To appreciate what constitutes a good bass, one needs to experience a distributed subs system like the Swarm. Four relatively small boxes with 10 inch drivers placed against the four walls.
There's a lot more bass in a 6.5" driver than most of you think
One topic of discussion I often see new audiophiles touch on is whether to get larger speakers for more bass.
I usually suggest they tune the room first, then re-evaluate. This is based on listening and measurement in several apartments I’ve lived in. Bigger speakers can be nothing but trouble if the room is not ready.
In particular, I often claim that the right room treatment can make smaller speakers behave much larger. So, to back up my claims I’d like to submit to you my recent blog post here:
https://speakermakersjourney.blogspot.com/2020/01/the-snr-1-room-response-and-roon.html
Look at the bass response from those little drivers! :)
I admit for a lot of listeners these speakers won’t seem as punchy as you might like, but for an apartment dweller who does 50/50 music and theater they are ideal for me. If you’d like punchy, talk to Fritz who aligns his drivers with more oomf in the bass.
I usually suggest they tune the room first, then re-evaluate. This is based on listening and measurement in several apartments I’ve lived in. Bigger speakers can be nothing but trouble if the room is not ready.
In particular, I often claim that the right room treatment can make smaller speakers behave much larger. So, to back up my claims I’d like to submit to you my recent blog post here:
https://speakermakersjourney.blogspot.com/2020/01/the-snr-1-room-response-and-roon.html
Look at the bass response from those little drivers! :)
I admit for a lot of listeners these speakers won’t seem as punchy as you might like, but for an apartment dweller who does 50/50 music and theater they are ideal for me. If you’d like punchy, talk to Fritz who aligns his drivers with more oomf in the bass.
Showing 17 responses by pirad
@erik_squires " To appreciate what constitutes a good bass, one needs to experience a distributed subs system like the SwarmNot at all universally agreed to. https://www.soundandvision.com/content/are-you-putting-subwoofers-behind-viewer " The author has no idea how distributed bass works. Both Geddes (PhD thesis on bass) and Welti (Floyd Toole’s Harman lab) found in their research that key to distributed bass is asymmetric placement. Geddes believes three sources is enough: one in the corner, two others haphazardly against other walls. Duke LeJeune, Geddes’s coworker and constructor of the Swarm, adds the fourth source. There is no point adding more sources. Phase switching is not really part of the concept. Digital corrections of the whole system can be applied, but already the haphazard placement does most of the job. Digital corrections using counterwaves, such as those used in Kii3 or D&D, don’t really work below 50-60 Hertz. To battle complex phenomena like room modes, randomness is the most optimal way. Here, one can see easily, what problem room modes can be computationally: hunecke.de | Room Eigenmodes Calculator |
One more interesting concept is dipole bass, proposed by Siegfried Linkwitz in his LX521. The subs are v-frame dipoles and the side wall modes are minimized by cancellations. The bass is incredibly clear and tight. Finally, one can put the single sub next to his listening position to get at least one good spot with it. |
@erik.squires You wrote quoting me: " 02-01-2020 8:32pm >>When you EQ one sub, what you effectively do is ameliorate the modes situation at one spot (eg. your listening position) and make it worse elsewhere. It is easier to place the sub next to your armchair and delay it.<<
Never said that distributed bass is the one possible truth. I use it in home theater applications. I listen to music on dipole speakers with dipole bass. The whole issue of "room EQ" is for a longer discussion. One thing is to EQ the shortcomings of a speaker ("flattening the anechoic response"). Totally another is trying to EQ the room reponse. Let me quote Floyd Toole, in this AES paper: www.aes.org/tmpFiles/elib/20200201/17839.pdf "For decades it has been widely accepted that a steady- state amplitude response measured with an omnidirectional microphone at the listening location in a room is an important indicator of how an audio system will sound. Such measurements have come to be known as generic “room curves,” or more specific “house curves.” That belief has a long history in professional audio, and now it has penetrated consumer audio with stand-alone products and receivers in- corporating automated measurement and equalization capabilities. The implication is that by making in-situ measurements and manipulating the input signal so that the room curve matches a predetermined target shape, imperfections in (unspecified) loudspeakers and (unspecified) rooms are measured and repaired. It is an enticing marketing story. " "2.4 “Room Equalization” Is a Misnomer It is a bold assertion that a single steady-state measurement in a room—a room curve—can reliably anticipate human response to a complex sound field. Time-windowing the measurement is useful to separate events in the time domain, but these too ignore the directions from which sounds arrive. Human listeners respond to these cues, in some detail, and they exhibit skills in separating room sound from the timbral identity of loudspeakers, and in adapting to different circumstances. This is, after all, what happens at live, un- amplified, musical events. This means that not everything measured is perceptually important, nor can our reaction to such sound fields be constant, we adapt . The simple measurements therefore cannot be definitive. "
