jneutron,
The issues we are discussing in horn design are problematic to say the least. What drives the designs are the horn cutoff frequency and the flare rate that is chosen to support that cutoff frequency. Every thing else is incidental to those two factors in most horn design. While that is the case we can of course attempt to eliminate or reduce any abrupt shape changes along the path from the initial horn throat to the final flare opening. Not creating an older radial horn lens discontinuity at the intersection of the initial throat expansion and the attached flare would be the most significant area that can be improved and that is the basis of what the oblate spheroid designs are obvious improvements in. Any waveguide is a combination of compromises as with any direct radiator. We just have to chose our compromises carefully and attempt to cause the least harm.
The issues we are discussing in horn design are problematic to say the least. What drives the designs are the horn cutoff frequency and the flare rate that is chosen to support that cutoff frequency. Every thing else is incidental to those two factors in most horn design. While that is the case we can of course attempt to eliminate or reduce any abrupt shape changes along the path from the initial horn throat to the final flare opening. Not creating an older radial horn lens discontinuity at the intersection of the initial throat expansion and the attached flare would be the most significant area that can be improved and that is the basis of what the oblate spheroid designs are obvious improvements in. Any waveguide is a combination of compromises as with any direct radiator. We just have to chose our compromises carefully and attempt to cause the least harm.
I swear! People can complicate audio design, just to hear themselves talk. Horn throat distortion is real. It can be VERY critical, although JBL and others have attempted to minimize it with better horn drivers and faster flare (for the actual working range) throats in RECENT years. I must say that JBL did NOT appreciate my input, 40 years ago on the same subject. Now you would think that they improved things, just because they could. '-)
Please don't confuse the issue, Wavebourn. That is WHY we went to line arrays, 40 years ago, and retired as many horns as we could.
I am not quite sure why you posted that. We are discussing the technical nature of distortion mechanisms in the throat and compression chamber. Do you have any input in that regard?
jn
I don't confuse. I totally understand why I use line arrays, but never horns. 😀
Well, almost. My concrete waveguide under the floor can be viewed as a short horn.
Exactly! Big surface area, tiny displacements, high sensitivity, low distortions.
Well, also tall. Like that stick with 64 capsules 12 mm each I use as an experimental tweeter in the central channel in my HT.
That's what my main agenda is ... I believe, very strongly, because I've experienced it many times, that the illusion can be maintained no matter how close one gets to the speaker drivers. It's all a matter of degree, the system has to be absolutely correctly aligned for this to happen, requires extreme fussiness about every detail, but when you get it right there's no questioning about the effect: the ear/brain is happy to be fooled into thinking that the speakers aren't in the room, no matter what. And all the adjectives that people throw around about impressive sound all make sense ...
Frank
No, still not happy ... remember I only was working with a single speaker, the stereo pairing adds 6dB in the "sweet spot", so now that 256W/channel is pumping 118 + 6 = 124dB into your skull at 1 metre. Okay, back off to listening distance used by many, 2 meteres, roughly lose 6dB, still around 118dB. And we haven't taken into account additive effects of room reflections ...
Now, I know how many systems appear to lack grunt, but IME this is all about the quality of the sound ... lack of distortion. All my experience has shown me that a nominally low powered system working correctly creates the subjective impression of high impact, dynamic reproduction.
Frank
Pretty well that. If I kick off straightaway with classical it will be all very polite and somewhat innocuous, but it will lack life, the dynamics of the real thing. The treble has to be right for the sparkle, the punch of real music to emerge, and dynamic drivers as a class all seem to suffer this to some degree, the need for conditioning the suspensions from cold. Probably one reason why panels generally hit the "right note" on casual hearing for many ...
Frank
Still, planars and line arrays in this regards are best. They genetare kind of more uniform field, so stereo image is heard on much wider area than with point source speakers. Even when stereo image gets uncertain the volume is still heard.
Probably completely irrelevant, but the ambitious JBL at the recent hifi show, with horn midrange and treble, 94dB sensitivity, just wasn't in the game -- as soon as there was real volume the thought, PA sound, popped into one's head ...
Frank
My turn to nitpick, I guess. Uncorrelated signals add 3dB, like noise. The line sources being discussed have another advantage; if they're very big (compared to a wavelength) direct sound falls off linearly.
Thanks,
Chris
My experience with planars is not particularly positive ... yes, they generally are very pleasant to listen to but they typically do weird things with the treble because of the size of the radiating area -- the microscopic sweet spot effect, not my cup of tea.
My goal is for the stereo image to be experienced everywhere in the room, that there is no such animal as a sweet spot ...
Frank
But the signals are correlated, if the piano is centre then a note struck is very close to being purely additive, from the 2 channels.
Note that all professional active monitors sold are always spec'd on using a stereo pair, such that there is 6dB gain for the typical listening position. The top Dynaudio's do 133dB at 1 meter - what!!! - yes, assuming a stereo pair, this now makes more sense ...
Frank
Then try arrays. No sweet spot at all. Dispersed sound, like it goes from beyond the speakers. The next year I will bring on BAF 3-row arrays, open baffles: open baffles and dipoles are getting popular. 😉
My arrays at home are currently in walls.
Try it for yourself with a music source. Except at very low frequencies, the precision needed for correlation is an impossible hurdle.
Thanks,
Chris
- Status
- Not open for further replies.