CDs include a full range of test tones.)
Driving the system with a pure tone at the crossover frequency causes the main loudspeakers and the subs to reproduce the same signal. Now invert the polarity of the main loudspeakers relative to the subs by reversing the red and black leads going to both loudspeakers. Sit in the listening chair and have an assistant slowly vary the phase control until you hear the least bass. Return the loudspeaker leads to their former (correct) polarity. The phase control is now set optimally.
Here’s why: When the main loudspeakers’ and subs’s wavefronts are 180° out of phase with each other, the greatest cancellation (the least sound heard) will occur. That’s because as the subs’s cone moves outward, the main speakers’ cones are moving in, canceling each other. When the loudspeaker leads are returned to the correct position (removing the 180° phase shift), the subs and loudspeaker outputs are maximally in-phase. Any time lag between the main speakers and subs has been eliminated. This technique works because it’s much easier to hear the point of maximum cancellation than the point of maximum reinforcement.
Most subs use either a sealed enclosure or a ported enclosure. Which type you choose will affect the character of the bass the sub produces. In a sealed enclosure, also called acoustic-suspension loading in some designs, the air inside the cabinet acts as a spring behind the woofer, compressing when the woofer moves in. In a ported enclosure, also called bass-reflex loading, the woofer’s rear wave is channeled outside the cabinet by a port or duct. Bass-reflex loaded system maintains flat bass response down to a lower frequency, but then the bass output drops off more quickly than it does in a sealed system.
The common way of specifying a speaker’s low-frequency extension is to cite the frequency at which its response is attenuated by 3dB (“-3dB at 28Hz” for example). This method unfairly favors reflex loading because it doesn’t take into account the very steep roll-off below the -3dB cut-off frequency. The ideal method of specifying a loudspeaker’s bass extension is to cite the frequency in which its response is rolled off by 3dB as well as the frequency at which its response is rolled off by 10dB. A loudspeaker’s -10dB point is a more reliable indicator of a loudspeaker’s subjective bass fullness and extension because it takes into account not only the low-frequency cut-off point, but also the steepness of the roll-off.
There’s one more technical difference between sealed and ported enclosures to know about- transient performance. A woofer in a sealed enclosure, when subject to a transient signal such as a kick drum, will tend to stop moving immediately after the transient. Conversely, a woofer in a vented enclosure could tend to keep moving after the drive signal has stopped. The speaker with the sealed enclosure generally has more accurate dynamic performance.
The AK Debra dba system has removable port plugs that allow the choice of configuring them as either sealed/acoustic suspension or ported/bass-reflex subs. I've tried them in both configurations in my room/system and determined that I perceived both as equally dynamic on transients but preferred the ported configuration since the bass extension seemed superior.
I have the crossover frequency on the sub amp set at 45 Hz, the volume set slightly under halfway and the phase control set in-phase at "0".
My main Magnepan 2.7QRs are operated as full-range and I utilize no bass room treatments and no room correction, other than configuring my mains as 'Large' and my center and surrounds as 'Small' for ht.
Sorry, I tend to err on the side of TMI on my posts,
audiokinesis: "Once we relax cost constraints, it might make more sense to build a planar array into the front wall and a corresponding array into the rear wall, reverse the polarity of the rear wall array, and time-delay it such that it cancels the signal from the front wall when it arrives."
Hello Duke,
I always enjoy your posts because I always seem to learn something.
But my main reason for posting is to ask about your quote above. Was " and time-delay it such that it cancels the signal from the front wall when it arrives." accurate and not a typo? My rudimentary knowledge of bass room acoustics leads me to believe that equal bass sound waves from the front and rear would cause a standing wave room mode at the point that both waves meet, causing a bass cancellation resulting in a perception of no bass at all at that room location. Does the time delay or the polarity reversal on the rear planar array alter the dynamics? Please explain if you don’t mind.
