Audiophile quality powered subwoofer

[bdiament]

HI Gedlee,

 

I suppose then, that my experience is different from yours.

 

I'm not referring to phase differences with sine waves; I'm talking about wavefronts with real signals (i.e. music).

 

The test is precisely relevant because it removes the HF which you suggest is the reason we can localize. The test shows plainly, with low frequencies alone, that we can. Outdoors or in.

 

I've already mentioned in an earlier post, my experience in locating a hidden sub that was used in a quite elaborate system. Luck? I don't think so as my initial listening impressions, from the first few seconds of the audition, was that all the low bass was coming from behind me. What I could see behind me was a pair of large electrostatic panels being used for the rear center, in an elaborate surround system. When I continued to seek the sub back there, I found it behind one of the panels.

 

That's why I suggest the test. I would hope no one simply takes my (or anyone else's) word on what is reported in Internet fora or audio journals but that they would seek to listen for themselves (in as many different situations as possible) and then draw their own conclusions.

 

Granted, different folks have different sensitivities to different aspects of sound.

As I said earlier, my experience is that real life is stereo. All the way down.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

[toasties]

Barry, I'm not sure removing the high frequencies is a reliable test. In my experience because high frequencies are easier to localise, if you have a well integrated sub and main system the brain will recogise all the bass as coming from the location of the high frequencies. The brain hears several harmonics and localises the overall sound to the harmonics easier to locate, namely the higher harmonics. If you take away the high frequences that illusion can no longer occur and the brain will take it's cue from what's remaining, ie. the sub.

 

I think there is an issue where a single sub is two far from the stereo field, the result is a contradiction of where the bass sounds like its coming from (the main speakers) and where it feels like it's coming from (the sub), the illusion described above breaks down and the result is incredibly off-putting and very obvious in passages with considerable bass, and which explains the issue you described with a rear sub. But a single sub in the centre of the stereo field doesn't have this problem in my experience.

 

On the other hand, I would recommend two subs for the other issues discussed such as resonances etc. Having spent quite some time equalising subs in my room to achieve a perceptively flat response the task is a great deal easier with two than just one.

 

[bdiament]

Hi toasties,

 

"...I'm not sure removing the high frequencies is a reliable test..."

 

It is key because it will show that we don't need the high frequencies in order to localize a sound. We can localize on the bass alone. That is the point of removing the highs.

 

 

"...I think there is an issue where a single sub is two far from the stereo field, the result is a contradiction of where the bass sounds like its coming from (the main speakers) and where it feels like it's coming from (the sub)..."

 

When I hear subs far from the main pair, I hear the bass from the subs, not the main pair. If "it feels like it's coming from (the sub)", it is because we can localize the bass. The proliferation of the "place it/them anywhere" mantra from writers and even some manufacturers is in my view, why so many sub installations sound so poor and unintegrated with the rest of the sound.

 

Again, bass tends to radiate omnidirectionally, not nondirectionally as some erroneously suggest. In all directions is not at all the same as from all directions.

 

My suggestion is to try the test I mentioned. It is but one way of confirming we have no difficulty localizing bass. If we couldn't localize bass, it wouldn't matter; if all the arguments from the 'experts' on the web were correct, having subs "behind the couch" would sound exactly like having them next to the main pair.

 

But if you place them behind the couch, it sounds like the bass is behind you, where in fact, it is. It sounds like it is behind you because you are localizing the bass.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

 

[toasties]

I'm not sure we are disagreeing on that much. I agree that placing the bass anywhere in the room is not a good idea (besides, this seems to be based upon a desire to use room resonance to maximise slam, which isn't a good thing for music listening anyway).

 

On the other hand, if you place the sub the middle of the stereo field, feed it a mono signal and play bass only through the right channel, I, and I think most people, will interpret what they hear as bass coming from the right speaker. Likewise, play as bass sound only through the left channel, and I will interpret that as a single bass sound coming from the left speaker. This assumes a properly integrated system. Hence why I don't think that two subs are necessary to maintain a stereo field.

 

[bdiament]

Hi toasties,

 

I guess the only place our perceptions might be differing is where the bass appears to come from when a single sub is used.

 

If we can localize bass, as I have no doubt we (at least some folks) can, then it is important to keep the signal in stereo all the way down. Aside from it being easier to integrate stereo (which I'll differentiate from to two or more mono) subs into the room/system, this preserves stereo imaging throughout the frequency spectrum.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[Egon]

I think that the statement "We can't localize below 80Hz" is inaccurate. The correct statement based on available data should be "Almost no one can localize below 80Hz".

