Why is good, deep bass so difficult? - Myths and their Busters
This is a theme that goes round and round and round on Audiogon. While looking for good sources, I found a consultancy (Acoustic Frontiers) offering a book and links:
Every audiophile who is dissatisfied with the bass in their room should read these free resources.
Let me state unequivocally, deep bass is difficult for the average consumer. Most audiophiles are better off with bass limited speakers, or satellite/subwoofer systems. The former limits the danger you can get into. The latter has the most chance of success IF PROPERLY IMPLEMENTED.
The idea that large drivers/subs are slow is a complete and utter myth. Same for bass reflex. The issue is not the speed of the drivers. The issue is usually that the deeper a speaker goes the more it excites room modes, which the audiophile is then loathe to address.
Anyway, please read away. I look forward to reading comments.
klh yes room acoustics but more specifically, speaker interactions with floors. Especially suspended plywood floors but most any with any give. Floors often ring like a bell at bass frequencies and speakers transmit a lot of energy to them directly via physical contact if not isolated. If flooring is not solid concrete foundation, isolate your speakers from them first and go from there if still needed.
Whart yes all recordings are different but room acoustics in general will greatly affect most still even when the "proper" bass is not there. I say proper with reservations because its up to the recording producers to determine what goes into each recording. So you want to reproduce what is or is not there accurately. Trying to make recordings sound like something they are not is public enemy #1 in regards to staying on the hifi merry go round forever.
@mapman I don’t know if it is #1 on your list, but in my experience playing LPs, some records simply don’t have much deep bass. Whether it is a result of the original recording, the mix, or the mastering, it isn’t there. There are many times listening to a record where I wish it had been mixed differently. One example: I have both first and second UK pressings of In the Court (KC) and though highly regarded in prog circles as an UR album, it is not a very good recording. Though I’ve long clung to my records and analog recordings (to the extent you are buying old records), the SW remix of the record is a vast improvement in my estimation. Yes it is digital but you can hear Greg Lake’s voice much more clearly, there is far less distortion on certain tracks and everything seems much easier to take in. Much as I love the old Island pink labels, Wilson’s work was, to me, a vast improvement on an important record.
I’ve found out by far what public enemy #1 is in most cases when it comes to hi fi bass performance in most home systems and have cited it in various past posts.
I have been working with sub-woofers throughout my life. Spent years in concert reinforcement and recording industries; upon retirement moved on to high-end audio and home theater systems, designed and built car audio competition vehicles.
Car audio provided the finest educational process in learning how to manage and marriage subs to main speaker systems. My dear friend, the late Jay Thomas designed and built over one hundred custom subs to fit in a host of vehicles even those where most said it could never be accomplished. Car Audio is one part of the industry where design and function demands for sub integration are more complex than any other division. I was fortunate to experience building and listening to every type of sub design imaginable and soon realized that no matter what the construction, operational methodologies or supporting equipment selections there were always issues establishing a seamless sonic blending to the primary speaker system.
We were quite successful in building IASCA winning vehicles. Our secret to gaining the upper hand over subharmonic issues were to mechanically ground the subs, amps and anything else we could direct couple to the car chassis using the only two high end products available at that time which were TipToes and Audio Points. Even when adding multiple DC batteries to increase electronics’ dynamic headroom; when mechanically grounded, they too played a huge role in improving sound quality.
Subwoofer integration is a “mechanical issue” and should be approached as such. Subwoofers create a host of problems associated with resonance caused from vibration. There is resonance build up on the driver assemblies and frames, speaker enclosures and more importantly prohibits the internal electronics package to perform efficiently.
We could never figure out why High-End Audio chose to put amplifiers and crossovers into vibrating boxes containing large woofers. In the early days, most speaker manufacturers simply offered their home theater products to high end listeners and it appears their build and use philosophy stuck. Outside of user convenience, we are still at a loss for why manufacturers go all out in other parts of the industry yet tend to lessen their efforts surrounding subsonic.
The all in one box literally opens Pandora’s Box establishing a whole new set of problems knowing how resonance formed from vibration negatively affects sonic performance. Granted, it costs more money to outboard an amp and crossover (individual component selections are another huge benefit) add more cable, more AC distribution, more vibration management and racking however there is much to be said about subwoofer integration by implementing separate outboard components and individual speaker only enclosures - much more. After all, this is High End Audio - right?
We listened to various electronic solutions attempting to solve mechanical issues that boast seamless sonic integration, however did not hear any products that matched up sonic performance to the marketing hype. In my opinion, current day electronic solutions in attempts to solving mechanical issues remain a work in progress.
Likewise, if resonance issues can be properly managed, significantly reducing audible and inaudible floor noise you avoid having to implement acoustic traps, etc keeping the environment less cluttered with more open space for attack, sustain and decay characteristics to fully develop without the need of additional energy absorption processes that take away from the ever fragile “live dynamic”.
If you do not treat mechanical influences established by the woofer systems, one may never discover what a realistic seamless transition provides musically. You may never know the benefits of subwoofer integration and may come away with that age old saying “subwoofers do not belong in high end audio”.