Dear @noble100 : """
I've learned that realistic reproduction of the majority of the bottom octave (16Hz–32Hz) doesn't require large woofers in large enclosures, 4 subs with 10" woofers """
well with the ones design you owns you phisically can't achieve that octave ( 16hz-32hz. ) but from 20hz up. A small driver as 10" with that " motor " can't do it at over 110 SPL and with low THD. Yes maybe some one could design a true sub with 10" woofers but this is other subject, yours can't do it.
"""
I'm not a Bass-Head but I admit ..... "",
me neither.
"" But I also believe in setting the crossover frequency as low as possible so the subs only engage when required for accuracy and not for an artificial general system bass boost. """
well in my case as low as 78hz.
"" I've also discovered that bass quality is vastly more important than bass quantity. ""
Always in agreement with but my main discovering using true self powered subs was the IMPACT that MUSIC we are listening makes when the IMD distortion kind goes way lower in the main speakers: mids/high ranges really shines with. As a very important side benefit is the quality level we accomplish in the overall system bass management.
We have to remember that the MUSIC foundation and MUSIC frame belongs/lives in the bass frequency range and its quality levels.
Not for you but for other gentlemans this link could help to understand better the overall bass management:
Dear @rodman99999 : I own both Virgil Fox LP volume's ( if I remember: white vinyl. I don't listen it for several years now. ) and just great if you have the system that can showed.
One recording with true subterrean bass range is the Dorian CD with the transcription scores of Pictures at an Exibition by Jean Guilllou. Always not only very good score quality performance but a true test for any system especially in the bass range.
I own too an LP ( I can't remember the label. ) with the Mormom Tabernacle Choir that I remember wa really good recording.
As a fact and as I posted there are " thousands " of recordings with true low bass range and with very good overall quality performance.
Other labels that comes to my mind is Wilson Audio, Athena, Denon, Delos, Chalfont that along Cristal Clear several more are a must to listen it.
Is just grandioso/magnificent that we truly can appreciated in all its grandiosity all those " historic "recordings. Good that some of us can do it.
First I read anything from the doctor. I don't think the Sound Doctor is a good source of info for newbies. He goes on about bass standing waves, bass room modes, and bass sound wave timing as if he's not even aware of the scientific research and writings of Geddes, O'toole, Welti, Lejeune, etc. and that most of the in-room bass response issues he mentions can be solved through the use of a 4-sub distributed bass array system. I'm not sure if he's aware of the dba concept and how well it works or not. I wonder where the good Doctor got his degree from? Do you think he just bought one on the internet? It seems like he's the one in need of some bass management education.
@noble100 wrote: "But my main reason for posting is to ask about your quote above. Was " and time-delay it such that it cancels the signal from the front wall when it arrives." accurate and not a typo?"
That’s what I meant to write.
My understanding is that the idea is to arrange four subs in a centered, half-the wall’s-scale pattern on the front wall. So if the front wall is 18 feet wide by 8 feet tall, then the subs would be at the corners of a rectangle 9 feet wide by 4 feet tall, centered on the middle of the wall. This mimics the best four-sub geometry Todd Welt found in his study of symmetrical sub arrays, but it’s on the wall instead of on the floor. If the wall reflections cooperate, they should cancel out standing waves in the vertical and side-to-side dimensions.
To cancel out standing waves in the front-to-back dimension, the idea is to use active cancellation based on an identical array on the rear wall. This array is in reverse polarity, with a time delay that corresponds to the length of the room.
So the subs in the front of the room to create a planar wave that moves to the back of the room and then disappears as the active cancellation array cancels it when it gets to the back wall. The "no bass" you mentioned happens at the rear wall, not out in the room, or so the theory goes.
I do not know how well this would work in practice. The answer is probably some variation on "it depends". Nor do I know whether it would sound better than a distributed multi-sub system. I haven’t really investigated it and will never build anything like it myself, but it MIGHT be a competitive "cost no object" approach.
