Talk:Subwoofer/Archive 1

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Location of subs in home audio

"Physical separation of subwoofer and "satellite" speakers not only allows placement in an inconspicuous location, but since sub-bass frequencies are particularly sensitive to room location (due to room resonances and reverberation 'modes'), the best position for the subwoofer is not likely to be where the "satellite" speakers are located. For greatest efficiency and best coupling to the room's air volume, subwoofers can be placed in a corner of the room, far from large room openings, and closer to the listener. This is possible since low bass frequencies have a long wavelength; hence there is little difference between the information reaching a listener's left and right ears, and so they cannot be readily localized."

I don't agree with what is being claimed above. Placing a sub in the corner with the aforementioned "satellite" system will often lead to localization due to a comparatively high crossover frequency to the sub. Because satellites tend to be small, they cannot reproduce low frequencies well, so the sub often takes on higher frequencies than it should. Just two paragraphs below there is info claiming the same. I am proposing a change of this sentence:

"Physical separation of subwoofer and "satellite" speakers not only allows placement in an inconspicuous location"

to

"Physical separation of subwoofer and the main speakers not only allows placement in an inconspicuous location"

Crossover

What is "crossover" supposed to mean? It was a redirect to electronic filter, but most of the links were talking about chromosomes. -phma

The crossover is a filter which splits the signal into frequency bands, each band going to the apropiate speaker.

I don't agree with the following sentences:

"People who are accustomed to bass in home audio systems and car audio many times think that the subs in a concert PA system aren't putting out that much." More like I agree with the statement but i do not agree with the explination given in the article which is wrong.

First, if you look at the Fletcher and Munson equal loudness contours you'll see that the more the SPL rises, the bigger the low freq. sensation. So if you turn the volume up without altering the eq settings or without using a loudness control you'll notice that the bass becomes louder and louder, and if you turn down the volume, the bass starts to disappear.


Well PA systems are putting a lot more than home and car audio subs and with a lot LESS distortion. Cheap home/car audio systems are putting a lot of distortion into the sound which are mainly harmonics and intermodulation of it's poor transient responce. These are superior in frequency and if you take a look at the Fletcher and Munson contours you can understand why the distorted signal will sound much louder, although if you are to measure it with a SPL meter you'll get the same reading. For example a lot of people think that 50Hz it's not such a low frequency. That because if you put a 50Hz sine wave through a low quality system it will sound loud, more like a buzz than a hum ("hmmm"). And the more you turn up the volume the more the buzzier it gets due to amplifier clipping and driver distortion (which rises 8 times when doubling the power (due to electromagnetic non-liniarities) or more if we add excursion related problems, cone deformation, and others) Comming from a good system, 50Hz will not give much to the ears instead will give your body a massage if played loud enough and will move your furniture for free :)

PA systems are handled (or should be handled) by professionals who are doing their best and the systems will sound correctlly and well tonal balanced. That's why they do not appear so loud than a cheap boom-box with it's bassboost set to max and with it's speakers bottoming out at each bass note.

(sorry for my bad english)

Legal Issues

These are a pain in the *ss, and we need to say so (in an NPOV manner of course). Walls of houses and flats are not designed to block these sort of frequencies, and (in the UK at least) complaints about domestic noise are rising. -- Tarquin 17:47 Feb 15, 2003 (UTC)

I hardly think the fact that some users of a piece of tech use it irresponsibly or in contradiction to local law is relevant. I'm sure that could be said of anything. Shall we add a note to the Automobile article that some people speed? Sapph 03:46, 20 April 2006 (UTC)
In some cases, it's quite difficult to get full use out of a subwoofer without being 'irresponsible'. Because, as said, most places aren't designed to block such a mass volume of low frequency sound. And I have no fact, but in my experience, most people use subwoofer in contrast to law, rather than within the law. They just create a huge irritance to most anyone and everyone else in the vicinity. Peoplesunionpro 22:57, 20 December 2006 (UTC)
Yeah, let's ban subwoofers, but not handguns. Subwoofers kill people.209.29.93.15 (talk) —Preceding comment was added at 09:01, 16 February 2008 (UTC)

Article clean up

I tried to clean up some of the writing in this article, but it seems a little unfinished. Should it be marked for revision to conform to the almighty higher quality standards?