 

I tried to look up the original papers on which the statement is based, but don't have electronic access to the pdfs. As far as I can tell, it's all based on studies in the 1950's, and data was generated in both anechoic and live rooms. The best I could do was a quote from Tom Holman's book, "Surround Sound: Up and Running". Here's a quote copied from this site (which has more info):

 

http://www.audiodesignline.com/207401603?printableArticle=true

 

"Experimental work sought the most sensitive listener from among a group of professional mixers and then found the most sensitive program material (which proved to be male speech, not music). The experiment varied the crossover frequency from satellite to a displaced sub-woofer. From this work, a selection of crossover frequency could be made as two standard deviations below the mean of the experimental result from the most sensitive listener listening to the program material found to be most sensitive: that number is 80 Hz."

 

So if 80Hz is two standard deviations below the mean, then there could be a "golden-eared" outlier who can localize the subwoofer at lower frequencies. But 99.99% of the population can't. It seems almost predictable that someone capable of dissecting such minutiae of sound would become an audiophile, too.

 

[bdiament]

Hi egon,

 

Fortunately or otherwise, one can pick any perspective on anything in the world and find a web page or article somewhere that agrees.

 

So, on one hand we have a web article saying folks can't localize below 80 Hz. (The correct way to phrase it would be this "conclusion" is supported by the test they write about, with the listeners in that particular test.)

 

On the other hand, I submit I can take anyone off the street, blindfold them (with their consent of course ;-}), play them signals at the lower reaches of a good sub and they will be able to point to the sub with no difficulty.

 

80 Hz is the THX approved crossover for a subwoofer. While it might be okay for non-critical listeners seeking a cinematic experience that will shake their (personal) bottoms), in my opinion, this is at least an octave too high to achieve a seamless blend for a high quality music system. (I believe a lower crossover works better for movies too.) Personally, I've never heard a THX system that was remotely convincing. Exciting, perhaps but not at all realistic.

 

As I hope I suggested when I first mentioned it in an earlier post, I don't want anyone to simply take my (or anyone else's) word for this. Best to try the test as described and draw one's own conclusions.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

[Egon]

Barry,

I tried your test for myself at home today. I played a 60-70Hz test tone sweep, 10 second loop, 1 second per Hz. Sitting in my seat, it was just everywhere. I couldn’t tell where it was coming from until I started walking towards the sub and could feel the waves and my ears began to feel more pressure from the increased SPL. So I’m in the group without golden ears, but I still like music so I’ll survive. That’s on an SVS beast of a sub FWIW.

 

Now, to respond to your last post. You’re absolutely right, you can find lots of information on the web, and it’s important to check validity. My career (listening to music is just my hobby) is as a molecular biology research scientist, and I take critical analysis very seriously. In addition, I’m an author on multiple scientific papers and familiar with the word “conclusion”. It is not THE correct way to phrase this as a “conclusion”, it is A way. Alternative statements all with the same meaning…

 

The correct statement based on available data…

The correct conclusion based on available data…

The correct statement of conclusion based on available data…

 

I did my homework before my last post to see what data exists to support the 80Hz crossover. The reading I did convinced me that I don’t need to reinvent the wheel, no reason to do what’s already been done. I then found a site that summed it up neatly and quoted that rather than this literature review that follows that I could have written yesterday.

 

I welcome a critical discussion based on evidence, but won’t get into jawing back and forth over what we think might happen. These articles by folks on the web below seem to be reputable as determined by knowledgeable peers well-versed in the field (i.e. journal editors/reviewers). I invite you to examine their methodology and data analyses and determine what should have been done differently, and why their findings are not correct. I certainly understand that conclusions are subjective interpretations of objective data, and therefore not infallible.

 

I also hope that you will search the web for primary research articles supporting your point of view. I hold my belief until I see data that demonstrates it to be wrong. If you can find that data, I may change my mind. Not n=1 data from a potential outlier audiophile, but fully statistically significant data. This field of sound localization and psychoacoustics has been studied at least since Nobel Prize winner Lord Rayleigh’s Duplex Theory around 1900, so there must be a wealth of competing viewpoints over 100+ years.

