Why is good, deep bass so difficult? - Myths and their Busters
My video system goes down to 16 Hz - but really you don't hear as much as feel at that frequency! My main audio system is 3 dB down at 20 Hz - adequate for just about any music. You can be happy with speakers that have not much below 30 Hz, but once you know what is there, it is hard not to miss it. |
Hi @cousinbillyl Slightly different topic. That is about perceived impact and multi-way speaker design with passive filters. Impact is not actually deep bass. That’s just regular bass. :) A powered subwoofer would skip the inductor/filter issue altogether. Not the first time I have read this statement, so there may be some truth to that, but there are a couple of myths too. Good cored inductors with very low DC start rather inexpensively. The issue with designing a low pass filter is more complicated than merely reducing the DCR. No one should start replacing coils willy-nilly. There are a number of issues that can be introduced by doing so. Best, E |
gkr: The amps and speaker matching are certainly a factor. I remember the first time I really heard a difference in amps was watching the dealer swap in a Tandberg to play Snell A/IIIs. Remarkable power, smoothness and extension. I was quite enamored. The "trick" to the Snell's bass was woofers with significant amounts of added mass however, so it is unlikely these drivers have survived up until now. I recently owned a Tandberg amp again, though, and have to concur with the original reviews which called them grainy on the mid/treble. << sigh >> harry: Very few speaker designers really appreciate the value of designing speakers for a room / location instead of quasi-anechoic. That's how I design mine and it's a huge help. Best, E |
For great bass you must isolate your speakers from there environment, remove the spikes and replace with Townshend Audio Seismic Podiums or Seismic Speaker Bars, your speakers will then be free from any boom or distortion which will allow you to hear/fill your speakers best bass performance plus the rest of the frequency’s become much clearer open and natural please check Max Townshend you tube video Spikes v Podiums I use Podiums with my Sound labs Dynatats my bass is awesome, the hole sound has improved good luck but great bass is very possible once you have isolated your speakers from there environment. |
Skanda wrote: "Do sealed speakers integrate better into these rooms?" It’s ALWAYS a matter of speaker + room, and if the room is contributing a lot of boundary reinforcement, sealed boxes generally result in better synergy. If not, then vented boxes generally result in better synergy. I can go into more detail if you’d like, BUT the specifics ALWAYS matter more than these sort of generalities. * * * * A lot of different suggestions have come up in this thread, things that have obviously worked for the people who tried them. Because of the ear’s exaggerated sensitivity to small changes in SPL at low frequencies (shown by the bunching up of equal-loudness curves south of 100 Hz), combined with its poor time-domain resolution (which is why we can’t localize the source of very low frequency sine waves), we can infer that the improvements we hear are primarily due to changes in SPL, even if they "sound like" changes in "speed". At the risk of over-simplifying, and being open to correction on any of these points, some things simply make a bigger difference than others. To set the stage, it’s not uncommon for in-room response across the bass region to have peak-to-dip swings of ballpark 12 dB, or +/- 6 dB. Changes to speaker damping (mechanical or electrical or acoustics) seldom result in more than a 1 dB difference, but in the low bass region that's as audible as a 2 dB change in the mids. Improvements to room acoustic damping (bass trapping) can result in 2 dB or maybe 3 dB reduction of the maximum peak-to-dip swings. EQ is generally good at chopping off the peaks but not so good at filling deep dips, still +/- 3 dB is often feasible, and perhaps better if optimized for a small sweet spot. A distributed multisub system results in smaller and more numerous peaks and dips (which has psychoacoustic benefit), with +/- 3 dB over a wide listening area being reported by many users. Remember, smooth bass = "fast" bass, perceptually. The good news is, these different approaches are not mutually exclusive. You can start with one and then add another as your piggy bank recovers. One final implication of the bunching up of the equal-loudness curves south of 100 Hz is, there is subjectively a LOT of room for improvement over the typically poor low frequency response of most speaker/room combinations. Imo, ime, ymmv, etc. Duke |