Specifically, the equations in the last paragraph needs to be formatted. Thanks to all those who contribute to the page. =) Dept of Alchemy 06:03, 2 May 2006 (UTC)

citing

Many speakers were capable of emitting subsonic sounds or were powerful bass drivers before the 1970s, like Cerwin Vega in the 1950s. Citation is needed.RCHM 01:43, 10 October 2006 (UTC)

This article needs help

This article needs to be rewritten becuase of the non factual common audio misconceptions about subwoofers. A good example is woofer speed directly linked to cone weight. This is untrue and is related to the inductance of the coil. See bellow link. http://www.adireaudio.com/Files/TechPapers/WooferSpeed.pdf

Suspension non linearities with Square cones are not a big factor in distortion, the reason is they reinforced the corners is because of the sorround tearing.

There is more I just have to read it again. —The preceding unsigned comment was added by 216.98.239.15 (talk) 20:38, 10 December 2006 (UTC).

This article is also pretty biased, as one dickhead keeps deleting all kinds of information that is relevant, such as the effect of low-cost subs, kit subs, and other manufacturers. This article, like other hi-fi articles gets too subjectivist, and hides from real testing like that done by Tom Nousaine. Quit with the "high-end" and personal preference crap already. There is more to the industry, market and issue than was included. Sounds like the editor is favoring certain companies and philosophies...not objective writing.

There is no question about this article needing help. For example, the multi-piece Bose system shown does not contain a subwoofer - it contains separate(d)low frequency transducers (speakers) that they may reproduce frequencies close to or equal that of some subwoofers. In any case, due to the high crossover frequency, they are not subwoofers. Many quality two and three-way speaker systems can go down to 20 Hz, but that doesn't make the LF driver in the box a subwoofer. Taking the 12" driver out of a two way speaker system and putting it in its own enclosure does not qualify the 12" driver as a subwoofer. Neither are the other speakers in a multi-speaker system (always) called satellites, since that makes the supposed subwoofer the main part of the system which it is not. A subwoofer is an additional speaker system designed to reproduce very low bass frequencies, the key words being "additional" and "very low". It is a "fifth wheel" not a main reproducer of sound. Additionally, an active subwoofer is one that has a separate amplifier, not a "built-in" amplifier. A passive subwoofer is driven by the combination of left and right speaker outputs.66.191.203.186 (talk)

Other than being wrong on a number of points, you are right. The article does need help, but it needs help from somebody with more all around knowledge of subs. I'd like to show you a subwoofer based on 12" speakers that really kicks... and I'd like to see you disprove the fact that Bose called their little black LF unit a subwoofer. You don't appear to understand active vs. passive or how amplifier outputs work. Finally, if you don't like the imprecision of the word satellite, your work in the world is cut out for you—everybody uses it wrong. Binksternet (talk) 14:13, 27 July 2009 (UTC)

article should discuss teenager misuse of subs

It's not just teenagers, though. It's also so-called "adults." These pieces of shit are making other lives miserable, and that's exactly what they want to do! Their subwoofers are vibrating people's apartments (such as mine, and other residents and tenants for miles around), vibrating and shaking windows while riding in their mobile, acoustical-terror machines, making spring and summer, and even fall, which are supposed to be the nicest and most tranquil and calm times of year, into misery. If you scoff at the term "accoustical terrorism" it is very much real. For just one example, here is an example from Wikipedia's Manuel Noriega article: Noriega fled during the attack and a manhunt ensued. He finally turned up in the Apostolic Nunciature, the Holy See's embassy in Panama, where he had taken refuge. U.S. troops set up a perimeter outside this building, as any direct action on the embassy itself would have violated the customs of international law (and perhaps treaties to which the U.S. was a party at the time as well). The troops guarding it used psychological warfare, attempting to force him out by playing hard rock music, like Nothing's Gonna Change My Love For You, outside the residence,[1]... Now, going back to the situation on the streets of America, the United Kingdom, and elsewhere. The vast majority of these "music lovers" have air-conditioners in their cars. Why don't they use them, instead of sweltering in the stifling heat? I mean, besides the fact that they have very little logic? Well, it's because these sociopaths are so hateful of people, they'd rather suffer and swelter and sweat in the heat than be nice and dry with the windows shut and their air-conditioners on, so that they can be cool, dry and comfortable, if it means that they can bring misery to people (such as pedestrians, people in other cars, people at work, people who work third shift and must sleep during the day, and those at work), so that these victims of selfishness can't concentrate, sleep, THINK. Of course, that's REALLY the reason for subwoofers, ISN'T IT... HA! What a joke! They call themselves "AUDIO ENTHUSIASTS!"

Slater79 00:04, 3 June 2007 (UTC)

Wow man, you're making it sound like subwoofers are ruining modern society. In truth I think its that the people who get noticed are the obnoxious ones. 72.226.184.52 (talk) 22:47, 27 February 2008 (UTC)

always hear sound

just got ipod dock mp3 player with sub woofer and it always makes loud sound even when playing music softly is this right —Preceding unsigned comment added by 84.71.1.185 (talk) 22:12, 25 December 2007 (UTC)

Sounds like it's faulty, but this is not the right place for such issues. The help desk is better on Wikipedia, but it's a poor fit even there. ww (talk) 05:04, 28 May 2008 (UTC)

RMS ratings, types of cones etc.

