The standard studio monitor placement, is it correct?

Funny I just read about this in either Sound on Sound, or a lynda video.  They said to avoid speakers on their side if you can because of the very reason you pointed out.  They said they see it in a lot of studios, but it's basically a nono.
 
 

Ha ha, new laptop...getting used to its touchpad, which seems to be calibrated for feather-light touch! Stuff's popping up all over the screen because merely placing my palm near the thing causes a click/Enter response...oh hell, I just downloaded SQLExpress twice!
 
 
 

I have a pair of Adam A-5X's with a folded X-ART tweeter which is designed for horizontal distribution.
 
I have a pair of Neumann KH 120's with conventional tweeters, but with  a flare that is also intended to widen the sweet spot horizontally.
 
There are other nearfield monitors with this kind of design feature, so these are not optimal on their side.
 
sharke, is that NS-10 yours?!?

I use Equator D5's and the tweeter is in the center or the cone (coaxial design) with the bass port below. The are small enough that I would not put them on their sides. 
My old NS-10's were designed to sit on their sides and it did make a big difference when I changed their positions. 
It really depends on your room size and environment. 
Experiment!

There is no right answer, other than perhaps "it depends".

There are, however, a number of really good starting points, and you've already heard several of them.

Every room is different, and more to the point, every pair of ears is different.

There are configurations I've seen that I expected to be horrible, and yet the engineer was able to create mixes that translated well to the world.

To be fair, there have been rooms where I just knew it was going to be awful, and it was<G>!

And to be equally fair, there have been rooms that looked right and sounded right, but I can't recall a case where things looked right and sounded bad. Does that  mean there was never room for improvement? I'll never know!

So where do you start?

1) room symmetry, left to right - this is about as close to absolute as it gets.
2) distance to the back wall - try your best to get the back wall at least 11 feet from your ears. Can't always be done, but if it can it makes a big difference
3) loudspeaker placement (part 1) - horizontal or vertical, and free space, half space, or dog-house - every loudspeaker is designed to work optimally in one or more configurations, so you need to read the manual. If you need to rotate the tweeter to lie them on their sides (or stand them up) do so. Similarly, if there is a switch that tries to equalize the low end depending on placement use it. And don't be afraid to try alternate positions, they probably won't work, but  if they do... Similarly again, don't be afraid to try monitors on their side even if the  manual says otherwise. Worst case you'll learn why the manufacturer advised against it. About the only rule I've run across that seems somewhat universal is that it is a really bad idea to doghouse near field monitors, and it is a really bad idea to place monitors with rear-firing ports against a wall. I'm sure there are others<G>.
4) loudspeaker placement (part 2) - distance to ears, distance between - start with the oft-quoted equilateral triangle and a distance that looks right. Distance is a crap shoot! Experiment. It is the only way to know that you've found the sweet spot. Start by adjusting distance, and keeping the equilateral triangle. Once  you've found a distance that sounds  good play with separation between the loudspeakers. For distance you are primarily listening for tonal balance, although it will impact the stereo image a little. For separation you are primarily listening to the stereo image, but tonal balance can change too.

Ain't this fun?

For folks building a new room I recommend taking care of loudspeaker placement before moving any equipment into the room - it is usually easier to adjust equipment locations. Not always (a 12 foot wide console is going to take up a lot of space<G>), but  usually.
 
And while listening/experimenting with loudspeaker placement use a LOT of different material, some of your own, and a bunch of your favorite albums. And if you have any well recorded 'naked' tracks listen to them too.

There  is science here, but there is also art. Unless you are designing the  monitors and the room from scratch the art part has a lot of impact. By way of example, my new Presonus S6 monitors are a lot closer than I expected. Thus far (and I'm far from finished) I haven't been able to screw up the stereo image much, but I have found the tonal balance to change more than expected as they move back and forth.

Another example - I have a pair of Urei 809s, and right now they are on stands in the room. They used to be mounted in the wall in my old place. There is no question I like them better that way, but I'm a ways off from building the next room, so here they stand (pun unavoidable?)

display monitors cause all sorts of problems - we were better off with tape decks!!!
Not only do you need to be able to see your screens, but you need to arrange the displays and the loudspeakers such that the displays don't mess up the stereo image.

My suggestion would be to start with the minimum spacing you describe, and try moving the displays closer. If that doesn't cause audible problems then you are all set. If it does (and I fear it might) then you need to start with a comfortable viewing distance for the displays, and work with loudspeaker placement from there.

Good luck!

I have read though the scenarios for speaker placement. Some of the things (distance from the speakers and stereo image listening..I've tried). Never thought about ear level in regards to bass and treble. Makes a lot of sense. This was extremely informative information. I have been struggling with final mixes. Particularly with the highs. They always seem to get lost in the final mix.  
 
Thanks
s5m