Hello 2pyop, I think a better question is why would anyone expect 2 full-range floor standing speakers, no matter their quality or price, to be able to provide both good bass response and good midrange/treble response at a designated listening seat when the low frequency sections of the speakers are not able to be independently positioned in the room. This makes as little sense to me as the use of subs apparently does to you. It’s well known that bass soundwaves behave very differently in any given room than midrange/treble soundwaves will behave in the same room, mainly due to physics. The frequency of soundwaves are directly related to their length, the lower the frequency the longer the sound wave. This equates to a 20 Hz deep bass soundwave being 56 feet long and a 20,000 Hz treble soundwave being .056 inches long. Humans are very adept at determining the originating location of midrange/treble frequencies but very poor at determining the originating location of bass frequencies at or below about 80 Hz. In other words, midrange/treble frequencies are very directional and deep bass frequencies are not. All soundwaves, once launched, continue to move forward and bounce or reflect off any room boundaries (floor, ceiling, walls) they encounter along the way until they run out of energy. This regularly results in direct and reflected soundwaves meeting/colliding which causes frequencies to be perceived at these spots (called room modes) in the room to be exaggerated, attenuated or even cancelled. Midrange/treble room modes are generally perceived as a sense of ’airiness’ and ’liveliness’ and the modes can be significantly reduced in any room via room treatment panels. Bass room modes are generally perceived as a sense that the bass is not smooth and natural and the modes can only be reduced, according to traditional thinking, via expensive and large bass trap room treatments. There is another proven alternative method, however, that takes a very different approach called a distributed bass array (dba) that utilizes the principles of psycho acoustics to provide excellent perceived bass response throughout the entire room, not just at a single dedicated sweet spot. These complete dba systems can be purchased for $2,800 from Audio Kinesis as either the Swarm or Debra system. The main difference being the Swarm subs are a bit shorter and wider than the Debra subs. Both systems include four 4 ohm subs with 10" aluminum long-throw drivers and a single class AB 1K watt amp that drives all 4 subs. The subs are strategically distributed within the room and their purpose is to create many bass modes (peaks, dips and nulls) in the room with the knowledge that our brains will process these numerous varying modes by averaging them out. I’ve used the AK Debra dba system for about 4 years now. This concept works like a charm and provides bass that is very accurate, natural, detailed and smooth throughout my entire 23 x 16 x 8 foot room. It provides what I consider sota bass performance that is able to reproduce whatever bass the content calls for; rhythmic, taut and detailed bass for music as well as sudden, deep and powerful bass for ht and music. Here’s a review from the Absolute Sound on the A K Swarm system: www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/Tim |
Since bass sound waves behave so differently in any room versus midrange/treble sound waves in the same room and good bass performance is more difficult to achieve in any room versus midrange/treble performance in the same room, I'd suggest it makes sense to consider our system as 2 systems,a bass system and a midrange/treble system, and it's logical to deploy and optimize the bass system prior to deploying and optimizing the midrange/treble system.
Starting from scratch, the best method for deploying and optimizing bass performance in any room that I'm aware of is a 4-sub distributed bass array system.
For those already owning high quality full range floor standing speakers that are capable of outputting accurate deep bass down to at least 20 Hz, however, I believe it may be the exception to the general strategy of getting the bass performance optimized first. This is because these types of high quality speakers are unique since each speaker, in effect, already contains a high quality sub due to the exceptionally good deep bass extension of each speaker's bass section.
In these scenarios, I would suggest first positioning the floor standing speakers to optimize the midrange/treble response as well as the stereo imaging at the dedicated listening seat. Once this is done, the positions of the first 2 'subs' in your custom 4-sub dba system are established. From here, it's just a matter of buying 2 more subs and positioning them in the room so that bass response is optimized at the dedicated listening seat. I even believe the 2 additional subs don't need to be of the same quality level or size of the main speakers' bass sections for the dba concept to work effectively.
This method is a bit of a compromise from a complete Swarm type dba system but I believe it will provide very similar results. I believe this because the main dynamics involved in the very effective dba concept would still exist; 4 asymmetrically positioned subs with each creating bass room modes. At the listening seat, the brain processes the multiple room bass modes (bass peaks and dips) by summing and averaging them which results in the bass being almost magically perceived as detailed, natural and smooth.