I would like to see this article expanded dramatically. Subwoofers have been around for at least 30 years and there is little information readily available for those who would like to learn more about them. The article only briefly touches each of the areas such as the advantages/disadvantages of different types of cones and which ones would work better or give a better response time. If someone were interested in purchasing subwoofers for their car, this article would help them very little (if at all). I found only one or two other articles online that provide information that actually explain the type of woofer/amplifier that would work best, and why it would.

I really think there should be a section that discusses what type of amplifier would work with what type of subwoofer the best. This involves the CLASS of it, H/L pass frequencies, types of connectors, and surge/overload protection. Also, it should include how many CHANNELS would be needed for how many speakers/woofers etc. 12.215.147.98 (talk) 04:36, 21 January 2008 (UTC)X

454Casull (talk) 08:15, 15 November 2008 (UTC): I don't believe that this article should be a reference for one looking to choose a sub for their car. Not only will the scope of this article expand to gigantic and difficult-to-update proportions (not what any lay person is looking for), there's just too much opportunity for bias. Besides, there are tons of resources for choosing subs for any application.

+1. I don't think we need a buyer's guide in this article. It's enough to explain the basic concepts in brief, and let the more curious reader investigate further on their own. In particular, trying to put in a section that matches amplifier to subwoofer would start out wrong and suck harder with each new attempt to fix it. The problem is that whatever notional amp/sub pairing you think you've nailed will change with placement near boundaries, with arrays of more than one subwoofer, with ANY kind of retuning of the box. In a car, the moment you roll down the windows your amp/speaker pairing gets wack. There's no one right answer--never has been and never will be. Binksternet (talk) 19:13, 15 November 2008 (UTC)

Problems

There is way too much subjective, infactual, biased and unreferenced fluff in this article that it isn't funny. I have made some fairly major edits and flagged it as such. Noodle snacks (talk) 12:39, 19 March 2008 (UTC)

I agree. The article could use a rewrite with a strong hand. For instance, the lead gets off the tracks right away talking about driver sizes when it should only mention frequency ranges, the defining characteristic of subs. Binksternet (talk) 16:59, 19 March 2008 (UTC)

distortion in subwoofers

Intermodulation distortion increases with excursion and nonlinearities in BI with voice coil movement and suspension mechanics. Noteing this is hardly subjective or irrelevant. In the context of high excursion subwoofer drivers, it is clearly relevant. The pooint here about the psycho-acoustic effect of creation of pseudo low frequency sound is also relevant to quality of output from subwoofers.

It's important to note and should probably be in the article, that the effective output range for nearly all subwoofers is several octaves (especially when real crossover slopes are understood) and so IM distortion is not easily dismissed.

All the points in thsi article bear on subwoofer output quality and the proportionalities which apply (eg, greater excursion needed with smaller drivers at constant output, smaller drivers require greater excursion for constant output, ...).

So I suggest the para be left in. Perhaps reworded for greater clarity if necessary -- though that's not easy to do -- or to include more coverage of some particular point. Eg, small drivers require considerable effort to get equivalent quality output. ww (talk) 23:21, 19 March 2008 (UTC)

The problem isn't the inter modulation distortion statement itself, however the talk surrounding it (regarding cone size vs excursion), etc was highly subjective and not really all that accurate (for example the adire XBL^2 motors are able to achieve high excursion with low inter modulation distortion). By "not really an issue" I was was simply referring to the fact that sub woofers are not often producing mixed, in-harmonic signals of similar amplitude and hence are unlikely to produce audible IMD, especially when masking from the remainder of the system is taken into consideration. Talk about contributing factors to distortion is probably a good idea, but it needs to be concise and mention all types. Noodle snacks (talk) 23:34, 19 March 2008 (UTC)