 

The idea that we “feel” bass rather than hearing it from a direction seems reasonable in a poorly calibrated setup, so I can see the value in a 2+subwoofer setup where waves would arrive from right and left at the same time. I also believe there may be outlier audiophiles who can localize better than the general population. However, for 99.9% of us, I’ll submit to the belief that one properly calibrated subwoofer in a room with no obvious acoustical issues will do just fine.

 

I will propose to amicably agree to disagree, as I doubt this evidence will convince you. We’ve both got our different opinions based on whatever we base them on. Nonetheless, hopefully others on this forum will glance through the research and feel confident themselves that the numbers they hear regarding crossover and localization are substantiated by a body of peer-reviewed experimental evidence, merely concisely summarized on Wikipedia.

 

 

Borenius, J., ‘Perceptibility of Direction and Time Delay Errors in Subwoofer Reproduction’, Presented at79th Conv. Audio Eng. Soc., preprint 2290. Oct. 1985

 

(subscription only and I don’t want to post the .pdf here)

 

Abstract: It is generally assumed that the human ear is not very sensitive to the directional and possibly also to the time delay errors of these components. Not much research has been done on this, however. This paper deals with a study of these phenomena. It turns out, among other things, that the directional errors are generally not perceptible, or at least not disturbing, when the upper frequency limit of the subwoofer channel is less than 200 Hz. Fairly small time delay errors, on the other hand, are perceptible and disturbing especially in the reproduction of speech. Music signals are, in many cases, more tolerant in this respect.

 

Kügler, C. and Theile, G., ‘Loudspeaker Reproduction: Study on the Subwoofer Concept’, Presented at 92nd Conv. Audio Eng. Soc., preprint 3335. Mar. 1992

 

(subscription only and I don’t want to post the .pdf here)

 

Abstract: A stereo pair of full range loudspeakers and a stereo pair of loudspeakers reproducing the mid to high frequencies (satellites) plus one common low frequency sound loudspeaker (subwoofer) are compared. AB-AB listening tests were used to determine the absolute threshold of audible differences dependent on the parameters of subwoofer location and crossover frequency. The performance of the subwoofer/satellite concept is discussed from the theoretical and practical point of view, bearing in mind future multi-channel sound systems.

 

The Use of Subwoofers in the Context of Surround Sound Programme Reproduction. Journal of the Audio Engineering Society, April 1998, Volume 46, Number 4, pp. 276-287.

 

Available free at:

http://www.bbc.co.uk/rd/pubs/papers/paper_25/paper_25.shtml

 

(From results section): “Minor differences could be noticed occasionally but identification of a certain system was not possible, nor was it possible to assess whether or not a system was superior or inferior. The group came to the conclusion that, within the constraints of these specific tests, the six subwoofer arrangements and the reference full bandwidth main channel options were equivalent and interchangeable from the point of view of the listening experience. “

 

Detection of Subwoofer Depending on Crossover Frequency and Spatial Angle Between Subwoofer and Main Speaker. Audio Engineering Society Convention Paper Presented at the 118th Convention 2005 May 28–31 Barcelona, Spain

 

Available free at:

http://www.acoustics.hut.fi/research/cat/psychoac/papers/kelloniemiaes118.pdf

 

ABSTRACT

Since the direction of sound is not perceived at very low frequencies, it is feasible to use only one subwoofer for low frequency reproduction in multi-channel audio setups. A listening test was conducted to find the crossover frequency where the listeners begin to detect the subwoofer presence. The test was arranged in a symmetrical listening room using four pairs of speakers, arranged symmetrically in four angles to the front of the listener to equalize the timbres as well as possible in reverberant conditions. The detection judgement was done using a version of the two alternatives forced choice (TAFC) adaptive method, with which the 75% point of the psychometric function was found. With the used sound samples the crossover frequency could be set to about 120 Hz before the subwoofer became detectable. No correlation was found between the highest acceptable crossover frequency and listening angle when the angle exceeded 30 degrees.

 

 

 

 

[bdiament]

Hi Egon,

 

Thank you for the collection of links. Obviously it will take some time to go through them all and give them the time they deserve.

 

I'm glad you tried the test. It seems we will have to agree to disagree. No problem. Folks won't always agree and my experience is that different folks have different sensitivities to different aspects of sound. I find I can point to subs (mine are crossed over at 30 Hz) without difficulty and as I mentioned in an earlier post, I've found a hidden sub by ear in an unfamiliar but very high quality system.