gkr7007 wrote: "...I gravitate toward planars and other very fast response speakers." Planars are subjectively "fast" because they have smoother in-room response than monopoles (even though the actual low-frequency transient response of their diaphragms is often quite poor, certainly not "fast" at all). This smoother in-room response of dipoles arises from the 180 degree phase difference between the backwave and frontwave, which effectively launch in opposite directions. When the frontwave and backwave meet up again, after several bounces off of room surfaces, their phase response is significantly more randomized than would be the case for a monopole speaker’s room bounces. And the sum of highly random-phase bass energy is much smoother than the sum of largely in-phase bass energy. "Decorrelation" is the proper word... decorrelation = smoothness, and is highly desirable in the bass region, and is something big rooms do better than small rooms. Decorrelation is also the advantage that a distributed multisub system offers over a single big sub... same basic mechanism as planars, but set in motion by different means. As the wavelengths get very long relative to the room dimensions, planars tend towards cancellation because half of their in-room energy is out of phase with the other half, so planars don’t make very good subwoofers unless they are very big and can move a lot of air, and are in a big room. In general, two intelligently-positioned monopole subs approximate the in-room bass smoothness of a single dipole main speaker. So it takes four intelligently-positioned monopole subs to approximate the in-room smoothness of two dipole mains speakers. Duke |
Most speakers will provide plenty of bass. My personal experience with a pair of Elac FS209.2's for stereo use, running them with a cheap DAC and a fairly cheap amp (adcom GFA 5802) was that they were completely under performing when it came to bass. I was using good cables (cardas neutral reference) I tried a sub woofer and it just didn't match the speakers in there quickness... mind you I tried with a home theater sub and not a musical sub.... Then I read some where that they were a demanding speaker and required a good amp to command them properly. Fast forward to today with some front end equipment upgrades I'm getting very impressive bass from these speakers and have no need or desire for any kind of sub... I have effectively solved my bass issues. The low end notes are so tight and precise it still amazes me... who ever hears my system asks me where the sub is... lol My main upgrades were a new DAC (Yggdrasil) and new bryston 7B3 mono blocks.. Also a used LS26... but the preamp was the final edition and bass was achieved prior to its integration in to the stereo. I can strongly suggest that the majority of lack of bass issues is the result of inadequate quality amplification.. As another poster here already mentioned... Now that I have bass ... fine tuning it is another story altogether ... now we get into speaker placement and room treatments.... Just my 2 cents from personal experience.. |
There are a lot of good points here. . . I thought my 20.1 Maggies went low until I got the subs set up and dialed in. The difference is incredible. Friends come over and expect to be blown from their seats but with proper speaker placement, using multiple subs, and room correction all they get is an tuneful accurate sound. The support that the subs give to music is very satisfying. After I get asked to turn it up two or three times and get close to symphonic concert levels comments are that the system is so "clear." They don't understand how it can be so loud but not hurt their ears. While I don't think people need to be acoustical engineers or physicists to get the best from their systems understanding basics can make a huge impact. Room interactions are almost as important as the system itself in my opinion. |
So here are a few things to consider. 1. Most woofers double. 40 Hz turns quickly to 80 Hz. 2. The law of physics would dictate that a 10" woofer will not keep up with a 6" midrange. Too much mass. They must use very stiff suspensions to bring them back to neutral position after each excursion. 3. Woofers are screwed into a large piece of MDF. The very back and forth movement of the diaphragm causes that piece of MDF to resonate. 4. Massive objects resonate at frequencies that are hard, very hard to deal with. |
My system for the three years was using stereo subs and a DSPeaker Antimode 2.0 to do the room correction . I was happy with my bass response until I heard a distributed bass setup at a listening session at another audio files home .Back to the drawing board . I added in two more subs . Installed hi pass caps in my amps used my DSPeakers crossover and stereo sub correction function and good old listening to adjust the levels and now have the best most even bass response in my listening room to date . Duke is right in this case more subs is less boom in the room . |
