DIY "4345" Project

[pos]

The room is probably the problem with any response in the upper end. You can cross the eighteen and the ten lower. It isn't written in stone that you have to cross over at 290Hz or 340Hz. Anything that works in the 200 to 400 Hz range in your room will do.

That is quite interesting because this region (200-400) is right where the Schroeder frequency is in most roms. That is the frequency under wich modes become really sparse and individually noticeable and where Earl Geddes or Todd Welti suggest to use multiple sources to simulate those lost modes (ie multiple subs).

And whereas multiple subs are an ideal solution under 100Hz (because localisation), the upper region up to the Schroeder freqeuncy (100-200 or 100-300, depending on the size of the room) remains a problem in most cases.

Wayne Parham (PiSpeakers) suggest to use multiple sources for this range, but closer to the main speaker to avoid localisation problems.
This is what the E2 or 4435 do: two woofers playing the lowest octaves together, enlarging the radiation surface and exiting different modes of the room.

Well, that could also be done with the 4345 (if sufficiently raised from the ground to avoid problems with the 2245 in its upper range).
The 2245 and the 2122 can play together down to maybe 100Hz (and multiple subs would be used under that).

Here is a small picture explaning the proposed crossover (these are acoustic slopes, not just electrical ones).
This is something I plan to try with my 2245H/2020H, with a digital crossover.