Best Speaker Placement Rules you've used?

On Audiogon - dammed if I know. He used to have a site on Audiogon, but I can't find it now.

HOWEVER!!!!!! Go to Audio Asylum - Rives is listed as a sponsor where he has all his products and a forum. Down load his Cara program - this should do it for you.

How about a step by step process for interpreting what the spreadsheet is telling us, how you use it with the Radio Shack SPL meter, and how you go about using the data to change your speaker placements and room treatments?

- tell us more about nulls and how the SPL meter predicts them, among othe things; Thx

- I read the link, but I still don't get it fully

Thanks!

Thanks Newbee,I will check out AA. Larry

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

If you check my system and threads, you will see I have a bias for Magneplanars, but it seems I always end up incorporating the following:

1) unless specifically designed to be somewhere else, put your speakers as far out from the rear wall as possible

2) same for side walls given their associated reflections

3) moving your listening chair closer to the wall behind the chair will accentuate bass, usually with pleasant results

4) toe in is overrated --- more magical imaging and that wonderful "where is the sound coming from?!" effect comes from orienting the front of the speakers in a perfectly straight line

(Having said that, for some reason toe in seems to work better with many mini monitors placed far apart.)

5) the importance of the critical basic triangle cannot be overstated. Inches -- perhaps even centimeters -- count. Even if your speakers don't beam like Quads, they will still have a "sweet spot" when set up well.

(My audio mentor used to take 4 equal length pieces of string, attach them to the top corners of the speakers and then stretch them to the opening of his EARS to make sure both speakers were in perfect alignment.)

6) Further to imaging and toe in, speakers should be as far apart as possible, although in my experience this is rarely more than about 8 feet before the center fill collapses.

Even when the center does fill in nicely, I find > than about 8 feet gives a more vague and bloated "image".

Good question. Good luck.