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.
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:
http://www.acousticfrontiers.com/guide-to-bass-optimization/?utm_source=CTA
Interestingly: AF is in Fairfax, CA, home to Fritz Speakers. I really have to go visit Fairfax!
And a link to two great articles over at sound and vision:
https://www.soundandvision.com/content/schroeder-frequency-show-and-tell-part-1
https://www.soundandvision.com/content/schroeder-frequency-show-and-tell-part-2
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.
http://www.acousticfrontiers.com/guide-to-bass-optimization/?utm_source=CTA
Interestingly: AF is in Fairfax, CA, home to Fritz Speakers. I really have to go visit Fairfax!
And a link to two great articles over at sound and vision:
https://www.soundandvision.com/content/schroeder-frequency-show-and-tell-part-1
https://www.soundandvision.com/content/schroeder-frequency-show-and-tell-part-2
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.
124 responses Add your response
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. |
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. Duke dealer/manufacturer |
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. |
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? |
Thank you, willemj. 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 |
wolf_garcia 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, - Jonathan Valin, The Absolute Sound, 2007 Anyway if you make it you can try to be kind to me, even if you have to go against your nature. |
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. |
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. |
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. -gb- |
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. |
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 |
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. |
A slightly different take on woofer performance: 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. Hope this information helps. Robert - Star Sound |
@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. |
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. |