A number of years back, Danny Richie's GR Research system was voted as producing "Best Bass At The Show" by attendants of the RMAF show. Danny used a pair of Rythmik/GR Research OB/Dipole Subs at the front of the room, and a pair of Rythmik F12G Sealed Subs at the rear, their phase controls set 180 degrees opposed to the front subs.
audiokinesis: "The "no bass" you mentioned happens at the rear wall, not out in the room, or so the theory goes."
Hey Duke,
Okay, that makes a lot more sense to me now. When I win the lottery, I'll buy a pair of Magnepan 20.7s and some extra bass panels, build a room and give you a call to try it out.
I'll be living right on the beach somewhere. Thanks, Tim
Dear @noble100 : The Sounddoctor is a point of view as can be yours, Audiokinesis or any one else and there is no reason that we can read it and the ones with more knowledge levels in the bass regards will took what is " rigth " and diminish what's wrong.
From some time now, I try to read the more I can on that regards.
When I started I did it alone with out knowing Harman or Geddes papers I just trust is what my nearfield live music experiences told me. Yes I took more time to achieve that " there " mentioned before that's what must be an audiophile target.
I have two true subs in a room with out bass traps and no equalization of any kind and I'm lucky enough to stay " there ". You are closer to that " there " so go for it, makes a difference and you will know when you experienced in your room/system.
Btw, I'm in this thread and in the other bass thread because I'm learning from almost every one.
I think that other than the Harman white papers no one is owner of the " bass Bible ". I know that reading " here and there " and following making some additional tests or making very little position changes or the like we can learn and perhaps a new kind of improvement. Well this is the way I think and the way I'm moving in my room/system, overall not only in the bass management. My main target is to stay nearer to the recording.
I just consider myself a student of good home audio, too. Over the last decade or so, I've mainly been on a quest for good home audio bass response. Through experimentation and research, I've found some methods for achieving good bass response and integration in my room and system, just as it seems you have. I think we're both just sharing what we've learned with others. Nothing wrong with that and I wish you only the best on your quest to stay nearer to the recording.
Hey Noble, Real Bad Idea. I love Maggie 20.7s but adding two more bass panels is just going to give you a lot more of no bass.(below 40 Hz) Dipoles make crappy subwoofers. There is this myth out there that you can not mate a dynamic sub with a dipole bas panel. That is because most are trying to do it the wrong way based on more mythology. I have been using dipoles exclusively since 1976. I would never live with out a sub woofer. There is no other way to reproduce that visceral you are there experience.
Nice thread everyone. Sorry my work is crazy so I don’t check the site as often as I would like. Just had my daughter graduate college yesterday and she did it in three years with a foreign exchange in Japan. Pretty excited about that and the fact she has an second interview with a Fortune 500 company Tues in New York, fingers crossed!!
Here are responses to your questions below Tim and a few notes about setting up my system with Magnepan 20.1 mains.
hifidream,
I forgot to ask a few questions about your custom dba system in my previous post. I hope you don't mind, I'm just curious about a few things:
1. What brand and model were the initial subs: - Kinergetics SW-800 subs (next to my 20.1’s - five 10” Seas subwoofers in their own non-ported enclosures) driven by a Pass X-250. I researched a ton and wish there were some threads like this when I was planning my system. I looked for five years before finding the Kinergetics online used. I bought them and owned them for another four years before I could play them.
2. What brand and model were the last 2 subs you added to your system? - SVS SB-16 Ultra subs (2 enclosed mosfet powered subs). Funny story, I turned them on low without optimizing them and played the music from the Gladiator and the water on my table rippled, house creaked, I jumped out of my couch because my gut wrenched, and my wife leapt out of the shower telling me to unplug the system as thunder just shook the house! Ergo too much base :)
3. Do you operate your 20.1s full-range or limit their bass output? - I operate them full range. I don’t want to loose all that beautiful sound.