Our advice is to speak with experts involved with vibration management about your main speakers or sub system relationships as there are products available for gaining the upper hand and attaining that seamless “musical” transition.
Subwoofers dominate the overall sound of the system and more importantly the overall sound and functionality of your room environment.
There is a lot of evidence in audio where one can acquire deeper bass response in full range speakers as well. Lack of deeper bass response or sluggish bass as described by many can be attributed to loudspeaker and/or electronic component operational efficiency - another mechanical characteristic.
We are more than happy to discuss component and loudspeaker operational efficiency which is extremely crucial to performance or provide an audition in your own home so you can hear the differences engineered mechanical grounding products provide sound.
I have been a sub woofer fan for a long time, until recently (my last speaker upgrade), I've used stand mounts. I do find that integrating a sub with the side speakers and especially with the room can be a time-consuming and frustrating challenge. My last sub purchase was the most difficult to integrate, as the room had this "single note" sound it added to the bass. To solve that I purchased a calibration microphone and REW (Room EQ Wizard software), and one by one purchased and installed bass trap panels from ATS Acoustics, which are reasonably priced and very well made. I currently have 10 traps installed in my 24x26' listening room, and could probably add another one or two, but don't want to deaden the higher frequencies.
When we added the Naim Statement S1 pre-amp to our main demo room system we were surprised at the leap in bass performance, power control and depth. That’s without changing amps, speakers, sources or speaker position - far greater than swapping speakers or power amps. We needed to add a very large bass trap to accommodate this change, otherwise we would have needed to reposition the speakers to compromise the bass. Usually we find the biggest disappointment with audio systems is close to the source or the source itself and I think good bass is no exception. Jeremy Bicknell Basil Inc. Audio Systems
In addition with the Torus, the 18" carbon fiber diaphragm operates like an electrostatic. In push pull. It is bi-wired so there is no stiff suspension to slow it down. I is its own servo.
This is the promise of technology and good engineering, not just100 lb magnets and 8" of travel.
So with my two Torus Infrasonic Generators I don't use any room treatments. My theory on why that is goes like this: The bass they produce is not doubling at 40 hz causing 80hz room resonating frequencies. There is extremely low cabinet resonance which again gets the room excited.
Room acoustic treatment is the real key for getting deep and clean bass. My system was drastically upgraded through the use of less than $500 of materials. A good reference is http://arqen.com/acoustics-101/room-setup-acoustic-treatment/ Again, it is very cost effective to build your own panels.
After reading Vade Forrester's equipment review of the Syzygy 870 Subwoofer with Equalization in this September's issue of TAS I ordered one from Amazon.
It has worked out great. EQ cannot be overstated. It makes all the difference. I've tried other subs over the years, but could never get one that didn't sound like a jukebox.
The Syzygy approach is brilliant; and affordable. At only $999 you can't go wrong; and if you buy it from Amazon and don't like just return it, no questions asked, although I bet you'll keep it. It's that good.
Duke, Thanks for coming back to me. That sounds like a nice flat response, but it is of course room specific, and not always achievable. You are right that since multiple subs give a flatter response over a far larger area, the potential for equalization is even greater. So I guess the right answer is to get the basics right by using more than one sub, and not shy away from some smart equalization either, particularly now that units like the Antimode 8033 are so easy to set up, and so cheap.
Hence the need for a low output impedance (which is a different way of saying the same). If the damping factor is too low, the frequency response becomes heavily load dependent, with potentially exaggerated bass or high frequency roll off (or other anomalies). Typically, this is not a problem with the better solid state amplifiers, but it is with tubes. Perhaps that is why some audiophiles like them. EDIT: sorry this was a response to an earlier post about the need for a high damping factor.
The show is pretty easy in easy out. Frontier Airlines " cheap flights now on sale " to DIA then $35 shuttle to Marriott. There are other hotels close by that are cheap to stay at.
I am going to be in the Bricasti Room 7013. Managed to get a pair of Wilson Benesch Evolutions to take to the show. Should sound great, I have a good history at the show. In another room, the Larkspur Wilson Beseech will have a pair of the Torus Infrasonic Generators. Or as Jonathan Valin said "
"Strokes of genius are rare in any field, but I think Milnes’ Torus qualifies”
The amp I supply with the Swarm has a single band of parametric EQ, but most people don't use it. The only time I've used it has been to extend the very bottom end a bit when all of the modules were in sealed-box mode, in a situation where we really should have left some of the ports unplugged but the customer insisted they all be plugged. We used a real-time analyzer but didn't save any of the curves. I haven't heard from anyone who has made measurements with the parametric EQ in play. I have heard from multiple customers reporting +/- 3 dB in-room across the bass region, with the -3 dB point clocking in a bit south of 20 Hz, without EQ.
One of my customers had been using a Meridian processor that had been professionally calibrated for his previous sub. He reset all the filters to flat and called in the technician after he had set up the Swarm. After making his measurements, the only thing the technician did was adjust the level a bit. No further equalization was needed. Apparently the technician said he'd never seen anything like it, and he'd been doing this for many years.
