Constant Directivity Cornerhorns

[Wayne Parham]

There is a lot of interest in high-fidelity constant-directivity loudspeakers these days. I'm very happy about that because I think it's the right path for making the most satisfying home sound system. I've been building my hifi loudspeakers this way for over 30 years.

I wanted to "put a bug in the ear" of others of you that are as interested in this approach as I am. Don't stop at a matched-directivity two-way or a dipole. If you have a chance, also try a constant directivity cornerhorn. I've heard great dipole speakers and I've heard great horn/waveguide speakers but I must say that nothing even comes close to a set of constant directivity cornerhorns. The improvement is that stark.

• High-Fidelity Uniform-Directivity Loudspeakers

The whole idea is pretty simple. The woofer is close enough to the walls that they don't cause any self-interference. If they're closer than 1/4λ, there isn't a reflection. It's more like a ground plane, all three surfaces the floor and both adjacent walls being acoustically close to the source. So the source radiates into eighth-space and you don't have any trouble with early or late side or rear reflections - there aren't any. The sound traveling along the walls arrives at the same time as the direct sound without reflection. The only reflections come from opposing walls.

Naturally, the midrange and tweeter cannot be this close to the walls. The acoustic scale makes it impractical at higher frequencies. So I think it is best the midrange and treble sources be horn/waveguides that provide constant 90° radiating angle to match the room corner wall angle. The midhorn needs to be large enough to provide pattern control, and it can be snuggled close enough into the corner that the walls can act as extensions at the low end. Up high, it needs to provide pattern control to keep the coverage angle within the walls. Same with the tweeter.

The thing with waveguide loudspeakers that pair a direct radiating midwoofer with a constant directivity horn is they usually only provides constant directivity in the top decade, about 1/3rd of the audio band. This is the most important region to provide constant directivity, in my opinion, because it's where all the detail is. But the next decade below that is where all the body of the music is, the vocals, instrument fundamentals, most everything, actually. This is where the constant directivity cornerhorn rules.

Not every room has the right corners to be able to take advantage of this setup. So not everyone can use constant directivity cornerhorns. But if you have the right corners, nothing beats this setup, in my opinion. A properly designed constant directivity cornerhorn system provides constant directivity all the way down to the Schroeder frequency, where multiple subs can be used to provide uniform room response. You can actually achive constant coverage of the entire audio band throughout the room this way.

[Flaesh]

thanx again!

[c2cthomas]

I showed 'em to SWMBO and asked "Honey - what do you think of these?" Her comment - "aren't those a little big for us" (meaning her).

I will need to devise a method of making them look acceptable - How well do you think they would work as a base for some potted plants etc.?

[c2cthomas]

Welllllll - I explained to SWMBO that there ARE two speakers - a pair - to a set, and she said "oh - well in that case they look very nice. They sort of remind me of Klipsh speakers (her father had a set of those)"
Soooooooooo - maybe I can start to do a bit of planning with these.

Can I find anyone out there that is willing to just put me outta my misery and get it over with???

[TerryO]

Originally Posted by c2cthomas

~~~~~~~~~~~~~~~~~~~~~~~Snip~~~~~~~~~~~~~~
Can I find anyone out there that is willing to just put me outta my misery and get it over with???

I would never ask a question like that, as my computer's inbox would be jammed packed in no time!


I started with Corner Horns and wish I still had them.

Best Regards,
Terry

[c2cthomas]

Originally Posted by TerryO

I would never ask a question like that, as my computer's inbox would be jammed packed in no time!


Best Regards,
Terry

Well it is the weekend and things slow down a lot around here when people aren't visiting the forums while they are at work - so not to worrry.

[el`Ol]

I recently experimented with this construction (three 90° circle segments assembled to a cube-shaped corner enclosure). Unfortunately it wasn't very useful in a sitting position, but standing in the narrow bass beam gave an experience I don't know from other enclosure types.

[gainphile]

Interesting. Better than dipoles hey...

So the walls effectively become mid-low horn. Would placing a normal cd speakers like econowave in the corners satisfy the requirements?

[speaker dave]

Originally Posted by Wayne Parham

I wanted to "put a bug in the ear" of others of you that are as interested in this approach as I am. Don't stop at a matched-directivity two-way or a dipole. If you have a chance, also try a constant directivity cornerhorn. I've heard great dipole speakers and I've heard great horn/waveguide speakers but I must say that nothing even comes close to a set of constant directivity cornerhorns. The improvement is that stark.

• High-Fidelity Uniform-Directivity Loudspeakers

You've nicked my diagram (page 13)

I think you are right to point out that most Constant Directivity systems are really only CD from 500 or 1000 cycles up. These days there are also a lot of "low HOM" designs that have smooth directivity but aren't really CD.

Placing a sytem tightly into the corner can remove all adjacent boundary or Allison type effects but room standing wave effects remain. You have to ask whether that placement is optimum, and optimum has to be viewed in terms of LF response at the listeners position.

Another aspect that I'll have to think about is, if you place a CD system in a 3 plane corner that roughly matches its directivity, have you lost the benefit of constant directivity? It seems any system with wide and uncontrolled directivity placed into that corner would have the same directivity. Does the system become "omnidirectional" in 1/8th space?

David S.

[el`Ol]

Originally Posted by gainphile

Would placing a normal cd speakers like econowave in the corners satisfy the requirements?

When one simulates a corner in Hornresp (not just using the eighth-space option, but simulating the corner as a conical horn one gets corner-loading up to about 1000 Hz with a 5"er in direct contact with the wall.