That a 12/15" woofer is "slow" is a myth, I’m sorry, I’ve proven it over and over again and much smarter physicists than I have explained it. The real issue is that they produce too much deep bass, which integrates poorly in a room without attention. Give me bass traps, EQ and a pair of 15-18" woofers and I’ll scare you right out of the room they are so fast. As I recall, the large woofers have to move fractions of the small woofer, and have much larger motors, so any issues of mass are more than offset by efficiency (in regards to displacement vs. Hz). Rule of thumb I learned a long time ago, and I may misremember, is that doubling the drivers is the equivalent of using a single driver 2" larger. So for instance, 2x 8" = 1 x 10" driver. 2 x 10" = 1 x 12" and so forth. Point is, there is just no substitute for raw surface area if you want deep and low distortion bass. As I noted at the first posting that started this thread, I can really see why this myth is so attractive. Now, about movement, yeah, you have something, not only the baffle, but the entire speaker can move due to the woofer forces. Cheap fix: Add weights to the top of a speaker. Like 20 lbs at a time. :) Best, E |
To state "a 10" woofer will not keep up with a 6" midrange. Too much mass." is to oversimplify the situation. For one thing, different 10" woofers and 6" midrange drivers have differing amounts of mass; there are some 10" woofers with less moving mass than some 6" midrange drivers. But more importantly, the moving mass of any given driver is only one factor determining it’s "speed"---the size of the driver’s motor (magnet) is a huge factor. A driver with higher moving mass and a bigger motor can outperform a driver with lower moving mass but a smaller motor. By the way, the perceived "speed" of a driver is more a matter of how fast it stops moving when the signal does, and returns to "rest", than it is of how fast it starts moving. The cone of a dynamic driver not stopping when it should is called overshoot. As Newton’s Laws of Motion state, "A body in motion tends to stay in motion"---my own over-simplification! Likewise, the statement "They must use very stiff suspensions to bring them back to neutral position after every excursion" is not universally true. The stiffness of a suspension is only one factor in the design of any driver, one needing to be balanced against other factors. Some very high performance woofers have stiff suspensions, some don’t. Acoustic Suspension designs (sealed enclosures) require suspensions with far less stiff suspensions than do Bass Reflex, for instance. Woofers ARE often placed in MDF enclosures, but they don’t have to be, and sometimes aren’t. Baltic Birch plywood is a popular material used by some makers of high-performance subs. That plywood is far stiffer than MDF, it’s resulting resonance at a higher frequency than that of MDF, optimally far above the x/o frequency of the subwoofer. "Massive objects resonate at frequencies that are hard, very hard to deal with". Sorry, also not necessarily the case. Internal bracing very easily and effectively deals with subwoofer enclosure-wall resonances, the braces pushing those resonances above any frequency the sub will be called upon to reproduce, reducing their audibility to below perceptible levels. |
Soundrealaudio wrote: "[Woofers] must use very stiff suspensions to bring them back to neutral position after each excursion." The suspension system is not what brings the woofer's cone back to the neutral position. IT IS THE AMP!! As long as the amp is sending signal to the woofer, ITS MOTION IS ALWAYS BEING POWERED BY THE AMP!! It never has to rely on the suspension system alone. In more technical terms, Qts is almost always dominated by Qes; Qms typically makes only a minor contribution to Qts. Duke |
+1 Audiokinesis and Erik 15" and larger woofers are key to good bass. You can’t beat the advantage of a large surface area except with multiple woofers. Multiple woofers are harder to drive so not a good choice. Basically.... One 15" woofer is equivalent to Two 12" woofers Three 9" woofers Six 6" woofers The amp controls the woofer and the air suspension suppresses the resonance of the woofer if properly designed. A woofer designed to work without a box may have a stiffer suspension but these are an exception rather than the norm. |
erik Placing weights on the top of a speaker may change the sound, for the better, I don't know, my speakers have sloped tops so I can test that out. I can tell you that you will not control cabinet resonance by adding weight. You might change the resonance point. Remember that light objects have higher resonance, more massive objects have much lower and much more difficult to control resonance. Simply take a wine glass and ping it with you finger nail. Now to stop the glass from ringing simply touch it with your finger. Two laws of physics come into play here. The first is that low mass objects will resonant at a high frequency. the second is that composite objects will more quickly do away with unwanted resonance. When you touch the wine glass with your finger you are essentially creating a composite of materials, your finger and the glass. Two disparate materials. So I conclude with this: Purchase speakers that are made from composite materials. Two do not always assume that those big heavy massive speakers will have better bass. |
