Room modes & room shape

[Rip Van Woofer]

<font color='#000000'>Direct from The Man, Siegfried Linkwitz:

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&quot;Calculations of room modes, though popular, are not practical for predicting optimum speaker placement or listener position. For this one would need to calculate the transfer function between speaker and listener. The transfer function is related to the room modes, but much more difficult to determine. Never-the-less, room mode calculations are often invoked to predict &quot;optimum&quot; room dimensions. They fail to take into account any specifics about speaker placement, source directivity and source type (monopole vs. dipole) that determine which modes are excited, and in combination with the absorption properties of different room surfaces, to which degree these resonances build up. Some people think that by making the room other than rectangular or using curved surfaces, that they can eliminate standing waves. They merely change frequencies, shift their distribution and make their calculation a lot more difficult.&quot;

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In other words, kids, don't waste your time trying to calculate your room modes for speaker placement, and don't sweat it if your room is either perfectly symmetrical (for fear of standing waves) or asymmetrical. Use speaker placement in conjunction with your ears and/or measurement and electronic EQ to get the best sound from the room you have.

Oh, and all else being equal, a big room is better than a small room.

The more I learn about audio, the more I realize that KISS is still a great guiding principle! Otherwise you just drive yourself nucking futz! And you risk descending into Audio Hell.

Enjoy your music!

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[Yamahaluver]

<font color='#0000FF'>Very nicely put, after spending months of sleepless nights and raking up all my resources, all I did was move my mains away from the wall and more to a nearfield listening position and voila, perfect sound.</font>

 

[Chuck]

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Rip Van Woofer : Direct from The Man, Siegfried Linkwitz:

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&quot;Calculations of room modes, though popular, are not practical for predicting optimum speaker placement or listener position.&quot;

Rip, I hate to expose my ignorance, but in all honesty, I had no idea that anyone thought room nodes could be used to determine optimal loudspeaker placement.  Just calculating the nodes in relatively simple rooms can be daunting (try it using a hand calculator), and in the real world rooms are horribly complex.  Certainly we can draw some conclusions about some of a rooms acoustical characteristics by considering the nodes, but translating that into speaker placement is unlikely.  So much will depend on the loudspeaker itself the nodes alone can't tell us much about optimal placement.  I guess I'm glad to see that Linkwitz agrees, but I'm dumfounded that the question even came up.  

There have been studies of the way placement and modes interact, but even these use idealized rooms and unrealistic transducer assumptions.  At least that's all I've seen on the topic.  If there is more (of merit) then I'd like to know more.

It does seem reasonable, at least in theory, that if we have enough information about the room and the transducers we could model both and use automated methods to find ideal placement, but the task seems more than a little daunting.  I'd be impressed to learn that someone had sorted it all out.  Just too many darn variables.</font>

 

[Rip Van Woofer]

<font color='#000000'>I have seen room modes come up here and in other forums from time to time, but the main thing I wanted to get across is for people not to get too nuts about their rooms and room treatment. It was just an informational post to get people to stop &amp; think a bit!

More broadly speaking [rant warning!]: the more I seek out and read (within my artsy/humanities educated limitations) the work of genuine authorities on audio -- by which I mean the actual scientists and engineers who study and publish on things like E.E., acoustics, and psychoacoustics* -- the more I conclude that most of us 'philes are just trying too hard, spinning our wheels, and spending lots of money unneccesarily (but hey, ain't that What Makes America Great?). The Big Brains who design our stuff, or do the basic research behind the designs, have already done the heavy lifting for us. All we really need do is shop wisely, maintain a healthy skepticism toward marketing claims and the outre ramblings of the high-end cultists, pay some attention to speaker placement and the acoustic quality of our rooms, and then just enjoy the music. Isn't that the point, after all? Spend the money you save thereby on actual live concerts. In particular, your local symphony orchestra/chamber music ensembles/indie bands can use the money a hell of a lot more than the corporations who make our beloved gear, and give at least as big a return on investment. No knock on the quality gear mfr's intended.

*Footnote: You won't find them in the likes of Stereophool!</font>

 

[av_phile]

<font color='#000000'>Good suggestion there Rip.  Better spend the money on attending symphonic concerts.   Afterall, that's what being an audiophile is supposed to be.  Loving the music.  Often, and i am also guilty of it, we audiophiles become lovers more of our equipment than the music it's supposed to play.  So we spend oodles on them and the room they're in.

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[EdR]

<font color='#000000'>And let me add my complete agreement to the previous two posts.  

Don't forget that from most listening positions, you can't hear only the speaker.  What hits your ears is the interaction between the speaker and the room with room acoustics playing a major role in your ultimate enjoyment and the value you're getting from expensive speakers.  Thus, I would maintain that time spend educating oneself on rational room acoustics and a few dollars spent 'tweaking' them would pay back much higher dividands than tweaking cables or other things.

That said, here's my 'gold standard' for listening and judging quality which is that when I'm listening to well recorded music, that I can close my eyes and nothing will audibly indicate that I'm not in the club or concert hall.  Admitedly a very tough standard and one that can only be aspired to.  However it gives me a &lt;subjective&gt; standard of comparison.  

One of the ways I judge soundstage imaging is to close my eyes and 'look' at each instrument.  So, for example, when a drummer goes from the snare to the cymbals, if it seems to be localized in a slightly different place- I figure that's a pretty good image from the speaker.</font>

 

[av_phile]

<font color='#000000'>A colleauge of mine actually has it reversed.  While seated in the middle of the front section of a symphony concert, he would close his eyes  I asked him if that was by habit as we normally close our eyes when listening at home.  He said yes. And added, &quot; i was imagining i was in my room and the sound closely resembles my Onkyo set-up.&quot;  

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[Chuck]

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av_phile : A colleauge of mine actually has it reversed.  While seated in the middle of the front section of a symphony concert, he would close his eyes  I asked him if that was by habit as we normally close our eyes when listening at home.  He said yes. And added, &quot; i was imagining i was in my room and the sound closely resembles my Onkyo set-up.&quot;  

Whether the music is live or recorded, closing the eyes makes it easier to focus all the attention on the sound.  The down side is that once I'm totally absorbed, I tend to fall asleep.  That's OK at home but it's not polite to snore during a live concert.  

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[Chuck]

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av_phile : &quot; i was imagining i was in my room and the sound closely resembles my Onkyo set-up.&quot;  

I've been known to do that too.  

(But I have different brands of equipment.)</font>

 

[soundriven]

Room Modes Calculator Spreadsheet

I have posted a very usefull XL spreadsheet (usefull for Mac OS X users) on my website that instantly calculates and graphically displays room modes for any given rectangular room, once LWH dimensions have been entered. I am only minutes new to this wonderful web site and organization (?) so please forgive me if this sort of thing is old hat...

To download, go to www.homepage.mac.com/soundriven and look on the "Downloads" page for a file entitled "Frequency-response.xls". It's a very small file and should download quickly. It may actually work for Windoze users as well as Mac — not sure.