Voila, psycho acoustic principles at work. The dba concept absolutely produces the best bass performance I've ever had in my room and system. I was initially very skeptical and I know just my words will likely convince very few but I also know even a brief demo would convince everyone.
Tim
|
kink56,
The real strength of a 4-sub distributed bass array system is with musical content. There are 4 subs with 10" drivers strategically positioned around the room, driven by an abundance of power with the sole responsibility of reproducing bass frequencies between 20 Hz and whatever the crossover frequency is set at.
The result is very fast bass which is very smooth, detailed and agile. There's also the added benefit of very good bass dynamics due to the ample power reserves.
Prior to using the AK Debra dba system, I was unable to seamlessly integrate very good deep bass response with my fast Magnepan 2.7QR dipole panels with either a single or dual subs. I perceived that bass as a bit lagging and disconnected. I believe the nature of the bass produced by good dba systems will allow them to be seamlessly integrated with virtually any pair of main speakers.
The fact that 4-sub dba systems are also excellent for ht use is just icing on the cake.
Tim
|
Hello hifidream,
Congratulations on creating your own custom distributed bass array system for your Magnepan20.1 speakers. I know the 20.1s have very good bass performance in stock form with 2 large planar-magnetic bass panels in each speaker that all output down to 25 Hz. Not full extension to 20 Hz like many good subs but close and very respectable.
Counting each pair of bass panels as a sub, I would suggest you're actually using a total of 6 subs in your room/system. While 2 aren't outputting bass that's fully extended, they're both outputting the exceptionally fast, articulate and smooth bass provided by planar-magnetic panels down to a deep bass level of 25 Hz.
Since we've both experienced the amazing seamless integration with even fast planar-magnetic panel speakers (whether mid-level models like mine or top of the line models like yours) and the high quality bass produced using 4-sub dba systems, I think it's safe to assume you'd agree that the dba concept works exceptionally well.
Tim
|
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 2 subs you added to your system?
2. What brand and model were the last 2 subs you added to your system?
3. Do you operate your 20.1s full-range or limit their bass output?
4. What upper cutoff frequency are your subs set at?
Thanks,
Tim
|
mitch2,
It was mentioned earlier that humans are unable to perceive true stereo in the bass frequencies below about 80 Hz. Even if you were an exception, there's the problem that there's virtually zero musical content recorded with discrete L/R bass signals. I'm aware of none in cd or lp format.
I run my 4 subs in mono mode because of this. As I've stated before, however, I do perceive the bass as stereo in my system on well recorded cds and 24 bit/96 Khz FLAC files even though I believe the bass is summed into a mono signal. By stereo bass, I mean I perceive the bass as originating from the proper position within the sound stage illusion. For example, the kick drum dead center and the upright bass a few feet forward and a few feet left of the kick drum.
I can only explain this by assuming that the higher harmonics or overtones of the deep bass fundamental notes's frequencies extend beyond 80 Hz and are being reproduced by my main speakers, giving my brain the clues it requires to associate the higher directional harmonic frequencies with the much deeper and non-directional fundamental frequencies reproduced by my bass system and determine the specific locations of the bass instruments.
In your situation, since there are no recordings with discrete L/R bass channels, locating a sub in the middle of your back wall and running them all in mono would give you smoother bass that you'll perceive as stereo bass. Adding 2 more subs, running all 4 subs in mono and positioning them where they sound the best to you will provide the smoothest, most natural, most dynamic and effortless bass that you'll perceive as stereo bass. I'm almost certain it'll provide the best bass response you've ever experienced and it will provide sota bass response throughout your entire room, not just at a single sweet spot.
I can share a best practices method to optimally locate each of your 4 subs if you're interested.
Tim |
clio09,
I can only tell you what my definition of 'tight' bass is, which I realize may be a term that has different subjective meanings to others. A bit difficult to describe but easy to identify when you hear it.
Tight bass to me means accurate, solid and natural bass. The leading edges, the pitch and tone, the duration of the sound, the volume, the impact and the decay of the bass all are perceived as accurate and natural. There's also no sense of exaggeration, attenuation, blurring or something added to or missing from the bass. In other words, the sound of bass instruments sound right and tight, just as they sound when played well and heard live in person.
I've also personally noticed that, if the musicians get too drunk, then you often don't get that proper degree of funk.