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" @erik_squires 02-01-2020 4:31pm The Swarm, when sealed, goes down to 18HzImpressive! I’ve gotten flat response to ~ 16 Hz with a single sub. Repeatedly. Not boomy. " I wrote before, that I stood once next to the 16Hz organ pipe and all I could feel was wind. I added a PS to my previous post above, repeat here: "PS. I should add that if you can hear sounds under 20Hz, you are likely to be an elephant. The human experience under 20Hz is rather vibration permeating various body parts. If you play test sounds under 20Hz and insist you hear them, then something is wrong with your subs. They play harmonics where they shouldn’t be. This test actually shows faults in the construction. Try these tests: The Ultimate Bass Test | Ultra Low Frequency Range Test " |
I have built both dipole and distributed bass systems. Dipoles are great for any kind of music down to the bass guitar low E (40Hz). Under 30Hz the experience is not impressive. The Swarm, when sealed, goes down to 18Hz. With the ports open even lower, but it gets kind of boomy. The sound is powerful but not so clear and natural as from dipole bass. I would say if classics, pop and jazz are your thing, go for dipoles. If you are a basshead or need to shake your home theater, distrubuted sealed boxes will deliver. PS. I should add that if you can hear sounds under 20Hz, you are likely to be an elephant. The human experience under 20Hz is rather vibration permeating various body parts. If you play test sounds under 20Hz and insist you hear them, then something is wrong with your subs. They play harmonics where they shouldn’t be. This test actually shows faults in the construction. Try these tests: The Ultimate Bass Test | Ultra Low Frequency Range Test |
@noble100 Thank you. I started the audio journey as a hobby several years ago. I bought licenses from Linkwitz to build his LX521 and from another source to build the distributed bass. Then I moved to my own designs. It is still a hobby, but my systems play at some interesting places. I don't think I'll be quitting my daytime job yet ;) |
Distrubuted bass addresses room modes, probably with more success than other solutions. Not sure what we are discussing here with respect to infrasounds (<20Hz). People can’t hear them, unless they are pure sine waves at big volumes. No concern for music, really. The movie theater experience of simulated earthquakes, explosions or thunderstorms is best served with bass shakers, like Clark Synthesis. There is also a niche in crowd control, where infasounds can be used to incapacitate people. A controversial and dangerous method, never really used in democracies (resonances in the respiratory tract that make breathing difficult). |
@twoleftears Your quoted the Positive-Feedback report "Description of the Magnepan subwoofer accompanying the "condo" 30.7. "The bass unit was about 3 feet tall and about 1 foot wide. The cabinet or structure consisted of a V shaped open baffle with 8 total drivers—4 vertically mounted dynamic cone woofers on each side of the V. These woofers were approximately 6.5 inches in diameter. Though there has been several dynamic cone dipolar designs attempted before, Wendell commented that this was a unique design that utilizes DSP and would eventually be patented. Yes, I said DSP! Though Wendell used the term "dipolar" for the bass units, I was told that the key design elements were the dual array and open baffle mounting along with the use of DSP. With this in mind, he also used the term "dual-dipolar" for the entire system to reinforce that this is a unique overall configuration and yet it still has the ability to be competitive with an all magnetic dipolar design." The bass solution decribed by Magnepan's top salesman as "unique" is not really so. All dipole speakers need EQ and since the cost of DSP fell down, it replaced discrete electronics. Siegfried Linkwitz (RIP) was a great proponent of dipoles, both in his corporate audiotech guru capacity and later as the "people's constructor". Go to linkwitzlabs.com His last design LX521 is a four-way and DSP controlled dipole. You can still buy the license and plans for $150. Total materials cost, if I remember correctly, ca 2k. His bass is a two-way V-frame, with two 10 inch dynamic cone drivers working in opposition. The phase is inverted on the back one, so the drivers work in push-pull configuration. That's what Wendell probably describes as "dual-dipolar". The LX521 is 10x cheaper and likely also 10x smaller than the 30.7 Magnepans. I would love to hear them in direct comparison. |
What is your definition of "steady state measurements"? Please note, this paper is from 2015, what changed since then in the area we are discussing? Dirac and others were there. Toole is not talking specifically about bass. He discounts the claims made by the proponents of so called "room EQ". And the inadequacy of "room" bass traps is self evident. How can you fit an elephant into a shoe box? |
Apparently we read different papers from two different universes, each with its own laws of physics. In your universe the definitions of physical states (eg. "steady state") follow circular logic. Let’s leave it there. As a parting note: "room EQ" makes poor systems sound better above Schroeder frequency, in the listening spot, by acting as an ersatz speaker correction technique. It does not improve systems designed properly from the start. That’s how it works in my universe anyway. Toole never really studied distributed bass, he left it to Welti. Geddes had the last word though. He also allowed bass EQ in some circumstances and so do I after him. www.gedlee.com |
