Does it mean the GXC300 also required 90cm of space behind?
The AT screen will need to be about 1.3m from the wall.
There are two ways to this,
If you have a very large space, you can place the speakers away from the boundary, 2.2m, ie 1.3+0.9m location .
They will be ideal and free from boundary interference. Boundary interference is a result of the bass frequency energy reflecting off the back wall from your speaker, and causing a cancellation with the direct sound .
Another methodology is placing the speakers as close to the wall, or flush mount it to avoid the existence of a boundary. That way there is no energy reflecting off the back wall.
The rule of thumb is the closer your speakers are placed against the wall, the higher the null frequency/ cancellation frequency/ Null is. You then have less distortion and higher output from boundary gain, getting the phase & timing correct is a lot easier
Doesn’t mean the cancellation won’t happen , it’s just that we are now shifting the cancellation frequencies to a higher frequencies so we can use effective absorption panels to handle the bass
When you do that and you now have a crossover of 100hz, sending all those energy to the subwoofers, you now possess the capability to place the subwoofers in any part of the room to handle these cancellation frequencies
When you go full range, You cannot move your main speakers. Because u need to maintain the stereo imaging and balance. But you will suffer from these room modes. Hence I would advise you not to go full range.
Since you have the same speakers, it’s a lot lot more easier… when I get home, I’ll pull out the data I have on this…
I’ll explain here, exactly why one should not go full range , but instead use the subwoofers to handle Low frequencies where you have tons of options for subs placement and acoustic treatment to bring your system to nirvana