Tim |
rauliruegas,
I don’t understand why you’ve been going after atmasphere/Ralph, either. Yes, his primary business is designing and selling high quality tube gear but it’s a mistake to assume his audio knowledge and experience is limited because of this.
I’ve been reading his posts for years and it’s obvious he has an abundance of knowledge on a wide range of audio subjects that I’m sometimes surprised by. For example, he knows Duke Lejeune, owner of Audio Kinesis that sells the Swarm and Debra 4-sub distributed bass array systems, and is well versed on the subject of attaining good bass response in rooms smaller than recital halls.
He’s been setting up very good sounding systems in small audio show rooms for years, often utilizing subs and dbas to get the bass sounding right in these rooms which is almost always very difficult to do.
His personal system speakers are capable of very good deep bass output down to 20 Hz but he’s still adding a couple of custom subs because he already knows through experience that this is the best method to further smooth and improve bass response in his entire room.
I’ve explained the above because it appears from a few of your posts that you’re unaware of Ralph’s breadth of knowledge and experience and the value many Audiogon members, including myself, place upon the information, opinions and advice he shares on a consistent basis.
Thanks,
Tim |
pwhinson: "
I have to admit that with my Magnepan 20.7's I have toyed with the idea of adding a subwoofer but in the case of the 20.7's in my room they measure flat down to about 28hz and only then start to roll off. So I would not want to crossover the signal "from" the maggies to a sub, rather I would want to blend a sub in beginning at around that point of 28hz. BUT of course there's just very little music down there I don't believe however." Hello pwhinson, I've only listened to the Magnepan 20.7s once (driven by either Boulder or Bryston amps at Audio Connections near Chicago) but still know I'd definitely already own a pair if I was only richer. I remember the sound as the usual great Magnepan midrange, treble and imaging of their top model combined with a much deeper bass response than I was expecting. It was not only well extended deep bass but incredibly high quality bass that was just as fast,smooth and highly articulate as the midrange and treble response, resulting in a seamless quality to the sound from top to bottom that was very impressive. You're correct that there's not a lot of musical content requiring reproduction of frequencies much below the 20.7's bottom limit of 25-28 Hz. I'd only suggest adding subs to your system if any of the following is important to you: 1. A system that's completely capable of reproducing all humanly audible frequencies from 20 to 20,000 Hz. While it's true that there are few recordings with deep bass down to 20 Hz, and if it exists it's probably summed L/R ch mono bass, there are some that do contain bass this deep (but not none on vinyl) and you'll only know it's there if your system is capable of reproducing it. There's also the possibility that new physical or downloaded music formats are introduced that allow for full range (20-20K Hz) recording and playback. I have no advanced knowledge of any new formats but even some existing formats (like cds, blurays and hi-res digital files) are currently capable of full audible range recording and playback. It may also be useful to consider the types of music you listen to. I believe only pipe organs, classical, some rock/jazz and electronica contain notes this deep. 2. A system that is currently used for both music and home theater or you're considering using it for ht use in the near future. There's an abundance of sound effects and even some music that has very deep bass content on ht content like regular and 4K bluray discs as well as many premium channels on subscription HDTV services. If either of the above is important to you, I believe adding subwoofers to your system would be beneficial. I think you have 2 options if you're interested in extending and improving the already very good bass performance of your 20.7s. One option is to add 2 good powered subs of your choice and experiment with their positions in your room as well as the volume, crossover frequency and phase control settings on the subs until the bass sounds best to you (smoothest, most natural and most seamless integration with the 20.7s). I suggest you use 2 subs, rather than a single sub, because 2 will provide faster and more agile bass that more closely resembles the bass supplied by your 20.7s as well as better smoothing and adding impact to the overall bass response in your room. I would also advise you to calibrate the best bass response for music because, in my experience, this will also work well for ht use, too. Of course, the brand and model of the subs is your choice but I'll recommend a few that I think might work well in your system and room: JL Audio F110- 10" long-throw aluminum driver, 1,200 w amp in a sealed enclosure, 13.5"W x 14.24"H x 16.51"D and 52.7 lbs., about $1,500 ea. REL T9i- 10"
long-throw aluminum driver, 300 w amp in a sealed enclosure, 13"W x 15.2"H x 16"D and 41.3 lbs., about $1,300 ea.