Distortion of all types (IMD, harmonic, port noise) should be given prominence in this article. The human hearing curve requires far greater power output to sound balanced and neutral at low frequencies which effectively pushes distortion artifacts into greater prominence simply because we can hear them more clearly, even if they are at a measurably lower SPL than the source signal. This characteristic will color subwoofer design as long as the human ear is involved in audition. Binksternet (talk) 06:18, 20 March 2008 (UTC)
The human hearing curve requires more power to achieve equal loudness, however boosting bass artificially beyond the original is not an accurate way to reproduce a signal, assuming that the playback level is the same as the recording. At lower volumes the ear is less sensitive to bass so compensation is useful, however the output requirements of the subwoofer are somewhat lessened. Bass levels are however a personal preference, and many listeners (arguably the majority) will have their subwoofer levels set above neutral volume levels. Do you think that discussion on driver distortion is really something that should be on the subwoofer page, or perhaps the "loudspeaker" page for example? What issues do you think are unique to subwoofers in contrast to other speakers?Noodle snacks (talk) 08:43, 20 March 2008 (UTC)
Boosting bass unnaturally is a widespread habit (and could be mentioned here in this article if there's a reference) but not at all what I was talking about. What I'm after is a discussion of the problems associated with getting normal low frequency performance from gear pushed to its design limits. Harmonic distortion in loudspeakers is at least an order of magnitude more important a factor when the frequency range of interest involves subwoofers. Because human hearing is less receptive to low frequencies, the subs have to be driven harder for us to hear neutral balance across the frequencies. This stresses the motor and creates distortion. Also, many compact subwoofer designs step firmly into distortion artifacts at high output power or at their lowest frequency, simply because of enclosure limitations. ("Small, Loud, Low: pick any two.") Electrical characteristics and human physiology combine to make subwoofer harmonic distortion artifacts more audible than they are in mid and high frequency loudspeakers. Ten percent distortion of a 30 Hz sine tone which you can barely hear is mighty strong at 60 and especially 90 Hz. This distortion is used positively in classic DJ designs like the Cerwin Vega Earthquake series; a model that measures very loud and satisfies its users because of the added harmonic content when pushed hard. On the other hand, there are subwoofer designs (for instance, the ones by Tom Danley (ex-Servodrive, now Danley Sound Labs)) that minimize distortion and preserve impulse waveform for the most accurate reproduction of the original signal. Binksternet (talk) 15:35, 20 March 2008 (UTC)
An encylopedia article shouldn't discuss the "importance of anything", for example, harmonic distortion being an order of magnitude more "important" is a POV and not suitable in that form for an encylopedia article. Human hearing is less sensitive at low frequencies (see Equal-loudness contour). Practically by definition, a neutral balance implies the playback system should have flat frequency response, not try and compensate for the equal loudness contour. Imagine a recording at 85db with a perfect microphone (flat frequency response and zero distortion), if you were then to play back that recording with the same volume at all frequencies, you wouldn't play the bass back louder than the reality. Subwoofers don't have to play louder than any other speaker for a given volume level. What is true is that the physical requirements of playing at a given playback level may be higher (greater cone excursion, lower sensitivity boosting power requirements etc).I have read papers which claim (under scientific tests), that harmonic distortion is often less audible in the bass region (as in inaudible above the fundamental), this psychoacoustic effect is used with the Waves MaxxBass plugin for example. If there are multiple points of view (which is often the case with psychoacoustics), then they should be referenced and presented equally. Discussion of driver design and distortion etc should be done from a concise engineering point of view; There are a great number of dubious sources as far as audio is concerned. Noodle snacks (talk) 00:20, 21 March 2008 (UTC)

<--- N, Your insistence that distortion (and its sources) is somethning that shouldn't be discussed is a odd. One of the schools of car subwoofers is interested in low distortion and the other isn't (SPL only, more or less). It's an important issue, even in the car community. All measurable, by the way and hardly subjective POV.

B makes an excellent case for the significance of comments in this article on the distortion question. Subs are not exempt from any of the laws of physics (and materials behavior, not POV) that apply to other drivers. That the human ear is progressively less sensitive to low frequencies is compensated for by the progressively increased power handling required of bass drivers. And with incresed power handling comes the various increases in distortion with excursion and stress (voice coil heating, suspension non-linearities, cone distortions caused by increased force applied by the voice coil, ...) all of which are worse with smaller drivers (at equivalent output). Our Gentle Reader deserves to be informed that the laws of physics are not suspended when purpose built driver/enclosure combinations are used for the lowest frequencies. To not mention this issue is a disservice to Him/Her.