The weights issue of course is very much speaker dependent. :) I’m certainly not saying it is THE solution to THE speaker problem. :) This particular issue isn’t resonance within the speaker panels so much as force and leverage vs. the mass of the entire speaker being able to rock the entire assembly. Of course, those of you with 200 lb speakers can ignore this issue. The woofer motor exerts quite a bit of force that changes rapidly. This could in theory actually move the speaker, or tilt it, causing some self-cancellation akin to the Doppler effect. Should you spend a lot of time and money on this particular issue? I don’t think so. I used to own Focal Profile 918. Rather tall, light weight speakers with woofers mounted relatively high. That is the type of speaker I think would benefit most. Having force up high gives it more leverage, and more ability to rock the speaker back on it's rear feet. The Profile was easy to knock over even with after-market supports. The theory is basic physics, but I haven't done any modelling in regards to "normal" woofer forces and speaker masses. If you are worried, put a nice steel weight on top and listen. Then if you hear no difference at all send me a case of Casamigos tequila on top of which you have written the words "You were totally wrong." Best, E |
It’s not really a mass issue for the tops of speakers. It’s placing something that acts like a diode and allows the otherwise trapped energy in the speaker cabinet to rapidly escape to the outside air via a path of least resistance. This is why things like those Totem Beaks or cones, especially NASA grade ceramic DH Cones, very hard but not very massive, but massive enough, are often so effective placed on top of speakers. 🍦 There used to be a product Tekna Sonic that was purpose built for attaching to speaker cabinets that accomplished the same thing. For the same reason cones can often be placed on top of the electronics chassis or tube traps and accomplish the same sort of thing, dissipate energy rapidly from the system. Crystals also dissipate mechanical energy in similar circumstances. |
I don’t know but I have a sneaking suspicion nobody ever ran curves for anything from the listening position. That’s not something in an audiophile’s bag of tricks. 👜 What audiophiles do is try something. Listen. Move it a little. Listen again. Try something else. Listen again. Ad infinitum. And they wonder why audiophiles frequently come down with a bad case of audio nervousa. 😬 |
I’m not sure how many different ways I can type this. If you are thinking of resonance cabinet control it is VERY different than what I am describing. Imagine an open baffle speaker design of zero mass resting on frictionless rollers. As music plays, the speaker will roll back and forth on the skates, and the acoustic output will be reduced. This is the equal and opposite reaction to the energy of the motor acting on the baffle/motor and motor frame. This is a matter of force, leverage, and mass. Is it an issue? I don’t know, I have had a number of people whose opinions I trust say they get better bass out of monitors with additional mass, which need not be particularly modern. An antique iron would work if it was heavy enough. Best, E |
Yamamura used to make some very elegant limited slip plate thingamabobs for speakers. You can actually knock them off if you know what you’re doing. Limited slip plate devices offload excess energy from the speaker cabinet by converting that energy to work performed by the movement of the speaker allowed by the 3 piece limited slip plate arrangement under the speakers As far as mass goes, what can I say? People say things. People talk. Some people swear up and down that VPI bricks work due to increased mass. What else is new? |
When I say speed in this context I mean ability to produce deep bass through bass (16 Hz - 100Hz). Your average consumer 15" woofer of course will be crappy by 200 Hz or higher. The reason the "lighter drivers must be faster" is not accurate in this case is because the final, total performance of a woofer is not just mass and inertia but also magnet strength, efficiency and required displacement for a given output. The amount that a 15" woofer has to move for a 25Hz signal is minuscule and far more efficient and lower distortion than an 8". The entire system matters (including the room). To say a small woofer must be "faster" in bass is like saying a go-cart must be faster than a Honda Civic because it’s lighter. The only way that model is complete is if you are pushing both. Mind you, I love the 6.5" woofers in my main speakers!! :) But they will never have the deep bass and the speed and glorious output of my 15" sub below 40 Hz. As hard as it is to properly integrate large speakers into a room, few audiophiles get to hear how magnificent, fast and low distortion a big sub can be. I'm also really done repeating this. Buy whatever you like, and listen to what you like. Best, E |
Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms by Floyd Toole |