 

In all instances, the rooms involved have been well treated acoustically. Either this or an outdoor setting assures the room itself is not a factor in localization.

 

I will report on any technical research I might find on the subject (when time avails). However, in view of the fact that you say you can't localize your sub, I don't see why any statistics that say otherwise would change what you hear.

 

Meanwhile, I thank you for this interesting dialog.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

 

[Egon]

Thanks for not taking offense. You're absolutely right to believe what you do based on your experience. Same for me, and for that reason, we each set up our systems how they work best for us.

 

In my room, the subwoofer isn't pointed directly at the listener; all sounds from it are reflections. Would that skew the results and make it less directional? It works for me, but may not be "best practice". I'm on this site to learn to do things better, and this may be a learning opportunity.

 

I really would be curious to see any evidence that supports a lower crossover. This discussion may end up costing me money if I have to buy a bigger amp to drive my speakers at a lower crossover. =-)

 

Happy listening!

 

[bdiament]

Hi Egon,

 

Not at all. Why would I take offense because you don't agree? (Oh, I almost forgot. This is the Internet. And this is audio! ;-}) I think differences are what make the world go 'round (if folks have the confidence in their own perspectives to handle them -- granted, not so common with Internet audio). And through disagreements, I find I often learn something.

 

Anyway, perhaps the reflections are altering how you hear the sub. I seek to eliminate reflections in the systems I set up - at least those that would arrive at the listening position within ~10 ms of the direct sound from the speakers, as these in my experience, do in fact obscure the information and smear timing cues.

 

The crossover frequency is chosen for the best match with the main pair. With my speakers, in my studio, that occurs at ~30 Hz. With no equalization (but with fully treated acoustics) the response is ±1.5 dB all the way down. In other systems I've set up, the crossover to the subs occurred at 40 Hz. I find it will vary with the capabilities of the main pair.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[firedog]

Good modern RC such as Tact and Lyngdorf also works in the time domain. One of the reasons the stuff is expensive.

 

My experience is that the vast majority of users think it improves the sound, even those who are skeptical beforehand

 

However, the best result would come from trying to acoustically improve the room first, and then use electronic correction.

 

[Shadorne]

The reason you can locate a sub is distortion and hearing acuity. Your hearing is extremely good around 1 Khz. The slightest distortion will give away the location of the sub. Most subs give out 20% to 50% THD anyway - there are very very very few good ones and they are very very expensive. If you have music playing through the mains then this will virtually always be loud enough for you to be unable to detect the location of the subwoofer unless you are sitting within three feet of it. There are one or two high quality subs with THD less than 1% and if you run these no higher than 60 Hz then you will probably be unable to detect there position (provided nothing rattles).

 

Remember your hearing at 20 Hz is terribly low in sensitivity compared to 100 Hz - we are talking between 30 db to 50 db difference in hearing acuity (depending on SPL levels)

 

[bdiament]

Hi Shadorne,

 

"The reason you can locate a sub is distortion and hearing acuity. Your hearing is extremely good around 1 Khz. The slightest distortion will give away the location of the sub...."

 

I'm sorry to disagree but this is an old argument and in my view, was just as mistaken when first offered as it is now. The reason we can locate the sub is the ear/brain are quite effective at detecting minute differences in the wavefront arrival time.

 

The test I suggested - using a low distortion sub, played at a low enough level to keep it from generating sufficient harmonics that those are what you hear - will demonstrate the fallacy of the old argument quite quickly. That low distortion sub is as easy to locate as a tweeter is.

 

This is completely unrelated to hearing sensitivity at 20 Hz. Obviously, if one can't hear a frequency, they're not going to have an easy time of locating it. ;-} If the sub can be heard, it can be located - at least by some folks.

 

The hidden sub I described in an earlier post was not distorting. It was providing clean low bass and I found it by no other method than listening. This, while music was indeed playing through the main pair, as well as several other pairs (fed from a computer). The rear center pair must have been 10-12 feet (2.5-3 meters) behind me and the sub was behind them.

 

 

 

[Egon]

Shadorne- I'm unfamiliar with some of what you said and need it explained in more layman's terms for my simple brain. I agree with your statements about human hearing, they're well proven. I'm not familiar enough with what THD is. I know it stands for total harmonic distortion, but not really sure what that is. Are you stating that although my sub is crossed over at, say, 80 Hz, it's still putting out an appreciable level of sound at 1000Hz? I don't know the ins and outs of speakers like others here and recognize an opportunity to learn.

