Dispersion, narrow, controlled, or bi?


I’ve been thinking a little bit about fads and trends more along the lines of basic speaker operating principles than anything else... in particular a technical discussion at DIYaudio about cardioid speakers kind of got me thinking, the most known of which are the Kinki, ahem, Kii speakers.  That got me thinking less about the moving membranes or cabinetry and much more about the radiating geometry.  

For instance: 

  • Line arrays
  • Open baffle 
    • Genesis qualified as both in some ways
  • Electrostatic
    • Which are arguably some of the most famous open baffle speakers! 
  • Horns
  • Omnidirectional (Ohm Walsh)
  • Partially di or bi polar
    • Speakers with rear radiating drivers
    • Bose 901s were direct/reflecting
    • Snell A speakers had at least a rear tweeter
  • Coaxial
    • Some are open baffle woofers with horn tweets

 

So, keeping it all to radiating patterns, what is your take?  What have you heard or own that really has done you in? 

erik_squires

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. 

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

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?

@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. 

@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.