Dispersion, narrow, controlled, or bi?

@audiokinesis wrote:

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?

The large format Constant Directivity EV HP9040 diffraction horn (as the model number implies) has a 90 and 40 degree horizontal and vertical coverage (down to about 500Hz, it seems), and the dispersion pattern of the JBL 2405 Alnico tweeter sits at 90 and 30 degrees horizontally and vertically - in both cases according to the specs linked.  

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.

I see. So these measures being corrective are a compensation for what the main speakers are typically able to, or rather incapable of doing in and by themselves. In principle however it ultimately follows - or so it could be deduced - that the power response of that produced by the main speakers alone DOES matter as a primary factor - insofar it can be uniformly achieved in a given listening space?

From your chair: is it even possible for main speakers as standalone units to get the NET in-room power response right (front firing, di- or bipole or otherwise), or is this a matter that can be at least partially alleviated with the design approach (i.e.: from the likes of horns) and through sheer physics/size as I implied earlier? 

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. 

Why isn’t this a more widely addressed field of concern from other/more speaker manufacturers?

What I meant by "actively" (i.e.: not how the speakers are configured crossover-wise) was to point to the corrective measures being done additionally with extra speakers to aid the reflective field as an actual, actively addressed area by its designer.  

@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. 

I prefer a large radiation area and front firing, tall horn or horn hybrid design with a controlled, narrow and fairly uniform dispersion pattern. Smaller and lower horn-based designs tend to be too "beamy" and upfront sounding for my taste and more easily give off themselves as speakers than a more uninhibited field of sound.

Multi directional speakers can have an advantage with a more spacious soundstage, but generally I find them too diffuse sounding - indeed almost too or even annoyingly spacious (in which case they mayn’t have been well implemented).

A front firing only, tall and large radiation area horn-based design as described above to my ears compensates immersively through the sheer size of its radiation field with a more distinct, yet still relaxed and fuller presentation - a good, a rather natural sounding compromise, I find. 

@audiokinesis wrote:

[...] note that (unlike your main speakers) it is the POWER RESPONSE of the dedicated-to-reflections speakers that matters most.

Why isn’t the power response of the main speakers of a primary concern here? 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?

I've never heard them, but the Steinway/Lyngdorf (at least some of their models) are powered dipoles with DSP.  They look quite interesting.

Thanks for the suggestions, Duke, but honestly in terms of money and time the entire idea is well beyond me right now.  I was however thinking of a number of passive speakers that have implemented smallish rear firing drivers (like a tweeter or 2-3" mid) and think perhaps in the future a wave of active speakers could do the idea more justice.   Having a smallish amp and DSP settings for the rear firing may make for very interesting customization. 

@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

I have to agree with Duke that the rear reflections matter in imaging.  We tend to focus on absorption but the rear needs a balance of absorption and diffuse reflection to really lock in that sense of presence. 

Due to my own circumstances, I'm really against the idea of adding more speakers in terms of floor space, but 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. 

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

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