SVS SB1000- 12" fiber composite driver, 300 w amp in a sealed enclosure,
13"W x 13.5"H x 14"D and 27 lbs., about $500 ea.
I'm fairly certain the addition of 2 subs, properly positioned and configured, would prove to be a good improvement to your system's overall bass response for both music or ht. The major downside to this approach is that it would only extend your deep bass response to about 24-25 Hz. You would clearly perceive a smoothing to the bass and additional bass impact but, unfortunately, no deeper bass extension. However, I'm certain that another option, a 4-sub distributed bass array (dba) system, would prove to be the greatest improvement to your system's overall bass response and, in my opinion, the best solution I'm currently aware of for supplementing and extending the bass response and integrating seamlessly with any pair of speakers, but especially with 'fast' and detailed speakers such as planar-dynamic and electrostatic panels. I'm certain this system would work very well for your system because I've been using a dba system with my fast Magnepan 2.7QR speakers for about 4 years now. I realize the 20.7s are far superior fast speakers than my older models, but the forces behind dba systems' excellent bass performance and integration work equally well with virtually any pair of main speakers. This system has worked so well for my system that I started a thread about it a few years ago, here's the link if you'd like to know more details:
https://forum.audiogon.com/discussions/anybody-else-using-a-distributed-array-sub-system
Also, here's a link to an Absolute Sound review of the Audio Kinesis Swarm dba system, which is almost identical ( the Swarm subs are just a bit wider and shorter) to the AK Debra dba system that I own:
http://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/
There are 2 options if you're interested in setting up a dba in your system: Complete AK Swarm or Debra complete dba system- these include four 4 ohm subs with removable port plugs for either sealed or ported operation, each sub has a 10"aluminum long-throw driver, 14.5"W x 23.75"H x 10.375"D and 43 lbs., and a Dayton Audio SA1000 1K watt class AB mono sub amp that powers all 4 subs, about $2500 for the complete system. Custom dba systems- these would involve buying 4 powered subs of your choice and positioning them asymmetrically within the room for optimum performance. This is the most flexible method of creating a dba system since you can choose the quality of the subs used for bass extension and maximum spls. Either AK dba complete dba system will provide flat frequency response from 20-100 Hz with a maximum output of 113 db at 20 Hz. The bass extension and frequency response performance levels of a custom dba system will vary depending on the exact subs selected. The excellent bass integration quality with your 20.7s, however, will not vary depending on the exact subs selected and will remain constant. Which means a very good dba system could be created for as little as $2,000 if 4 SVS SB1000 subs were used but an 'ultimate' dba system could be very expensive if very hi-end subs are used. Considering this, either AK dba may be the best bargain given their high level of performance in bass extension, accuracy and maximum spl level. Sorry I wrote you a book but I wanted to give you as much info as I could. Tim |
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.
Thanks,
Tim
|
bdp24, 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, Tim |
rauliruegas: "Not for you but for other gentlemans this link could help to understand better the overall bass management:
http://www.soundoctor.com/whitepapers/subs.htm " Hello rauliruegas, 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. Tim |
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
|
Hello rauliruegas,
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.
Enjoy,
Tim
|
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.
Thanks,
Tim
|
Hello hifidream/Steve,
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.
Enjoy,
Tim
|
mijostyn,
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.
Tim
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b_limo: "I think mids and highs are overrated too."
Excellent thread summary, Attorney General Barr.
DJT
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Hello phusis,
Your post brought up many good points and I believe most come down to your personal preferences being different from mine.
I think we both agree that the 4-sub distributed bass array (DBA) concept is something that works incredibly well in virtually any room and with any set of main speakers, even fast speakers such as planar-magnetic and electrostatic panels. I think this is bourn out by the fact that we both use them in our own systems.
All DBA systems will provide accurate, detailed, smooth and natural bass that has an effortless quality to it. But I consider the DBA concept to be an especially elegant bass system solution because of its scalability and flexibility that allows for customization based on personal preferences.
DBA's are scalable mainly by the choice of the 4 subs utilized. I use the relatively small subs standard with the AK Debra DBA system that have a 1 sq ft footprint, are about 2 feet tall and contain 10" drivers. Although this provides bass response in my room that's flat down to 20 Hz it's not quite able to reproduce the entire lowest octave of 16-32 Hz but this bass response has plenty of power, impact, extension and dynamics on music and ht for my preferences. Others who may have a preference for more bass power, impact, dynamics and sufficient bass extension to reproduce the entire lowest octave have the option to choose subs that are as powerful, extended, expensive and large as they prefer or can talk their spouses into.
