"20 feet" do you have any data to back this up? Your throwing numbers out there and imo you exagerate.
You are not wrong here in your remark.....
I have not calculated the exact size where controls of the timing early and late reflections will be more difficult.... And less rewarding and easy... A great hall is not a 13 feet room....
My room is 13 feet square and it is easy to use reverberation from the back for example to create a listener envelopment experience...
And easy to use reflection from the first reflection points for the better ...
And for the skeptic my sound is not unnatural at all.....I say that because the general saying to always absorb reflections in general is simplistic... We must use our ears to know what to do in a specific room....
I did that by listenings experiments...
20 feet seems to me a good approximation separating big room and small one....But i had not calculated this scientifically with the many variables involved...
In a small room using all acoustical passive and active controls is rewarding at no cost....
I read somewhere that my 13 feet room is supposed to de difficult....
I experience the opposite...
It is because people usually use only passive material treatment ( balance between reflections,diffusions,and absorbing surfaces)
I used also a grid of resonators to control not only bass nodes but all the way up and control the timing and differentiate each wavefront of each speaker differently for each ear ...This give me a 3-d filling the room if the recording make it possible...Most classic recording are good...
My results are more amazing than anything i could dream of and no upgrade is on my future...
It is why i wrote this:
« acoustic is the sleeping princess and the future queen, the gear is the 7 working dwarves»
Most people here claim the opposite...The upgrading frustration confirm to me that i am right....people dont know how to install or embed their audio system... They read specs sheet thinking that only electronic compatibility is enough...
Perhaps the gear over some amount of money play a more important role, for those who can afford 100,000 bucks system perhaps and even in this case i listened harsh unnatural sound quality coming from many costly system in youtube ... Then acoustic for me is the key.....
My 500 bucks system is enough to make me smile...
Audiophile experience is linked to basic common sense and science especially psychoacoustic...