So I repeat, this prar should stay in, perhaps better written, but the points deserve to be made. ww (talk) 02:52, 21 March 2008 (UTC)

I am well and truly aware of the laws of physics, and how they apply to loudspeakers. I not even suggesting that distortion shouldn't be discussed in the article and believe it is an important subject. The laws of physics are applied to difficulties with subwoofer distortion due to the higher excursion requirements and greater thermal power handling requirements of the system, not because you have to compensate for human hearing's lack of sensitivity to bass frequencies.
You are both getting mixed up with equal loudness contours. Yes, the human ear is progressively less sensitive at bass frequencies, but this does not mean that the bass should be artificially boosted to compensate for this. Imagine a natural sound with significant bass content (say thunder). When you hear this sound your ears have exactly the same sensitivity to bass at the same volume level as playback through a subwoofer. If the subwoofer volume was boosted in relation to the rest of the spectrum then the thunder would have more bass than naturally occurs. By your argument high fidelity speakers should have a frequency response which is the inverse of an equal loudness contour, not a flat response.
In short, I have no qualms about discussion of any type of distortion, and think they should all go in the article, but compensation for human bass insensitivity does NOT cause increased power handling requirements for subwoofers, insensitivity and greater displacement requirements do. Noodle snacks (talk) 05:43, 21 March 2008 (UTC)
Distortion products that are higher frequencies than the input signal are more easily reproduced by subwoofer drivers and more easily heard by the human ear, making their presence more audible than in non-subwoofer enclosures. Binksternet (talk) 06:00, 21 March 2008 (UTC)
The first statement there is probably fine assuming you mean subwofoer drivers produce more distortion than other types, but not always the case, it will depend on the drivers in question. The second statement is in contrast to saying you need more power because the ear is less sensitive and correct, assuming the distortion is present enough that masking doesn't hide it. 58.6.128.214 (talk) 06:06, 21 March 2008 (UTC)
Masking is another good subject to cover but not what I was talking about here. Perhaps I can augment my second statement with an example: Because you hear 40 Hz relatively poorly, 80 Hz fairly well and 120 Hz quite well (following the human hearing curve), this means that a normal amount of harmonic distortion of a 40 Hz signal coming out of a subwoofer will have the second and third harmonics (distortion artifacts) fall into areas of your hearing that are more sensitive. Subwoofers are penalized by the hearing curve in that the listener is more sensitive to the higher-frequency harmonics. On the other hand, harmonic tweeter distortion, when present, can be too high to hear at all. Binksternet (talk) 07:02, 21 March 2008 (UTC)

<--undent. Here are four sample subwoofer THD tests done at the same testing session with each subwoofer's results shown one above the other. There's a subwoofer from the state of Washington, one from Texas, one from Italy and one from Slovenia. All are powerful, expensive portable subs intended for live sound events. Each one was tested seven times, one test frequency each time, at a (fairly loud) level of 28 measured volts of clean sine wave amplifier power and the total harmonic distortion was charted using neutral test mic and a TEF machine. There's no indication on this chart about the relative strength of the harmonic timbre--no knowing if the distortion is primarily 2nd or 3rd order, for example. Harmonics up to the 12th are added together and charted as one total. This is a hard chart to read (Edward R. Tufte would hate it) but I'm just passing it along the way the TEF machine spat it out.

None of the pictured subwoofers could reproduce the lowest tested frequency without at least 50% THD at 28V signal level. One also had 50% THD at 32 Hz, while the others showed THD beginning to ease up at 32 Hz. One of the boxes showed its least distortion at 40 Hz; this was probably its designed low frequency limit. Two were least distorted at 79 Hz and one had its minimum THD at 50 Hz. There are some visible spikes in distortion; one box added 23% THD at 67 Hz, but had less distortion above and below that point. The granularity of this chart leaves room for lesser and greater distortion spikes that we can't see because there were only seven data points.

This shows how much more distortion becomes a factor as the frequency goes down. Binksternet (talk) 08:46, 21 March 2008 (UTC)

Made it a more manageable thumbnail size. Most live sound subs have very limited linear excursion, and response may not extend below 50hz (depending on the units in question), so I am not surprised that at a few hundred watts of drive at 30hz that they are distorting a great deal. I am not making an argument about subwoofer distortion however as I have stated numerous times now, I am making an argument about the need to boost sub woofer levels since the human ear is less sensitive (which is rubbish). Practically everything else I can agree with. Going back to the paragraph in question, as I have said, the problem was all the text surrounding the inter modulation distortion, not the inter modulation distortion itself! Noodle snacks (talk) 09:07, 21 March 2008 (UTC)

Here is a peerless XLS at 105db and 0.1% distortion (30db down == 1/1000th intensity). [2]. Which is an example of a subwoofer not audibly distorting and playing within it's design range and volume (105db~). Noodle snacks (talk) 09:15, 21 March 2008 (UTC)