DBA system's are flexible mainly by the choice of system settings such as the crossover frequency, whether the main speakers are run full-range or restricted and the overall bass system volume relative to the main speakers. I prefer setting the crossover as low as possible, typically in the 40-50 Hz range, because I run my main speakers full-range, they only have accurate bass extension down to 36 Hz, I find the bass sounds better integrated when the subs only engage when the content requires it and I perceive the bass as boosted overall when the crossover is set much higher.
You've stated you prefer setting your crossover at 80 Hz and using a high quality digital xover to restrict the bass output of your main speakers. This not only demonstrates the flexibility of DBA systems but allows other significant benefits as well that you detailed. I understand your point about perceiving the bass in your system as still natural and well integrated even at your much higher 80 Hz crossover. Perhaps it could be we just differ a bit in how we perceive moderately deep bass as it approaches frequencies that we're able to discern where the bass is coming from. But the DBA flexibility still applies since we're both just using the available DBA settings to attain the system performance and other benefits that we enjoy and prefer in our systems.
The overall DBA system volume relative to the volume of the main speakers volume is another important setting that allows significant flexibility. I prefer a bass system volume that is slightly less than half volume on the sub amp which allows the deep bass to be independently powerful, detailed and dynamic while still integrating well with the mid-range and treble of the main speakers as the overall volume level is varied from soft to loud.
But like you, I'm not adverse to increasing the relative bass system volume on certain Blu-ray movies or even some music. Just our personal preferences easily catered to by the flexibility of our DBA systems,right?
Tim
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rauliruegas: "Dear @noble100 : """ All DBA systems will provide accurate, detailed, smooth and natural bass that has an effortless quality to it. """ as can do it non DBA subs system. As you said maybe a different way " to see things " but DBA is not the only or best option. Clearly is for you and other gentlemans but exist other very good alternatives to it." Hello rauliruegas, Yes, it's definitely possible to attain very good bass response using 1 or 2 subs. As we've discussed previously, this is a bit of a compromise since the 1 or 2 subs need to be precisely positioned in the room to optimize the bass response perceived at a single dedicated listening position. This specific sub positioning process for 1 or 2 subs restricts good bass response to the immediate vicinity of the dedicated listening seat and, by necessity, results in much poorer bass response at many other areas of the room. However, some individuals require good bass response at more than just a single listening position and a 4-sub DBA system is an excellent method to achieve good bass response not only at the dedicated listening seat but also throughout the entire room. rauliruegas: "Normally the owners of planar type speakers are " against " to run the main speakers as a " satellite " one that is the " right " way to go ( for me. ) because that high-pass filter makes a paramount difference." I completely agree with you that one of the major benefits of adding subs, and running the main speakers as satellites, is that it frees the main speakers and their amp from reproducing the bass frequencies which results in less speaker distortion and reduces the demands on the amp. In my system, I've tried both configurations of running my planar panel mains full-range and with my mains as satellites with their low frequencies filtered out by the sub amp supplied with the Audio Kinesis Debra DBA system, This amp has a L/R high pass outputs for sending frequencies above the bass crossover setting to the main speakers amps. I thought my system sounded best with the main speakers running full-range. The mid-range and treble range sounded very similar to me with both configurations but I did notice the bass range sounded more detailed and more dynamic with my mains running full-range. I do have some thoughts about why I didn't discern improvements in the mid-range/treble range using the 'satellite method' as expected and as you have in your system. I'm uncertain of the quality level of the high pass filtering being done in the sub amp. But since I was unable to discern any differences in the midrange/treble response range between full-range and the satellite methods, I can only conclude that the filtering quality level is not an issue. Also, any sonic gains expected from the reduction on bass frequency amplification demands on the main speakers amps may not have been realized since these mono-block amps are not lacking in power ( 1,200 w into the speakers 4 ohm load). Another possibility is the Magnepan 2.7QR main speakers I use as mains. These are 3-way planar panels that have rather large bass sections which provide very high quality bass on their own but that lack deep bass impact. Perhaps the improved bass response I noticed with running the mains full range is a result of the very high quality and articulate bass of my mains combined with the increased impact and dynamics provided by the AK Debra DBA system. I think both our systems are just practical proof that there's several options available for achieving high quality bass response using subs. Tim |
Hello atmosphere,
Agreed.