There is no complexity to distributed bass. Place three similar subs randomly along the walls. The flatness of frequency response is irrelevant under 20Hz. Actually 18Hz is often a safety cutoff point for infrasounds, especially if you use vinyl. Good sub amps (like Dayton SA1000) have this feature. Sound traps need to be very very big to be effective at low frequencies. Anechoic chambers measure them in half wavelengths, and 20Hz wave is 55' or 17 meters. When you EQ one sub, what you effectively do is ameliorate the modes situation at one spot (eg. your listening position) and make it worse elsewhere. It is easier to place the sub next to your armchair and delay it. But of course everybody is free to choose his bass ways. In the end it is in the ear/brain of the listener. |
You write in your comments to Toole: "It’s 2020, who on earth uses steady state measurements?? " Toole does not give a definition of "steady state" in this paper, the readers learn it in EE101. Lacking that , some believe it is better to negate a simple concept like that because it sounds stale in 2020. The rest is just a consequence. |
For those interested in "room EQ", including bass, this is an interesting discussion that Floyd Toole joined and argued for multiple subs. It's fairly long, so for those with limited time I quote below relevant excerpts from dr. Toole's contribution. https://audiosciencereview.com/forum/index.php?threads/an-enticing-marketing-story-theory-without-measurement.7127/ ..." Below this [transition] frequency judicious equalization can be used to address individual prominent room resonances, but it is only functional at the point of measurement - the prime listening location. All other seats will be different. This is the reason why multiple subwoofers are advantageous, along with the greatly increased efficiency. The one area where EQ is unquestionably needed is in the bass, below about 400-500 Hz - room modes and adjacent boundary effects. It is necessary to attenuate resonant peaks, avoiding filling narrow acoustical interference dips. With multiple subwoofers it is possible to attenuate room modes and for the EQ to benefit more than a single listener. It is not difficult, but not everybody does it. Other mistakes result from trying to "fix" non-minimum-phase ripples in steady-state room curves. EQ at mid and high frequencies should be broadband "tone control" kinds of spectral balance adjustments, but too many systems think they know better. With bass performance accounting for about 30% of our overall factor weighting in sound quality assessments there is work for EQ at low frequencies - at least for the prime listening location. The fundamental problem is that all bass sounds are propagated through a three-dimensional acoustically resonant chamber - the room. There is no dominant "direct" sound in the normal sense because at all resonance frequencies the energy builds at a rate determined by the Q, and correspondingly decays. This behavior is different at every location in the room, meaning that multiple listeners do not share the same bass experience. To address the needs of multiple listeners multiple subs are powerful assets in attenuating room resonances and thereby reducing seat-to-seat variations. With signal processing in the signal paths to each of the multiple subs room modes can be made to almost disappear, certainly pushed well below thresholds of detection (e.g. Harman's Sound Field Management). Section 8.3 describes elaborate research on this topic, one finding of which was that active multiple sub solutions were better than necessary at attenuating room resonances - a nice result. Because humans tend to ignore ringing - now there was a surprise - even relatively crude frequency response smoothing at bass frequencies can be greatly beneficial. Any woofer or subwoofer I have ever encountered does not change its power response "vigorously" - they are minimum-phase systems that are quite well behaved. However, room modes/standing waves do change dramatically with location of the ears or mic. That is the problem to be addressed. Mode cancelling/attenuation using multiple subs greatly simplifies the situation, but only when the budget allows. Good news is that with multiple subs the total system efficiency rises, so they can be smaller subs. My present system uses four subs in a sound-field-managed configuration. There are no "booms". Bass is exceptionally "tight", and there is no audible evidence of being in a small room in what is heard at low frequencies - no measurable or audible resonances. In my room with four small SFM processed subs fhere are no audible modes in the sub range - the room is "gone", leaving only deep tight bass No bass traps required. Not everyone realizes that multiple subs are highly efficient - more small subs are vastly preferable to a single monster sub. ...There are passive multi-sub solutions for rectangular rooms: Welti, T.S. (2012). “Optimal Configurations for Subwoofers in Rooms Considering Seat-to-Seat variation and Low-Frequency Efficiency”, Audio Eng. Soc. 133rd Convention, Preprint 8748. The core of the problem is resonances in small rooms. Bands don't play in small rooms. A real drum energizes a certain set of small-room modes, giving it a room-modified sound. The same thing happens with a single woofer in the same location. Different small rooms would yield quite different real and reproduced drum sounds. The notion of multiple subs and EQ is to neutralize the contribution of the room to what we hear, so that we have a better chance of hearing what the mic picked up and the recording engineer heard. Seemingly endless promotion of "room EQ" algorithms - a for-profit exercise - is partially responsible, aided by human nature which is inclined to believe a good story. It is an ingredient in "faith based" audio - if you believe it, you just might hear it. Even though some EQ exercises "sound similar" does not mean that any are as good as they could be - perhaps the important similarity is at low frequencies."...
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