Large 15" woofers don’t have to do higher frequencies and are never required to operate as fast as a tweeter! Duh. Face Palm. However they do reproduce bass frequencies orders of magnitude better than small 6 or 8" woofers. Those who would deny this are just drinking maketing BS. Clearly some people are unaware of the physics of a large surface area vs a small one and the Xmax (linear) limitations of voice coil travel. Slow bass or poor PRAT is a combination of poor timing alignment, poor frequency response balance between mids tweeter and woofer, as well as resonant Q tuning and port tuning of the box. A dip in the mid range will reduce bass punch. High Q systems resonate and make the bass "hum" or sound "blurred" rather than "punch". Exceeding Xmax or a long voice coil in a short magnetic gap means non linear response, excessive compression from heat and a dull boomy smeared bass. Dull boomy smeared bass is what most 6 or 8 inch woofers with cheap 1 inch voice coils do! A 15" woofer with a 3 or 4" voice coil is a much better design, as far as audio fidelity is concerned at LOW frequencies. Of course you can’t expect a 15 inch woofer to even begin to do the mid range like a 6 inch can. 6 inch is a monitor or toy size when it comes to bass and 15" is professional. You simply can NOT find a reputable studio with large main monitors that have 6 inch woofers and there is a good reason you can’t! So please stop repeating the marketing BS about fast small toy sized woofers! |
"...go-cart must be faster than a Honda Civic because it’s lighter..." It would be if it had the same engine.... Weight is only one of many parameters that affects "performance". It strikes me that folks are talking past each other through this (pointless) thread. Like everything else, there are multiple variables that determine the relative performance of woofers. I think that's probably the only statement that makes sense. |
Recently switched from large'ish ported speakers with 4, 7-inch bass drivers each and a single high-quality sub to "monitor" speakers with 2, 9-inch LF drivers each in a sealed 100+ lbs. box and two high-quality subs from the same mfg and the bass response went from pretty good with occasional overloading of the room to what is now the best I have heard. Driving the mains with high-powered Class A monos and the subs with their own internal amps - the subs definitely keep up. |
@soundsrealaudio Can you find any multi million dollar recording studio using 6" toy size woofers for bass on their main monitors? You can't because these are professional facilities that do things correctly without following some weird urban myth about woofer speed (probably started by an ignorant hobbyist reviewer or a monitor (toy) sized speaker manufacturer). |
This is interesting, from wikipedia: Equalisation of the sound system to compensate for the uneven frequency response caused by room resonances is of very limited use as the equalisation only works for one specific listening position and will actually cause the response to be worse in other listening positions. Also large bass boosts by sound system EQ can severely reduce the headroom in the sound system itself. Some vendors are currently providing elaborate room tuning equipment which requires precision microphones, extensive data collection, and uses computerised electronic filtering to implement the necessary compensation for the rooms modes. There is some controversy about the relative worth of the improvement in ordinary rooms, given the very high cost of these systems. |
Not a recording studio, but Sterling Sound Mastering in NYC have three pair of Rythmik F15 Direct Servo Feedback Subwoofers in their monitor systems, each with a 15" woofer. Killer bass. Rythmik owner/designer Brian Ding has been asked about the question of woofer diameter versus "speed", and his answer is that his 8" and 12" woofers are no "faster" than his 15", but that the 15" has higher maximum SPL output. Of course, the woofers in his Rythmik subs are servo-feedback controlled. I have both 12" and 15" Rythmik Subs, but the woofer size is the least important difference between the two. The 12" are used in pairs mounted in Open Baffle H-frames, the 15" in a 4cu.ft. sealed enclosure. OB subs are very different sounding than both sealed and ported, for a number of reasons I won't go into here, but the point is the size of their woofers is not responsible for the difference in sound between the two. |
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@soundsrealaudio So you obviously could not find any (not one) high end professional studio facility using 6 inch woofers for their main monitors!!! I hope you learned something. 6 inch woofers being fast is a myth. As far as bass is concerned 6 inch woofers are woefully inadequate except in near field setups where a compromise in bass response, accuracy and dynamic range is acceptable for convenience and cost benefits. |