The need to boost low frequencies is "rubbish" if the listener wants a natural experience. This is a POV. Such strictures fall away if the listener wants to have a synthetic experience. Another POV. This article will work best if it is neutral in tone and addresses all the expected subwoofer usages. Binksternet (talk) 15:50, 21 March 2008 (UTC)
To qoute you directly: "Because human hearing is less receptive to low frequencies, the subs have to be driven harder for us to hear neutral balance across the frequencies.". I was working under your assumption that neutral balance is what the listener wanted, not as the general case. I think discussion of linear and non-linear subwoofer driver distortion can be done without even mentioning the user's preferred playback level. It would seem odd however that a listener would want neutral undistorted sound, and their subwoofer 10dB above the rest of their system. As far as distortion is concerned, do you think a section is warranted with sections for linear (eg frequency response) and non linear distortion (eg. Inter modulation distortion), with discussion about what causes distortion and what it's effects are? Noodle snacks (talk) 23:28, 21 March 2008 (UTC)

Cleanup

I did some tidying up of the article but there is still work to be done, especially in the Home Audio section. Binksternet (talk) 19:18, 28 March 2008 (UTC)

Among cleanup tasks were the deletion of hidden comments. Such comments should be brought here to the Talk page. Binksternet (talk) 01:08, 1 April 2008 (UTC)
Hidden comments are fine by the manual of style Wikipedia:Manual_of_Style#Invisible_comments. They are also useful because they give contextual notes to other editors. The talk page is useful for broader issues but you spend half your time describing where the problem is. I will return them shortly (Since issues raised have just been deleted). Noodle snacks (talk) 10:11, 1 April 2008 (UTC)
I understand what hidden comments are good for. I am asking for discussion here on the Talk page so that consensus can be built. Binksternet (talk) 16:16, 1 April 2008 (UTC)
Noodle, Your most recent edit (1 April) has decreased the worth of the article by introducing some mathematics that will be opaque to almost all Gentle Readers. And replacing a prose description accessible to those Gentle Readers (or some of them -- the comment just above requesting information is an exemplar). Adding the mathematics, or a referral to the T/S article for the technically interested would have been more appropriate.
Your approach to this article is not the only possible one, just as there are different formulations possible for many issues involving physics and science generally (thermodynamics laws, for instance). As we are here at the boundary of some obscure (to most) physics / materials science and an active popular interest in an audio engineering approach, I feel strongly that we should choose that approach most likely to be accessible to our Gentle Readers. Your insistence is, I fear, decreasing the article's quality.
We should not continue editing unless some consensus is reached among the currently active editors. If we can't manage that, perhaps a referral to peer review or even the arbitration committee might be in order? Perhaps there are opinions from others? Binksternet, perhaps? ww (talk) 02:06, 2 April 2008 (UTC)
I would love to see this article be as comprehensive as possible to the average reader. I think that adding mathematical formulae is appropriate but replacing prose descriptions with maths isn't. Binksternet (talk) 02:53, 2 April 2008 (UTC)
However if prose descriptions are present, they need to be technically concise and accurate. What does poorly "coupling" actually mean? The stuff about human hearing sensitivity was incorrect, as previously established. (Subs don't need to be more powerful due to hearing sensitivity, not that subs don't need to be more powerful). —Preceding unsigned comment added by Noodle snacks (talk • contribs) 06:05, 2 April 2008 (UTC)

Phase dial on subwoofers

My contention is that by far the most phase controls on subwoofers are of the polarity inversion variety. I understand that there is a three-driver sub which includes phase switches yielding 60/120 degree phase changes (at certain listening positions) but I would guess that it achieves this via combinations of polarity inversion. Which specific sub models include a frequency-over-time or pure time function in their phase control? References needed. Binksternet (talk) 01:08, 1 April 2008 (UTC)

As per Wikipedia:Citing_sources#Text_that_is.2C_or_is_likely_to_be.2C_disputed The appropriate protocol is to either find a reference or flag the content with a [citation needed] or two, not to delete it outright. Noodle snacks (talk) 10:14, 1 April 2008 (UTC)
I see your reference is to a DIY continuously adjustable all-pass phase control device designed by Rod Elliott and published in 2004. Elliott himself says it is "very common in subwoofers" and boom, that's our reference. How likely is it that Elliott can see clearly how common the all-pass circuit is in subwoofers in general? All-pass circuitry for correction of home theater setups is mentioned here in 2004 but isn't evident in subwoofer product feature lists or brochures that I've been able to find. Even though Hawksford was publishing his all-pass solution for subwoofer/satellite systems as early as 1992,[1] I still am not seeing this control out in the marketplace as a switch or dial on the back of a subwoofer enclosure. In fact, in several subwoofers commercially available, the presence of an "All Pass" switch is simply the absence of a crossover filter or phase control of any sort.[2][3] In these products, the term "all pass" means full pass-through, a very poor choice of words. :(
Rod Elliot stated that variable phase control circuits are common in subwoofers, not that that particular type is. The rest is a moot point as far as that reference is concerned. There are now three references which state that the circuits are common. In my own experience they are also common, being present on the vast majority of active sub woofers I have seen. 58.6.128.214 (talk) 06:43, 3 April 2008 (UTC)
I have added five more references to state that they are common, since three wasn't quite enough to convince you. Here are some products (either amplifiers or complete subwoofers) that have continuously variable phase control (they don't make an argument, the references do):

