Best Speaker Placement Rules you've used?

Hi,

I used the Cardas style method as well, following Diagramm C. Mainly because my room is 10.5 x 17 ft, exactly in the golden ratio. It worked really well, although I thought the palcement looked ridiculaous at first.

Furthermore, here is a great free link to Ultimate AV website (Don't run away because of the V in the titel), which offers an Excel spreadsheat to calculate room modes. The sheat further calculates the frequency peaks and nulls at your listening position.

Excel calculation

All you need to do is enter your room dimensions and seating position and you get all the data you need. Nice way to play around with the seating position.

The programm also works for speaker placement since you want to avoid the speaker to sit a null point or maxima.

The interesting thing is: I took some measurements of my system/room a while ago using a corrected Radio Shack SPL meter, and I could see all the predicted "nulls" as little dips in the measured spectrum.

This is a really nice way of playing around and given my measurements it seems to work.

AND MOST IMPORTANT: Besides all this theory, don't forget to listen, your ears will tell you the best location. But the calculations might be a good starting point.

Enjoy!

Rene

Hi Hifi, sorry for the little information I provided earlier:

The spreadsheet calculates the room modes (=standing waves) for a rectangular (cuboid) listening room. It can tell you, whether there are "nulls" or "peaks" at your seating position or at the position where you place a speaker.

nulls = locations of no intensity at your seating position

peak = location of maximum intensity at your seating position

In order to calculate the "nulls" and "peaks" just enter your room dimensions and seating position in inches for the blue marked numbers on the right side/top area. In my case that results in peaks at the following frequencies:

Single peaks: 97.2Hz, 107.5Hz, 194.5Hz, 215.0Hz, and 291.7Hz.

Nulls: 53.8Hz, 161.3Hz, 268.8Hz

This means at my seating position I expect to see dips in the frequency spectrum at around 54, 161, and 269 Hz. Analogously for the peaks. You want to find a seating position in your room that gives you the least nulls and peaks. E.g. if I move my seat 6 inches back I have an additional null at 129.6 Hz that I can avoid by sitting just that little bit closer.

What is true for your seating position is true for the loudspeaker. If the speaker sits at an intensity peak position it will excite that particular room mode more efficiently, resulting in a strong increase in the sound intensity for that frequency. Thus one needs to avoid to place the speaker at that position.

As with respect to the SPL/radio shack meter measurement. A while ago I did a measurement of the frequency response of my system in my room measured at the seating position. I measured very sharp frequency minima around all the three frequencies 54, 161, and 269 Hz. These minima were up to 8 dB lower in intensity than the mean of the spectrum (actually 20dB for the 50 Hz dip).

The SPL meter measurement seems to be a good proof that these calculated nulls can easily be measured and probably be heard in form of some coloration.

How does this help you? Well, if you don't have a SPL meter and either a Rives audio CD of Stereophile test CD around to measure the frequency spectrum in your room, the spreadsheet might give you some hint which seating positions (or loudspeaker positions) to avoid without doing a measurement. I was quite amazed at the correspondence between calculation and measurement. I actually did the measurement before knowing the sheet and could not get rid of or explain the dips in the spectrum.

Also one more important comment: While you can balance maxima to some point can be treated via a room treatment (absorber) for that frequency, it is more difficult to get rid of the nulls. One solution would be to sit off center in the room (not a good idea in my opinion since you don’t want asymmetric speaker placement because of soundstaging). However, a big shelf filled with LP’s on the wall to the side of your seating position might break the symmetry and shift the null of the room mode)

In case you have any problems with the spreadsheet, please feel free to drop me an email.

Disclaimer: I am by no means a professional in room acoustics and treatment.

I hope this helps more than my initial post.

Good luck,

Rene