4. What upper cutoff frequency are your subs set at? Simple answer around 80Hz at the highest. Each of my 8 channels has 12 biquad active filters created by Multi Sub Optimizer (MSO) inputted into my Mini DSP working at 24/96, details below. - In order to maximize the accuracy by eliminating room nodes, and best integrate with the 20.1s I measured the speakers individually with Room EQ Wizard (REW) and the room from my listening position with my Earthworks microphone. I used all the data and followed the instruction manual in MSO plugging in my data and adding more filters as I started to understand how it works and listening to the results. MSO suggests running the subs full range and I was surprised how high they actually ended up crossing over to counter room nodes outside of the subwoofer region.
So I’ve listened to my 20.1s without subs and while big and dynamic they didn’t give me what I heard when I played in an orchestra. Added the Kinergetics and the sound was close but standing waves were messing with the room (it was a small place). We moved into a nice big apartment and I got the SVS hooked up and did my room correction and all I can say is OMG. It’s the closest thing to my live playing experience I’ve ever heard.
Yes there is sound in those very low octaves, organ notes, tympani, and the low rumble of the orchestra in full swing. You can feel it in your body. . . (I could hear most of the music in my 20.1s but not feel it). No one listening to my system can articulate there is one subwoofer much less 4 of them or 6 if you count the Maggie’s. They integrate perfectly and seamlessly. It’s not about loudness but accuracy and I agree with many who have spoken to poor base integration ruining their set up. The one comment I get when people come hear my set up is how “clear” it is. This is the sign that everything has been set up correctly. It’s not an easy thing but the reward is awesome.
I do bump up the subs 5db for movies and the last time I had my dad and daughter’s boyfriend over for an action movie they jumped out of their seats on an explosion and move their heads out of the way when there are gun shots (they didn’t even know they were doing it because they were so into the movie.) . . . The anamorphic 11x5ft 4K image helps too. It’s a lot of fun.
Dear @noble100 : As you I continue in the quest and each " day " nearer to.
Now and for the low bass stereo or mono. How was recorded stereo or mono?:
after some days of hard work and a lot learning sessions listening to CDs containing true low bass, at least to 16hz and even lower that that, as these CDs recorded in different times from early 80’s to today days. I listen it mainly Motion Picture Original Soundtracks ( lovely !. ):
Telarc 1812, Casper, Black Hawk Down, Vangelis 1492, M:1-2 ( Mission Imposible. ), Gladiator ( second recording where the titles does not appeared in the Picture, was part of the Zimmer overall takes before decided which use it for. ), Glory, The Thin Red Line, Blade Runner ( first picture. Vangelis. ), The day After Tomorrow, Interstellar and Alita.
The low bass comes recorded in MONO as you posted in the other thread but now I’m totally sure about.
Even that still is one point that I would like to have clear and is if the low bass information is recorded mono from 50hz or 40hz or 30 hz down these frequencies. I ask my self which is the bass frequency range recorded in MONO and from where starts to recorded Stereo ?. I don’t know, yet.
I listening to those CDs first whith all my system playing in stereo and mono fashion, then single channel in stereo and mono fashion, after those I started to listen only to the information coming from the subs and when I try to find out that bass frequency range recorded ( from-to. ) is impossible to find out by listening it because the very low bass dominates the subs response and ( at least me. ) can’t distingish any thing about.
Anyway, my test experiences were to confirm or not what you posted and you are rigth: MONO is the way is recorded and those CDs producers/engineers are loosing out on the opportunity to make the CD recording with the bass information that the microphones pick up at the recording sessions.
Seems to me that because the recording of LP’s during the cutting proccess the bass information must goes in MONO due to the analog/LP limitations the producers/engeneers accustom to never think to make CD recordings taking advantage of the digital alternative that has no limitations about ! ! ? ? ? ? Maybe exist something in those very low bass information that the microphones pick-up that could or can makes useles doing it in Stereo fashion, who knows?
Well I hope that some one there can do it in the near future or at least try it/test it and decide about.
Seems to me that because the recording of LP’s during the cutting
proccess the bass information must goes in MONO due to the analog/LP
limitations the producers/engeneers accustom to never think to make CD
recordings taking advantage of the digital alternative that has no
limitations about ! ! ? ? ? ? Maybe exist something in those very low
bass information that the microphones pick-up that could or can makes
useles doing it in Stereo fashion, who knows?
