Optimum frequency response curves in the bass range - diyAudio
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Old 25th June 2008, 08:05 PM   #1
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Default Optimum frequency response curves in the bass range

I come across this paper which I read with interest many years ago. The author Ingvar Öhman is a knowledged person but as he used to be the president (or guru?) of Ljudtekniska Sällskapet (about; The Society for Audio engineering) here in Sweden and I am a disbeliever of their IMO somewhat dogmatic approach to the subject, I often disagree with them. But comments on this paper is most well come! And I don´t discard a scientific approach to any subject.

http://www.sonicdesign.se/optimum.html

Well, here´s another one about placement of a sub/subs.

http://www.sonicdesign.se/subplace.html
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Old 25th June 2008, 09:48 PM   #2
MaVo is offline MaVo  Germany
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I dont want to flame, but those two dont seem to be scientific at all. They are full of subjective descriptions and unclear definitions. The topic of room acoustics is described in much greater detail by gedlee or the harman papers.
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Old 25th June 2008, 10:54 PM   #3
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I didn´t want to say this myself, but I´m glad you did. There is a tendency by some in the "Audio society" to lean on "objective truths" but this approach may not be without flaws. I appreciate seriously made research but the example shown above leave some doubts. Interesting enough, as there seems to be a demand for a nearly religious belief in a Messiahs that can tell you all about what is the truth and even what to use. But as we don´t hear in the same way, probably don´t perceive rhythms in the same way, have different preferences about which flaws to accept in the not perfect world there must be some space for disbelief and opposition. Maybe it´s wrong of me to point at a society in Sweden that few of you have a chance to evaluate.
But in general it is hard to prove that something is perfect or very near it. This may be a relevant and justified criticism of any one that states he or she knows nearly everything or can recommend gear as being nearly perfect or just perfect. Of course this is just an opinion, not a fact that I can prove here and now.

As for the word scientific.
The methodology can be irrelevant. Conclusions may not be based on a statistically significant number of observations.
Other explanations to a finding have to be discussed etc.

If in theory subs may best be placed in a corner; how about my preference for not doing this. While reproduction normally is dependent on room acoustics and hence the modal behavior of the room counts, it may very well be true that some people prefer some modes not to be excited to a degree. The society has also published an article about using multiple subs and placing them in a nearly random way and then not just in the corners.....
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Old 26th June 2008, 08:06 PM   #4
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As far as placement goes I'd suggest looking at:

http://www.harman.com/wp/pdf/multsubs.pdf
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Old 28th June 2008, 03:05 PM   #5
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Thanks for the link! I have positioned my two subs out of experience and simply moving them a bit and listening. The bass I have is excellent and as the listening room is a moderately large one and somewhat "difficult" in an acoustic sense I am really surprised at the result. Being a perfectionist I don´t find any reason to continue improving it. Very good amps and carefully applied damping contribute to this. It took some years to get here though.

About the paper on Optimum frequency..... . When I first read them my thoughts were that the author wanted to make an investigation with a scientific approach but he was unable to obtain the goal.

Recently I read "The Summa Cum Laude Loudspeaker" by GedLee and my reaction was much more positive with only a very few objections. Having only studied methodology in the social sciences, I´m more or less guided by my feelings when reading technically oriented writings. This can of course be a bias as one tend to agree to things that is in accordance with some sort of cognitive "map" we all posses. In a way, our ability to adapt to new findings and revise our views is the key to knowledge.
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Old 29th June 2008, 10:56 PM   #6
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I wonder what he means by 'dynamical' and 'statical'?
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Old 30th June 2008, 04:11 PM   #7
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I guess it´s about the difference between pure sine formed waves contra complex transient ones.

I recall Richard Vandersteen reported a panel of trained listeners
being able to distinguish phase shifts for the later kind but not for rather simple signals.

In this interview he talks of phase shifts.

http://www.vandersteen.com/pages/Pdffiles/rvintrvw.pdf

And here´s another opinion by Floyd E. Toole

http://www.sonicdesign.se/tooleinw.htm


My own opinion FWW is that for certain frequencies our hearing is indeed sensitive to time domain errors.

In a simplified division there are those who are following a scientific method and are careful about which conclusions can be made.

Then there are those who pretend consciously or unconsciously to have a scientific approach but they are not knowledged or honest enough.

The last group doesn´t seem to bother, There claims are pure subjective and of course this doesn´t mean they are always wrong but their "wild thinking" has to be critically assesed at least! An example;
http://www.mother-of-tone.com/mother.htm
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Old 30th June 2008, 04:45 PM   #8
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Sorry, I was unable to edit the last part of my post due to the 30 minutes rule, so here it is:

Then there are those who pretend consciously or unconsciously to have a scientific approach but they are not knowledged or honest enough.

The last group doesn´t seem to bother. Their claims are purely subjective and of course this doesn´t mean they are always wrong but their "wild thinking" has to be critically assessed at least! An example;
http://www.mother-of-tone.com/mother.htm

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Old 30th June 2008, 05:22 PM   #9
sreten is offline sreten  United Kingdom
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Hi,

http://www.sonicdesign.se/optimum.html

Whilst familiar with the above, what is actually being reported I find
somewhat obscure, it could be very clearer, and more informative.

The subwoofer article seems based on dogma rather than enquiry.

/sreten.
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