The great myth about subs is - while many audiophiles expect their subs to be fast - there is nothing fast or quick about 20 HZ or even 30 HZ. While there are good and bad subs "there is no such thing as a fast sub". The job and the only job of a good sub should be to faithfully produce the bottom octave/octaves of your musical presentation. A good sub should always be filtered to operate only below 50 or 60 HZ, otherwise you're expecting it/them to do the job your high dollar stereo speakers (regardless if they are panels or boxes) should be doing. While I'll not argue the importance of the quality of driver/drivers, cabinet, electronics and design, needed to make a good sub, the size of drivers and cabinet and the amount of power needed to drive it to a level that meets your expectations, is completely dependent on the amount of space you're asking it to fill. Because frequencies below 60 HZ become non directional and interact differently with the room and to the listener than higher, more directional, frequencies. Even in a live performance the lower notes of a string base, base guitar, or organ sound displaced and more felt than heard. It is more critical to match your sub/subs and power to the room than to your speakers. |
The Rythmik Direct Servo Feedback Subwoofer system is a very sophisticated design (patented, for what that’s worth)---many subs are nothing more than a woofer and an amplifier in a box---that accomplishes a number of goals for it’s designer, PHD Brian Ding. For instance, all loudspeaker driver voice coils heat up with use, slightly altering the driver’s electrical characteristics. The Rythmik DSF compensates for changing woofer coil temperature, keeping the driver’s electrical characteristics consistent. All woofers, in fact all drivers, would benefit from that. All drivers have a rise time (when hit with a signal), and a return to "rest" capability (when the signal stops), ideally not over-shooting the "at rest" position of the voice coil within the magnetic field of the driver’s motor when attempting to do so. Servo-feedback systems, found in the woofer columns of the Infinity IRS and RS-1b (which I use to own), have long been known for affording superior inter-transient silence, another term for non-overshoot driver performance. There are a few ways to achieve high performance in that regard, servo-feedback being a cost-efficient means of doing so. The Rythmik subs excel at that performance characteristic. Just as the Eminent Technology LFT driver has been described as "quiet" (very low "noise"), the Rythmik subs have a very high degree of inter-transient silence. They are unusually good at blending with planar loudspeakers, sounding "leaner" (no bloat) than most other subwoofers. The Rythmik sub designed in collaboration with GR Research’s Danny Richie, the only OB/Dipole sub in the world featuring servo-feedback woofers, is State-Of-The-Art. A pair of those subs (usable up to 300Hz), combined with the Eminent Technology TRW-17 Rotary Subwoofer (designed to be used for reproducing 20Hz and below!), greatly exceeds the capabilities of any other subwoofer in existence. Not cheap (the TRW-17 especially), but cheaper than the woofer section of the $100,000 and above loudspeakers available to the well-heeled. Rythmik owner/designer Brian Ding has a very detained explanation of his designs on the company website, for anyone interested enough to read it all. Warning---it’s quite technical! |
I think there is a lot of pretentious blather around this subject…any good main speakers in a normal room (furniture, books, things people simply own) should sound great if pointed at you properly, which requires some moving of the things away from walls, toward walls, wider apart, closer…until YOU think it's sounding good. Then get a sub or two (I use a pair of "previously owned" "Q Series" RELs), move 'em around until they seem to sound good, and relax. Done. If you think you think you need DSP then add that, although I don't like it. A friend uses the same main speakers I have (Silverline Prelude "D'Appolito" arrayed small woofer things) with 2 RELs like mine, and the DSP simply seems to strangle the sound somehow, so I remain without EQ of any sort, other than sub level tweaking here and there. |
johnk Schrodinger didn't microwave a cat. He came up with a thought experiment Schrödinger's cat about the bizarre nature of quantum superposition's. To me one making such a wrong comment in a technical article shows incompetence of author. I trust he was attempting a little audio in light of the fact microwaves had not yet been invented in 1935. Maybe the author would have been well advised to write, Schrodinger was the dude who shot the cat, or poisoned the cat or smothered the cat. Say, how could the cat live inside the box with no air? |
johnk Schrodinger didn’t microwave a cat. He came up with a thought experiment Schrödinger’s cat about the bizarre nature of quantum superposition’s. To me one making such a wrong comment in a technical article shows incompetence of author. I trust he was attempting a little audio humor in light of the fact microwaves had not yet been invented in 1935. That didn’t come along for another 10 years. Maybe the author would have been well advised to write, Schrodinger was the dude who shot the cat, or poisoned the cat or smothered the cat. Say, how could the cat live inside the box with no air? More to the point the cat was alive. It was alive AND dead at the same time. Duh! 😛 |