Noodle snacks (talk) 07:16, 3 April 2008 (UTC)

I think that the common-and-garden polarity switch deserves its own section. Information regarding continuously adjustable all-pass circuitry (internal to the subwoofer, part of active 3rd party amp, DSP or crossover, DIY project box, etc.) should get its own header as well. Delay should be mentioned here, too... I don't know if straight delay adjustments taken to influence phase in the crossover region should fall under Phase control or under its own header. Probably its own header since straight delay would often be applied to the main speakers in order to line them up to the subs. Let's separate the topics. Binksternet (talk) 16:12, 1 April 2008 (UTC)
In regards to a recent edit under the Polarity header: The sentence "This configuration allows the subwoofer to either be in phase, or 180 degrees out of phase" might lead the reader astray. Phase is relative: something can be in or out of phase with relationship to something else. Binksternet (talk) 02:51, 2 April 2008 (UTC)
The sentence made the assumption that the default subwoofer phase was the reference. Noodle snacks (talk) 06:07, 2 April 2008 (UTC)

good article nomination comment

This article, in its current state, does not qualify. It has at least one gaping lacunae, namely indices of poor quality. Enclosure structure is not discussed (light weight, thin, enclosures interfering with quality performance), distortion issues are not discussed (though they once were), etc Until this issue is addressed on behalf of our Reader, the article will be of distinctly limited quality, certainly not of good quality. ww (talk) 05:13, 7 April 2008 (UTC)

We're closer to GA here than at any point in the last 9 months--before that I hadn't seen the article. Here's some notes for getting there: Stereo separation should be a subsection under Overview. Also under Overview should be distortion and construction discussion. For Applications I propose this hierarchy:

3 Applications

3.1 Home audio
3.2 Car audio
3.2.1 Non-circular drivers
3.3 Cinema sound
3.4 Concert sound
3.4.1 Concert subwoofer techniques
3.4.1.1 Aux-fed subwoofers
3.4.1.2 Directional subwoofers
3.4.1.2.1 Vertically arrayed subwoofers
3.4.1.2.2 End-fired subwoofers
3.4.1.2.3 Delay shaded subwoofers

4 Bass Shakers

That's what I'm imagining so far... Binksternet (talk) 06:05, 7 April 2008 (UTC)

Be Bold and go for it in my view. Noodle snacks (talk) 07:27, 7 April 2008 (UTC)
Seems reasonable to me. Note that my objection is not about application types, but rather to the inadequate conceptual coverage, on the downside of subs and sub designs. ww (talk) 16:33, 7 April 2008 (UTC)
Hierarchy reorganization is complete. Now it's time for people to write sections that cover construction, distortion, popular misuse and abuse, environmental complaints, etc. Binksternet (talk) 20:05, 7 April 2008 (UTC)


Stereo localization at subwoofer freqs

Unreferenced material on stereo separation was recently removed from this article. Since low frequencies are where the question of localization comes to the fore, where else would this material work? Its own article? Subwoofers themselves have been the subject of much conjecture and opinion regarding localization. Studies put subwoofer localization easily within even the worst home listening situations at frequencies down to 50 Hz at which point positive results disappear into chance. Given that subwoofers can be localized from 50 Hz up, some folks have stated that stereo imagery or soundstage benefits from each loudspeaker position having its own LFE capability. Others exert themselves to eliminate localization effects, an effort that would be at cross-purposes to full-frequency soundstage fans. At any rate, the localization question and its various answers can be elucidated best here, I feel. I don't have time to write it now but here are some of the refs I've found:

IN TWO DIFFERENT REVERBERANT REPRODUCTION ENVIRONMENTS William L. Martens, Jonas Braasch, Timothy J. Ryan] Binksternet (talk) 15:26, 10 April 2008 (UTC)

It would be important to differentiate between low frequency localization and that which contributes to sub woofer localization. Are the frequencies the same? how much distortion do the studies produce?Noodle snacks (talk) 09:47, 11 April 2008 (UTC)
Good question. Braasch is a fairly conservative and careful investigator; I'll try to figure out if he includes harmonic distortion, intermod distortion or port distortion in his research. Binksternet (talk) 17:23, 13 April 2008 (UTC)
Another article is "Loudspeaker and listener positions for optimal low-frequency spatial reproduction in listening rooms." by Dr. David Griesinger of Lexicon, main founder of LARES. Binksternet (talk) 03:23, 1 August 2008 (UTC)