 

And Barry- what do you mean by wavefront arrival time? Is this the phase? I'm picturing a wave, going up and down with its amplitude and frequency, and say that wave at a given frequency hits the right ear at the peak of its amplitude and the left ear at the middle of its amplitude. Is that what you're describing, or something else? We disagreed above, but may come to agreement if I understand your stance better.

 

 

[bdiament]

Hi Egon,

 

"...And Barry- what do you mean by wavefront arrival time? Is this the phase? I'm picturing a wave, going up and down with its amplitude and frequency, and say that wave at a given frequency hits the right ear at the peak of its amplitude and the left ear at the middle of its amplitude. Is that what you're describing, or something else? We disagreed above, but may come to agreement if I understand your stance better."

 

I'm not talking about relative phase per se but the arrival time of the wavefront, i.e. the onset of the sound. In other words, not a sine wave but say, the low frequency component of a tympani strike. (In the case of subs, just the low frequency component.)

 

Hope this helps.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[Shadorne]

Harmonic distortion is the added harmonics that were not originally on the source signal. Harmonics are frequencies that are a multiple of the fundamental or actual note. Most instruments have natural harmonics anyway - so this can make it hard to recognize. Also our ears and brain do not recognize a change in the note with added harmonics - although the quality, timbre and loudness of the note will change significantly (but not the pitch).

 

THD stands for a sum of all the added harmonic distortions. It is easily measured by playing a perfect sine wave and then analyzing the speaker output for added harmonics that are not supposed to be there (just like they do for amps). In percent terms, 100% THD means there is as much sound at added harmonic frequencies as there is at the correct frequency.

 

Many fuss over this figure with their purchase of electronic components whereas it is almost always the speakers which add the most distortion. The most accurate sound from a speaker is from the tweeter and the worst quality sound, by far, is in the bass woofer.

 

I quote from Seigfried Linkwitz's website

 

"The importance of low distortion at very low frequencies can be deduced from the equal loudness contours. The threshold of hearing is around 70 dB SPL at 20 Hz. This is at the level of normal conversation. With increasing frequency the threshold drops rapidly. The loudness contours have an initial slope of 80 dB/dec, or 24 dB/oct, at low perceived volume levels (phon).

 

This means that if the 40 Hz 2nd harmonic of a 20 Hz tone is at a 24 dB lower level, then it will sound equally as loud as the fundamental. This corresponds to 6% 2nd harmonic distortion. The 3rd harmonic distortion would have to be below 1%, or over 38 dB down, in order that it is less loud than the 20 Hz fundamental. It all leads to very low distortion requirements. The fundamental frequency sound pressure level needs to be above 70 dB to even become audible and it should not be masked by higher frequency distortion products.

For a detailed investigation of requirements see: Louis D. Fielder & Eric M. Benjamin, "Subwoofer performance for accurate reproduction of music", JAES, Vol. 36, Number 6, pp. 443 (1988)."

 

Unfortunately, what Siegfried is saying is FACT. It is pure science. Worse - it tells us that the typical really good subwoofer (with say 5 to 10% THD at reasonable listening levels) is woefully inadequate.

 

You can find subwoofers that perform much better than REL or the prototypical home theatre subwoofer. There is a wealth of information on subwoofer distortion on the "HT Shack Subwoofer Tests" - most subwoofers tested performed miserably - not even close to meeting the criteria defined by Seigfried and demanded by the physics.

 

The top models from Genelec, ATC, SVS, JL are among the best subwoofers I am aware of - there are others but precious few (a good woofer costs over $1000 alone and most manufacturers will put something really cheap in their design in favor of a nice gloss finish or veneer on the box - looks sell, people are not discerning with sound - so quality does not). There are others but the kind of quality required means that inevitably there are all very very expensive - relatively more expensive than your conventional home audio two-way speaker.

 

 

 

[Egon]

Wow, that was an explanation I could understand. I'm glad I asked because it would have taken me a long time to find that information so clearly explained.

 

That seems like a reasonable explananation. Our ears can't localize low frequencies, as years of research states. However, we can localize the other noise that comes out of the average subwoofer that shouldn't be there but is.

 

This explanation lets science/physics and Barry's finding that he could localize a sub coexist happily. My simple brain likes it. As long as the sub he heard wasn't in the small few that has ultra ultra low THD, because that would just confuse me. I didn't check out your references yet to see if subs even exist that can meet this requisite ultra low THD.