Its not so much the limitations of the format as it costs a lot of money to pay an engineer to work a way around "out of phase bass". If you spend the time with the recording, you can usually find a way to master it without having to process it. But that takes time and at $500/hour most often bass processing is used. This is a simple circuit that senses when bass is out of phase and makes it mono below about 80Hz for a few milliseconds until the event has passed. This makes mastering LPs less expensive!
But CDs do exist where out of phase bass exists. This can happen because a microphone is out of phase with the rest of the recording when a bass guitar or bass drum is recorded. For this reason, the recording engineer has a phase inversion switch on every channel of his mixer but he may not have thought to use them.
If the recording is done in its entirety with only two mics, out of phase bass will not exist.
Dear @atmasphere : What I really mean was not a LP limitation perse but an analog rig limitation because cartridges just can't track with applomb very low bass grooves.
Telarc 1812 is a good example where I own over 120+ cartridges and only a few can track those cannon shots with clean and pristine true applomb. Between other things cartridge self abilities is always a limitation and not only at very low bass.
"""
For this reason, the recording engineer has a phase inversion switch on every channel of his mixer but he may not have thought to use them. """
So, recording engineers do not really care about and even to check the microphones phase in between.
What I really mean was not a LP limitation perse but an analog rig
limitation because cartridges just can't track with applomb very low
bass grooves.
Telarc 1812 is a good example where I own over 120+
cartridges and only a few can track those cannon shots with clean and
pristine true applomb. Between other things cartridge self abilities is always a limitation and not only at very low bass.
@rauliruegas More depends on the tone arm's ability to track the cartridge than it does on the cartridge itself. Its a good bet that when they cut that track they played it on a very ordinary turntable to make sure it was playable.
Dear @atmasphere : All cartridges has its own tracking abilities determined not only for its compliance level but the tip mass, cartridge weigth and ceratinly how good is matched with its couple tonearm ( resonance frequency in between. ) but today tonearm that are well damped and even not very good damped but with good bearing design does a good work about. Of course that the TT platfform has something to says: if good damped or not so good, speakers sound vibrations and overall room vibrations. Analog rig is very complex to achieve a " perfect " job.
Ok, for my part is all on these regards because the main bass thread subject is different.
mijostyn: "Hey Noble, Real Bad Idea. I love Maggie 20.7s but adding two more bass panels is just going to give you a lot more of no bass.(below 40 Hz) Dipoles make crappy subwoofers. There is this myth out there that you can not mate a dynamic sub with a dipole bass panel. That is because most are trying to do it the wrong way based on more mythology. I have been using dipoles exclusively since 1976. I would never live with out a sub woofer. There is no other way to reproduce that visceral you are there experience."
Hello mijostyn,
I currently agree with what you posted. I think we both know for certain it's possible to seamlessly integrate powerful dynamic subs with dipole panels because we've both done it in our own systems, in our own rooms and with our own dipoles. We both know how to do it well, although in somewhat different methods.
You're also likely correct that dipoles make poor subwoofers. But my response, to trying Duke's concept on dipole sub arrays built into the front and rear walls, was hypothetical and prefaced on me winning the lottery. Meaning I'd have the disposable income to give it a try. If it didn't perform better than my current dba, I'd probably just use a custom dba with 4 dynamic subs that could each reproduce bass accurately well below 20 Hz. I do enjoy visceral bass in music and ht.
Nice to hear of your daughter's successes. I wish her the best.
