"The speed of sound is about 1,100/sec.
Roughly speaking a sound wave travels about 1ft/milli-second." - _Scotty_
Assuming that the 1100 in your quote is meant to represent feet then this would be true. The operative word there is roughly because the speed of sound is a variable depending on temperature and other environmental variables.
I'm on the road now and cannot give this thread (my response) the attention perhaps it deserves but those two equations are basically indicating the same thing. First you're using the word " sound " and then "sound wave"... they're the same thing, traveling at the same speed.
"If you can reduce this primary
reflection's amplitude sufficiently you can achieve far flatter bass frequency response
at the listening position than is normally achieved by any other stratagem that I am aware of." _Scoty_
I did previously write that you have an interesting point and there is truth behind it.
All I'm saying is it's a lot easier to put it on paper or make a post here in the form thread than to actually implement it (four subs two of which are facing the other two) for the betterment of sound. If you've achieved that , then that's terrific and kudus to you.
For the type of music that I listen to and my preferences, I personally would never use that arrangement. I'm a two channel, two speaker person (in my case this two speakers have built-in subs). Both speakers are firing in front of me.
I never cared to listen to anything recorded where sound is coming from above me, behind me , to the sides of me , or from any other place than the front of me.
And I believe that proper room treatments are essential to achieving good frequency response and that would be true regardless of however many speakers you use and where you're placing them.
The answer to the ops question though appears that we all universally agree. Get another sub for a total of two. Or, get another three subs for a total of four. The placement of those subs becomes a completely different issue, and technically outside of the scope of the ops question.
Best.
Hal