 

Thanks again for the explanation, I learned something today. I'm sure THD in components before amplification (which would amplify the distortion too) matters, but maybe I won't base my buying decisions heavily on it from here out.

 

[bdiament]

Hi Egon,

 

"...Our ears can't localize low frequencies, as years of research states..."

 

The assumption that it was harmonic distortion that allows localization of the sub is, in my view, at very best, a mistaken one. (Didn't you say in an earlier post that you could not localize your own sub? Where were the harmonics then?)

 

The test I describe is specific in using a low distortion sub and driving it at a sufficiently quiet level so as not to put it in the region where harmonics come into play.

 

I would submit that if you seek it out, you'll quite likely also find "research" regarding the evolutionary purpose of localization down into the bass. (I have not sought it out.) As I've said before on many occasions, one can pick any position on any topic whatsoever and find a "paper" somewhere that will support that position.

 

In any event, this may be one of those subjects (like audible differences between CD pressings containing the same data, cables sounding different, etc. etc.) where some folks argue one thing and my direct experience repeatedly tells me something else. In circumstances like these, I can only hope folks agree to disagree.

 

All I can suggest is, one of the reasons why most subs in most systems sound so (to me) glaringly out of place, failing to blend and become part of a concerted "whole" is due to the assumption that cannot localize bass.

 

Incidentally, similar thinking is involved in the approach taken by many vinyl mastering engineers, who for reasons of "safety" and convenience, use a matrix to mono out the bass on the records they cut, sometimes below 40 Hz, other times below 140 Hz, etc..

 

Just my perspective, of course.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[Shadorne]

Barry,

 

You say

 

"The test I describe is specific in using a low distortion sub and driving it at a sufficiently quiet level so as not to put it in the region where harmonics come into play. "

 

So what sub were you using and what was the SPL level?

 

Are you aware that magnetic field hysteresis in a subwoofer voice coil design (steel parts, eddy currents) makes it impossible to eliminate 3rd order harmonics below 40 db on conventional designs. This is another fact of physics that is known since the 30's. Recent research has allowed a further reduction of another 10-15 db in 3rd harmonic distortion but I am only aware of one manufacturer using this approach.

 

I recommend you read this AES paper: A Theoretical Analysis of Eddy-Current Effects in Loudspeaker Motors*, J. R. BOWLER**, N. HARFIELD**, AND N. P. MERRICKS***, AES Member, Department of Physics, School of Physical Sciences, University of Surrey, Guildford, Surrey GU2 5XH, UK.

 

 

 

 

 

[bdiament]

Hi Shadorne,

 

I did not measure the SPL level but would guess it was in the low to mid 70s.

I've done this test with a number of different subs now. Which they were is immaterial. I understand you believe I was hearing higher harmonics that gave away the sub's location and I would hope we can agree to disagree on this.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[bdiament]

Hi Shadorne,

 

I did not measure the SPL level but would guess it was in the low to mid 70s (not at all loud).

I've done this test with a number of different subs now. Which they were is immaterial. I understand you believe I was hearing higher harmonics that gave away the sub's location and I would hope we can agree to disagree on this.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[Shadorne]

Well I guess we will have to agree to disagree. For starters, according to the science, the quality of the sub is extremely important. It needs to be an exceptional quality subwoofer in order not to be able to locate it.

 

[Gedlee]

I think that people are missing a critical point. Being able to localize a sub when there are no other sources is entirely different than localizing it with other HF source present. A solo sub is not a realistic test and the results of doing are pretty much irrelavent. Use multiple subs with mains on and you will not locaize the subs.

 

[bdiament]

Hi Gedlee,

 

The point of the test is not to localize the sub but to show that humans can localize bass.

Eliminating the mains leaves only the frequencies carried by the sub for the localization test.

 

To your point, I would differ on being able to localize a sub with a HF source present. The system in which I found the hidden sub was one incorporating a number of electrostatic speakers that were operating when I felt the bass was all coming from behind me and looked behind the panels reproducing the rear center channel.

 

Of course, in a properly set up system, none of the speakers (main or subs) will be localizable per se. The speakers should not be localizable. The images on the soundstage should be localizable.

 

Anyway, the larger point was about localizing bass frequencies (i.e. real life is stereo all the way down), not about localizing subs in a well set up system.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com