Thank you for taking the time to respond to my previous post. You have assembled a very impressive custom dba system with very high quality Magnepan 20.1 main speakers. It seems like you've taken the excellent dba concept to new heights of performance through the use of 2 Kinergistics tower subs, 2 SVS SB-16 Ultra subs, the Multi-sub Optomizer, the Mini DSP along with the dual dipole bass panels in each of your 20.1s. From personal experience, I know it's somewhat difficult to integrate the bass reproduced by dynamic subs with the fast, smooth and detailed top to bottom sound reproduced by panel main speakers. I understand the pleasure of having guests jump out of their seats from powerful and dynamic bass on both music and ht. The ability of dbas to provide excellent bass response throughout the entire room, and not just at a single sweet spot, is the result of eliminating the perception of bass modes in the room. This not only has the benefit of startling guests but also has the added benefits of increasing the sense of imaging depth, the details within the deep bass and better clarity from mid-bass to treble at the listening sweet spot.
Noble, if they are built into walls they are no longer dipoles and trying to get the resonances out of walls is a nightmare. The limiting factor in all Maggies with a ribbon tweeter is the tweeter. It is a wonderful tweeter, some say the best ever made but it is delicate. Adding more panels is not going to increase the system overall output. I can't speak about sound quality because I have never heard it done. Quality first, output second. The key with any linear array system is to keep it functioning as a linear array over the entire audio and subsonic spectrum so that power output remains even from top to bottom. There is always a weak link in the chain. In my case even with 800 class A watts at my disposal it is the satellite amplifiers. At that point I am putting out 110 db which from most peoples stand point is absurd. Comfortably loud is 95 db. At 110 db my subs are hardly working. You have to make your subs a linear array which you can do either vertically with two sub towers from floor all the way to the ceiling or horizontally with drivers all along the front wall from corner to corner. It is easier to control resonance in a smaller enclosure so I favor multiple small cabinets over one or two large ones. Your explanation of Q was excellent. I build my subs with a higher Q than usual 0.76. I depend on amplifiers with very high damping factors to control the drivers. This increases efficiency. How many you need depends on the length of your wall and the crossover frequency you want to use. To take the most advantage of boundary gain two have to be in corners and the others along the floor wall boundary. I use a cross over of 125 Hz so the individual drivers have to be 6 feet or closer together. The wall is 16 feet so a total of four subs will do the trick. Because of boundary efficiency with room control I am flat down to 16 Hz where I roll the party off steeply to prevent issues with the turntable. If you want to use a higher crossover you have to space the drivers closer together. If you have a longer wall you will need more drivers. A point source system is different. If you used this type of sub array with a point source system as you backed away from the speakers the subs would become overpowering. As Atmasphere suggested a two sub system tuned to the listening position would work fine or if you wanted more even response throughout the room a "Swarm" would be fine. I use 12 inch drivers exclusively by the way. I am working on a new set of balanced force subs with octagonal enclosures made of 2" MDF. They are essentially a tube with a 12" driver in each end opposing each other, canceling out all Newtonian forces. Same Q.
Very good and interesting information, thank you. I'm very satisfied with the bass response in my room with the AK Debra 4-sub dba system, even though it's only capable of flat bass down to 20 Hz. If I ever wished to extend the bass response down to 16 Hz, I know my best solution would be upgrading all 4 subs to ones capable of reproducing bass down to 16 Hz. I know my current bass system, with flat frequency response from 20-100 Hz, can only reproduce the majority of the entire lowest octave (16-32 Hz), but I'm currently satisfied with that since I currently play no source material with bass content below 20 Hz that I'm aware of. My system goal is to reproduce bass that is accurate, detailed, dynamic, powerful and sufficiently extended to reproduce the lowest frequencies contained on any source content I choose to play. While I believe my current source material (Redbook cds, streaming services and 24 bit/96 Khz FLAC digital files) are limited to a deep bass frequency of 20 Hz in mono mode for various reasons, I realize Redbook cds and direct to digital hi-rez recordings are capable of capturing discrete L/R channel bass channel content at even deeper bass frequencies. This would allow true stereo bass playback on recordings. Just to be clear, the walls of dipole subs front and back is audiokinesis/Duke's idea that he's never actually tried. I believe it's best if he replies to your specific points about his concept. I told him I'd pay for him to build me one in my new home if I won the lottery, which is not likely to happen since I don't normally even buy any lottery tickets. So, it's all currently hypothetical.
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