Subwoofer oddities

Anybody object to the idea of a new section that briefly mentions unusual subwoofer projects? I have in mind several instances of subwoofer design taken to one extreme or another:

  • dB drag racing where a subwoofer is used as a piston to compress the air space within a sealed and reinforced vehicle interior. Current record is 180.5 dB.[4]
  • Danley Matterhorn: single subwoofer built out of a shipping container with 40 drivers mounted in a horn. Capable of 105dB at 250 meters. Its frequency response's -3 dB down point is 12 Hz.[5]
  • Rotary woofers: capable of sub-20 Hz tones.
  • Vibrator_(mechanical)#Industrial vibrators: low frequency vibration table (or shake table) for component testing.

Also, the current Bass Shaker section could be transferred to this section. Binksternet (talk) 17:23, 13 April 2008 (UTC)

I'm fine with it. More information is a good thing, especially for a encyclopdia claiming broad coverage. But I'll note that the rotary woofer design was referenced once in the context of the frequency range a sub woofer could get down to and has been deleted at least once. There's been a tendency to delete before discussion. I'm still waiting to settle the question about whether distortion in subwoofers (and ways to reduce it) can be restored to the article. ww (talk) 07:03, 6 May 2008 (UTC)

GA fail

I am sorry to inform the editors of this article that I am failing it. I have compiled a list of things to fix before renomination:

  • Per WP:LEAD, the lead should be three or four full paragraphs summarizing all the main points of the article.
  • A lot of sections and paragraphs have inadequate referencing. For example, the following sections have paragraphs without even one source: History, Construction and Features, Active, Home audio, Car audio, Non-circular subwoofers, Concert sound, Full-range system, Directional subwoofers, and Vertically arrayed subwoofers. Footnotes (or in-line citations) are necessary to help with verifying information.
  • There are a couple of "citation needed" tags that need to be addressed.
  • There are some Manual of Style problems, so the article would benefit from a copy-edit from a user who hasn't worked a lot on the article, as main editors of articles tend to miss these things.
  • Citations should be behind punctuation, not in the middle of sentences.
  • See also should be above References.
  • The references need cleanup and formatting. Template:cite web should help with that.
  • I think some of the links in the External links shouldn't be there. Check WP:ELNO for links that should be avoided.

Good luck with improving the article. Nikki311 01:07, 6 May 2008 (UTC)

Much of audio engineering, at least in loudspeaker design, is either common knowledge (eg, there's no need to source a statement that iron is a solid at room temperatures as everyone knows it to be true) or not addressed in academic publications. This is a commercial art / engineering practice. This particular aspect of the article is unlikely to meet WP standards.
Of more importance is that the article does not cover important aspects of the topic, such as quality metrics and guidelines to performance evaluation. This is important for readers given the degree of poetic writing in many product reviews. It is possible to, somewhat, to distinguish between poetry and useful information in a review. Our article should at least attempt to do so, and until it does, it should not make the GA list. ww (talk) 07:11, 6 May 2008 (UTC)

Problem with Vd formula

There needs to be a conversion factor added, or different units need to be used. Currently it claims that m^3 = m^2 * mm, which is wrong. Themania (talk) 13:04, 16 March 2009 (UTC)

References

  1. ^ AES E-Library: Asymmetric All-Pass Crossover Alignments by Hawksford, M. O. J.
  2. ^ Tannoy 5.1 Sub 15
  3. ^ Magnedyne LS-SUB-75
  4. ^ Pioneer Premier subwoofers and amplifiers used to create WorldRecord
  5. ^ Danley brings the Matterhorn to NSCA

why nobody states that almost 90 percent of all subs in hi-fi and even high end market are in no way suitable with playingback music and targeted at movie-related use. Only those by rel m and k and a very few others do have on top of thier sub product lines actually musical and sonic subs that suit well any hi-fi-hi-end system. —Preceding unsigned comment added by 77.35.39.236 (talk) 14:34, 1 March 2009 (UTC)

Permanent magnet doesn't have to be magnetic

Can the permanent magnet be not magnetic at all? I.E. jsut iron; then it would be much easier to home make a speaker to your own preferences. Daniel Christensen (talk) 20:12, 21 September 2009 (UTC)

Look; this cone and voice coil works when held up to anyhting iron: http://www.youtube.com/watch?v=_dJKh2MYIjo lol that's my video. Daniel Christensen (talk) 20:12, 21 September 2009 (UTC)

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