Dispersion, narrow, controlled, or bi?

@phusis wrote:  "I prefer a large radiation area and front firing, tall horn or horn hybrid design with a controlled, narrow and fairly uniform dispersion pattern."

Me too!  But I haven’t done anything as large as your speakers (yet), so you are getting good radiation pattern control down lower than I am.  What are the radiation patterns of your big horn and tweeter, if you don’t mind?

Phusis again:  "Why isn’t the power response of the main speakers of a primary concern here?"

Well I suppose the NET in-room power response is the primary concern, and what I was suggesting to @erik_squires was a way of CORRECTING the in-room power response by adding correctively-EQ’d speakers whose response arrived late enough that it was only contributing to the in-room reflection field.  To put it another way, the main speakers’ power response is essentially unchangeable without also changing the direct sound, so if we want to leave the direct sound unchanged but improve the in-room reflection field, adding a pair of dedicated-to-reflections speakers is one way to do that.

Phusis once more:  "Introducing a reflective sound field "actively" with additional speakers is also an additional measure to get right. Isn’t that a degree of complexity that can invite more problems than what it tries to solve?"

Yes!  That’s why I was making a few suggestions to Erik in response to him having "often wondered what the results would be of using a separate preamp/amp/speaker pair to reflect sound." 

Tying back in to the topic of this thread, "dispersion":  Reflection-field-correcting rear-firing drivers are something I’ve been doing passively, as an integral part of the loudspeaker system design, for many years. 

At the risk of over-simplifying, imo a speaker should get two things right:  The direct sound, and the reflections. 

The direct sound is the most important, but imo the reflection field matters enough that it’s worth getting right (unless the system is set up for near-field listening). 

What constitutes "reflections done right" is an area where there are differences of opinion.  Imo the reflection field should be spectrally very similar to the direct sound; it should be neither too strong nor too weak; it should begin arriving neither too soon nor too late (the latter is virtually never an issue in a home audio setting); and the arrival directions matter, particularly for the first reflections.  

(In addition, the reflection field should decay evenly across the spectrum, and should decay neither too fast nor too slow, but this is a room acoustics issue over which the loudspeaker itself has little influence.)

My preference is generally for controlled-pattern multi-directional speakers, assuming they can be set up correctly in the room.   Dipoles and bipoles, for instance, need to be far enough out into the room.

I have been commercially involved with fullrange dipoles, fullrange bipoles, dipole/cardioid hybrids, and speakers with rear-firing drivers which are not full-range bipoles.  Imo each of these formats have worthwhile advantages, but there are always tradeoffs.

Most recently I have been involved with speakers which have relatively narrow frontal radiation patterns plus highly adjustable rear-firing drivers.  The general idea is to manipulate the reflection field independent of the direct sound, with the intention of making the reflection field more correct that it could have been with front-firing drivers only.  

When both the direct sound and the reflection field are "done right" (and obviously the room gets a vote in the latter), instrumental timbre is natural-sounding; listening fatigue is minimized or eliminated; and we are more likely to get a "you are there" spatial presentation, wherein the acoustic space on the recording is perceptually dominant over the playback room’s "small room signature". 

In my opinion.

Duke

dealer/manufacturer

@erik_squires wrote:  "... I’ve often wondered what the results would be of using a separate preamp/amp/speaker pair to reflect sound would be like.   You could completely alter the volume and even use DSP to tailor the reflections. "

If  you decide to try that some day, note that (unlike your main speakers) it is the POWER RESPONSE of the dedicated-to-reflections speakers that matters most.  You could even EQ them such that their power response "zigs" where the main speaker’s off-axis response "zags". 

@erik_squires again:  "I’m really against the idea of adding more speakers in terms of floor space"

Ime the arrival time of the additional reflection energy matters more than the arrival direction, so you might try using the vertical!  Maybe you could place small dedicated-to-reflections speakers on the floor, facing up, behind the main speakers. Often there’s some unused floor space behind the main speakers anyway.

Also, I suggest that you "shield" the dedicated-to-reflections speakers so that they cannot be seen from the listening area.  Not that seeing them is bad, but they will have some radiation to their sides, and you want to block that off because otherwise it will arrive too early and will probably have a poor spectral content.  If your main speakers are floorstanders, their width may well be adequate. 

Duke