Standing waves result in room bass modes which are perceived as bass exaggeration, attenuation or even cancellation at the specific points they occur at in the room. These room bass modes resulting from standing waves also vary by frequency and typically exist in the bass frequencies up to about 350 Hz.
As I understand how the distributed bass array concept functions, the 4 subs distributed throughout the room actually are intended to create more bass standing waves and bass modes that are fairly well distributed throughout the entire room.
Once there's a good distribution of bass room modes existing in a given room, the principles of psycho-acoustics are then utilized by the DBA concept. Humans are very poor at discerning the originating source of deep bass frequencies (below about 80-100 Hz) but very sensitive in discerning the pitch and the volume of these deep bass frequencies as well as any changes in pitch and volume. Our brains process these multiple bass room modes (bass peaks and dips at various frequencies) by summing and averaging them which results in a perceived smoothing effect to the bass.
Scientific research by Earl Geddes, Floyd O'Toole and others has proven that the more subs in a given room the more the effects of bass standing waves are reduced and the more the bass response is perceived as good(accurate, smooth and detailed). They realized there's a practical limit to the acceptable number of subs in a domestic room, however, and their data showed that some of the bass smoothing effect began with as few as 2 subs in a given room but there was a threshold reached with 4 subs in a given room which mitigated the effects of the vast majority of standing waves in the entire room, with each additional sub beyond 4 only providing smaller and marginal improvements.
This means that 4 subs will assure very good bass response at all bass frequencies throughout the entire room, including the chosen dedicated listening position. 2 subs cannot provide very good bass response throughout the entire room, only at a single dedicated listening position and this very good bass response cannot be assured at all frequencies and with all recordings.
Tim
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wolf_garcia:
"The bass in "other parts" of the room aren't important particularly unless you curl up in the corner for a panic attack or some sort of modern dance move."
Hello wolf,
I agree that good bass response throughout the entire room is not important for many but it is for some such as myself. No, I don't curl up in the corner from my panic attacks or windup there from my very creative
modern dance moves..... at least as far as you know.
It's important for me because I have 6 seating positions spread around my 23x16 ft living room that I use for both music and ht. Only one seat is in the sweet spot, precisely between my main speakers and directly facing a 65" plasma hdtv wall mounted between them. I have my dipole panel speakers positioned about 4' away from the front wall for optimum freq. response and imaging at the sweet spot seat. This works great for music at this seat but, of course, the stereo imaging effect is compromised at the other 5 seating positions along the left and right walls although the bass response is excellent at all seats.
But music still sounds very good from these 5 other positions and, since all 5 have a clear view of the hdtv, it works very well for ht, too. The 5.4 surround experience (5 speakers and 4 dba subs) is very good from all 6 seats in the room. The bass response is outstanding, equally deep, detailed, powerful and dynamic from all seats with still very good mid-range/treble surround sound response and perception at the 5 non-sweet spot seats.
With the volume goosed a bit on Blu-ray movies, the impressive bass impact can normally be relied upon to have at least 1 family member or guest jumping out of their seat at least once during any action movie at a bass intensive scene.
