Five feet from the front wall

desper,

for box speakers. For bipolars I have no idea as the back wave is out of phase. I will have to think about the math on it. 
 

Macg19,

good to hear it worked out. those distances are based on wave lengths and the speed of sound. What ever the distance is from the wall times 4 it will cancel at that frequency. So 5’ is 1/4th of 20’ and that works out to 57hz (57hz has a 20’ wave peak to peak) right at where kick drums get their weight. Keep in mind it is the center point of the bass so if you have rear ports that center point is the sum of the port and driver… at least at the port tuning point. 
 

I use active crossovers so my speakers are highpassed so it it a bit more complicated as both sub and speaker distances matters. Those pictures of my system the speaker is 43” from the speaker face and 24” for the subs when using an 80hz crossover. I am using a 60hz now and have them out 4.8’ to accommodate that (I should update picture I guess). 
 

the room clutter might hurt a bit. The screen between my speakers is “acoustically transparent” screen from Screen Innovations. It is said to drop 6db starting at 2khz though audioholics measured it at closer to 10db. Regardless I have A/Bed it up and down and it is really hard to tell a difference. The JBLs are very directional at 2k so it might be moot. My real issue is the low ceiling which causes problems at 40hz. I turned my whole ceiling into a bass trap (cost $3k and about a month of work), I also have 9 bass traps in the room. It helped but still not great without room correction which I try to avoid these days. I am +/- 6db now… sounds ok. 

Genelec explains it better than I ever could.  
 

https://www.genelec.com/monitor-placement

At least for my Apogee ribbon dipoles the sweet spot seems to be 4’ off the back wall, but always experiment with your speakers in the listening space. There are too many unique factors in any listening space.

@dsper 

When I measure, it’s from the front of the speakers to the front wall and when I do toe in, it’s in relation to the front wall as well. So I have two systems. The first has the front of the speakers four feet from the wall and no toe in and the other has the speakers 42” from the front walls and about 10° toe in.

All the best.

The distance from the front wall is going to effect the mid and upper bass/lower midrange. If the face of the woofer is three feet from the front wall, the distance to the wall and back is 6 feet, that is the wavelength of about 185 Hz. Thus 185 Hz and the frequencies around it are going to be reinforced. As you move the speaker closer to the front wall the reinforced frequency increases, as you move away the reinforced frequency decreases. At five feet it is about 100 Hz. Other frequencies are attenuated. None of this is good. Sound absorption on the front and side walls is very important but it is only effective above 200 Hz at best. If you could set up the speakers 10 feet from the front wall you could reinforce 55 Hx. 28 feet would reinforce 20 Hz. All this is impossible in residential situations. 

All the above is the reason that digital room control is so important particularly in the bass.

Any other changes in sounds quality with speaker positioning depend on the timing of reflections which depends entirely on the room. These reflections effect fine detail and imaging. If reflected sound can travel 100 feet before reaching your ear you hear an echo. Thus the more sound absorption you use anywhere in a room the more you are going to decrease the likelihood you will hear an echo, which IMHO is a good thing as the echo was not in the recording. Some people actually like echoes as they add a false sense of spaciousness. All the echoes of the venue where the recording occurred are on the record. Studio recordings frequently have echo added to them to create dimension. Live recordings generally do not need it.    

Sorry for preaching.