But it's not either/or! I am sure the Swarm would work very well with EQ, especially something well thought-out like the Antimode, in part because the spatial variation (change in frequency response at different locations) is greatly reduced by the distributed multisub configuration.
Duke, Your Swarm system is indeed interesting and sounds like the theoretically correct solution, even if one with rather a lot of boxes in the room. In my case, I think I will continue to save for a second PV1d, used with the Antimode, as a domestically acceptable compromise (the big stats have already been pushing the boundaries). Did you ever compare (and measure) your Swarm used with room equalization?
Soundsrealaudio…I actually considered the RMAF this year since I haven't been to one of those things since around 1987 (NYC Stereophile show). Hmmm…also, although I am very kind at all times (well…sometimes I take a break from extreme kindness to punish someone for disagreeing with me), I wasn't kind to you at all 6 years ago simply because I wasn't there. Don't mistake other people for me as many have simply stolen my look and style to get free drinks or the chance to be the new James Bond.
Willemj wrote: "I have tried to imagine what is meant by fast or slow bass. It cannot be the speakers themselves for reasons that have been explained. My hypothesis is that what people are referring to is really the delay that is visible in waterfall graphs of bass response in real rooms: the reflected sound of room modes lingers on."
Yes!!
What the ear interprets as "slow" is all happening on the trailing end of the notes. It is ALSO showing up as a frequency response peak, as you are about to see (and, this is the key to the in-room bass puzzle):
Speakers + room = a "minimum phase" system at low frequencies, and what this means is, the time-domain response tracks the frequency response, and vice-versa! In other words, where you see a slow-decaying ridge of energy in a waterfall plot is also where the system has a frequency response peak!
It gets even better: If we fix the one, we have SIMULTANEOUSLY fixed the other! So if we improve the decay time via bass trapping, we have simultaneously improved the in-room frequency response. And if we improve the in-room frequency response via EQ or distributed multisubs or whatever, we have simultaneously improved the decay time!
So any talk about the bass "speed" of a small woofer vs a large woofer is coming from an incorrect paradigm. The correct paradigm is, the in-room frequency response is marching in lock-step with the in-room decay times. THAT is the only "speed" that matters in the bass region, and we can fix it by fixing the frequency response!
* * * *
In these internet forum discussions it can be hard for observers to discern which posts contain accurate information. I don’t open up my trophy case very often, but given the myth-busting theme Eric envisioned for this thread, I think it may be relevant: A subwoofer system I designed using the principles I’ve posted about in this thread received a "Product of the Year" award from a major magazine (The Absolute Sound, 2015). This doesn’t definitively prove that the principles I’ve described are correct, but it does raise the possibility. If so, then credit to my teacher, Earl Geddes.
I have tried to imagine what is meant by fast or slow bass. It cannot be the speakers themselves for reasons that have been explained. My hypothesis is that what people are referring to is really the delay that is visible in waterfall graphs of bass response in real rooms: the reflected sound of room modes lingers on. When I added a B&W PV1d subwofer to my Quad 2805 electrostats I was disappointed at first, even though the room is large. The bass did indeed sound slow and woolly - not at all like the bass that was coming out of the stats. When I added an Antimode 8033 dsp room equalizer the problem was gone, and over a pretty wide area. So it was not the speaker that as slow, but the sound. My take home lesson has been that room modes can indeed be a big problem. In a small room it is not a good idea to even try to reproduce deep bass. In a bigger room, with room modes at lower frequencies, the problem is less (the Schroeder frequency is lower), and equalization is easier and effective over a wider area. The second lesson is that dual subs are advisable, and preferably combined with a room eq system such as the Antimode 8033.
Very pretentious of you to assume you can simply enjoy music. How dare you.
Are you coming to the RMAF this year. I think we spoke about 6 years ago there. I had the Wilson Beseech Curves and deHavilland electronics. You were kind enough to give me some compilations.
Richard Vandersteen has an interesting twist on servo-feedback woofers in his subs, He employs feed-forward (in contrast to feedback) in them, compensating electrically for the known non-linearities in the behavior of his woofers.
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! 😛
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?
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 believe Meyer do this also (a microphone in front of the woofer).
The alternative to correcting for errors is to eliminate them by using a single layer large 4" short length voice coil in extremely tight tolerance massive long magnetic gap - very expensive woofers indeed!
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.
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!
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.
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 servo-controlled woofers in Rythmik subs are described as "stopping on a dime". I liken them to a high-torque engine---very responsive. They "track" the signal very closely; no overhang/overshoot, no bloat or plumpness. Lean and clean!
"the woofers in his Rythmik subs are servo-feedback controlled"
Exactly, because to maintain accuracy and to stay in pace with the "lighter" drivers in the mains, you need a near realtime (servo) feedback mechanism to modulate the movement of the heavier driver.
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.
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.
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).
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.
"...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.
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!
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.
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?
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