Tim
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rauliruegas: "Dear @noble100 : HT and stero MUSIC reproduction room/systems needs are different. Maybe that’s why you are the only audiophile I know that can’t be aware of the difference using a high-pass filter in the stereo music main speakers and with out that filter even the wider frequency range in those bass drivers. Not only that but you said you preffers with out the high-pass filter because better bass quality performance." Hello rauliruegas, Why do you believe the reproduction requirements/needs of HT and stereo music are different? I believe a single system that is able to reproduce the full 20-20,000 Hz frequency range accurately, with low distortion and proper dynamics is fully capable of reproducing both with high quality. My combination stereo music and ht system is fully capable of reproducing the full range of audible frequencies with high accuracy, very low distortion and powerful dynamics and, therefore, performs with high overall quality for both stereo music and ht. You also seem to have difficulty understanding why I didn’t notice a significant improvement in the performance of my Magnepan 2.7QRs main speakers when connected to the high pass filtered outputs on my sub amp rather than being run full range. I believe you need to understand the details of my system to understand why I prefer running my main speakers full range. I built my system from the bass up because good bass response forms the solid foundation for most music and ht. Bass is also the most difficult portion of the frequency range to achieve high quality performance at in most home rooms due mainly to the extreme length of bass sound waves which are longer as the frequency decreases. For clarification, a 20 Hz deep bass full cycle soundwave is 56 feet long and a 20,000 Hz high treble full cycle soundwave is a fraction of an inch long. The system solution I decided upon was to construct a separate high quality bass section for reproducing frequencies from 20-100 Hz, which is the frequency range of my 4 subs, and a separate high quality full range section for reproducing frequencies from 35-20,000 Hz, which is the frequency range of my main 2.7QR speakers, and blend the 2 sections together seamlessly by precise adjusting of the crossover frequency and relative volume settings of the bass section. I consider this system solution to have been a total success with the crossover set between 40 and 50 Hz and the sub amp relative volume set just under halfway at about 11 o’clock on the dial. I’m not exactly sure why you notice such a big improvement in your system performance using hi-pass filtering while I don’t. I use a crossover frequency of 40-50 Hz compared to your 80 Hz. Any sonic gains expected from the reduction on bass frequency amplification demands to above 40-50 Hz on my main speakers amps may not have been realized since my mono-block amps are not lacking in power with 1,200 watts into the speakers 4 ohm load, so there’s no lack of power from the bass to the treble. The sonic gains of your amps being relieved of bass amplification demands to above 80 Hz, however, seems to have been much better realized. Do you think more regular and reserve power being freed up for your speakers midrange and treble drivers could be the reason you notice improved performance in those frequencies? Another possible explanation of why I don’t prefer using the hi-pass filters in my sub amp could be the Magnepan 2.7QR main speakers I use as mains. These are 3-way planar panels that have rather large 620 square inch bass sections which provide very high quality bass on their own but that lack deep bass impact and dynamics. Perhaps the improved bass response I noticed with running the mains full range is a result of the very high quality and articulate bass of my mains combined with the increased impact and dynamics provided by the AK Debra DBA system. I’m unsure of how well the bass quality of your ADS speakers run full range would combine with the increased impact and dynamics provided by your Velodyne subs. Perhaps you can try it sometime and find out. Tim |
steakster,
Subs in corners, since they couple to two walls, typically results in a 3 db+ bass boost. It sounds like you're making the right moves, keeping your subs way from the corners and controlling the effects of a suspended floor, to keep the bass clean and accurate, detailed, smooth and natural.
Enjoy,
Tim
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Hello brskie,
I’d suggest going with the Treo and 1-4 moderately sized subs would definitely be the more versatile option when compared to a pair of Quatros with no subs. I’ve never compared the Treos to the Quatros by themselves but I’m still fairly certain that either’s overall performance would be improved with even just a pair of well positioned subs. I maintain this opinion even though I’m aware the Quatros have built in powered subs and claimed bass extension down to 24 Hz +/- 2 dB.
The main issue, from my perspective, is that these are both floor standing tower speakers and that virtually every owner is going to position them in their rooms so that the optimum midrange/treble response and stereo imaging is attained at the designated listening seat.
The bass drivers are just along for the ride, located in the room a matter of inches or feet directly below the midrange and treble drivers. The apparent assumption that this positioning will also provide optimal bass performance at the listening seat is highly unlikely bordering on fat chance and no way. I believe it’s a distinct and very significant advantage to have independently positioned bass producing drivers in virtually any room and any system.
I even suspect that a pair of Treos, combined with a $2,800 Audio Kinesis Swarm 4-sub distributed bass array(dba) system, would outperform a pair of Quatros without additional sub assistance. It’s also very possible a pair of Treos, combined with just a pair of good quality and well positioned subs (a used pair of Vandersteen 2wq subs for example), could outperform a pair of Quatros without additional sub assistance when judged from the designated listening seat.
I should mention I highly respect the Quatros along with Vandersteen speakers in general and my intention is not to disparage them. It’s just that I know, through research and personal experience, the near sota bass response attainable with at least two and up to four good quality, well positioned and properly configured subs in virtually any room and system. I think a pair of Treos combined with a Swarm type bass system, at a combined price new of about $9,800, would be an excellent performer and a unique audio bargain.
Best wishes,
Tim
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