ZilchLab said:
I'm sorry but I don't agree that the JBL horn meets my criteria at all. It is not constant directivity and it has serious resonance problems as all the data shows. The JBL horn will sound very harsh while the ESP waveguide will not. If you like harsh then you'll like the JBL.
The hole on-axis is ignored in my crossover design because it is unimportant. I don't toe-in to avoid it, I don't worry about it because I am never on axis.
soongsc said:
I think you've got that backwards. The horn has the major resonances that decay slowly. The fast decay on the waveguide is expected because of the foam plug and the change in the decay rate is probably noise in the impulse response measurement (that does appear to be a noisy impulse response if you look in the time domain). This later decay is more than 20 dB down. The decay rate has to be fairly linear in any linear system. Acoustic loading is likewise linear and its effect cannot depend on level.
augerpro said:
Quite right - this is not a waveguide. My mistake, I couldn't see this diffraction slot from the photos.
Re: Waveguide or horn?
I find it very difficult to identify HOMs myself. Gotfried Buhler in Auchen did measure them in some work that he did some years back and found that they had little effect on the polar response. But he did not consider the audibility of them. They would be much more audible than their effect on the response because they are time delayed. Our work showed that this time delayed signal effect can be quite audible even at very low levels.
This whole discussion here points out how one can see whatever they want in a set of data. One person sees one thing and another person sees something else. Thats why I say that making measurements is only half of the job, Interpretation is the other half.
It is interesting to note that theoretically a spherical wavefront inpinging on circular aperature normal to it, MUST have a hole on the axis. This is exactly the same thing as the light shadow from a disk where there is a bright spot right smack in the center of the dark side of the disk. So why don't some circular devices exhibit this phenomina when they should? Its obvious, they aren't really spherical waves at the mouth, they have been disturbed somehow and are not coherent enough to cause a hole on axis. So one COULD hypothesize that any device that doesn't have a deep hole on axis does not have spherical waves at the mouth.
There are many things that I can see in my waveguide driver combinations that I cannot see in other designs. The reason again is quite simple. As the device gets "purer" in the sense of creating a spherical wave free from diffraction and reflection things emerge that are obscured in the less coherent designs.
No one who has ever heard my waveguide fails to agree that they don't sound like horns. I can tell a horn blindfolded every time, but my waveguides are hard to detect from a good tweeter. This was shown in the blind test of some 16 people years ago. No one guessed that the Summa was a horn. The JBL 4430 was obvious.
kstrain said:
I find it very difficult to identify HOMs myself. Gotfried Buhler in Auchen did measure them in some work that he did some years back and found that they had little effect on the polar response. But he did not consider the audibility of them. They would be much more audible than their effect on the response because they are time delayed. Our work showed that this time delayed signal effect can be quite audible even at very low levels.
This whole discussion here points out how one can see whatever they want in a set of data. One person sees one thing and another person sees something else. Thats why I say that making measurements is only half of the job, Interpretation is the other half.
It is interesting to note that theoretically a spherical wavefront inpinging on circular aperature normal to it, MUST have a hole on the axis. This is exactly the same thing as the light shadow from a disk where there is a bright spot right smack in the center of the dark side of the disk. So why don't some circular devices exhibit this phenomina when they should? Its obvious, they aren't really spherical waves at the mouth, they have been disturbed somehow and are not coherent enough to cause a hole on axis. So one COULD hypothesize that any device that doesn't have a deep hole on axis does not have spherical waves at the mouth.
There are many things that I can see in my waveguide driver combinations that I cannot see in other designs. The reason again is quite simple. As the device gets "purer" in the sense of creating a spherical wave free from diffraction and reflection things emerge that are obscured in the less coherent designs.
No one who has ever heard my waveguide fails to agree that they don't sound like horns. I can tell a horn blindfolded every time, but my waveguides are hard to detect from a good tweeter. This was shown in the blind test of some 16 people years ago. No one guessed that the Summa was a horn. The JBL 4430 was obvious.
It looked to me like the impulse response for the waveguide that I posted before was pretty noisy. In fact the low level stuff at later times is not decaying at all and since there is foam in the waveguide this cannot be coming from the waveguide itself. I've never looked at a CSD for these before and not sure how well my non-anechoic gating of noise will work at very low signal levels. There could be a lot of noise.
Could someone do the CSD for this one. It should be cleaner. I didn't look at the impulses before so I didn't notice the noise level.
Could someone do the CSD for this one. It should be cleaner. I didn't look at the impulses before so I didn't notice the noise level.
Wondering how the foam phase plug contributes to the axial hole issue. I would assume it affects the directivity. Does it broaden it? I know it's there to attenuate reflections within the horn, but it stands to reason there are other effects.
Have you experimented with different foam densities? For example EV tried to attenuate and control dispersion of their dome tweeter using 2 foam rings, the inner ring being more dense.
Thanks.
Have you experimented with different foam densities? For example EV tried to attenuate and control dispersion of their dome tweeter using 2 foam rings, the inner ring being more dense.
Thanks.
Why would this one be different? Different measuring conditions? smoothed impulse?😕gedlee said:
Skywave-Rider said:
For the most part the foam is not dense enough to cause much change in the directivity, in fact I'd have to say based on several measurements that the density that I use has no effect on directivity. Then remember that it is shaped such that all portions of the wavefront see the same thickness - so it is not a lense.
I tried about 4 different densities, and three different shapes. From all this data I selected the best shape and the best density.
My first thought was to use it to augment directivity control, another degree of freedom, but I found that the desnity required to do this was to high - too much loss.
The effect of the plug on the sound kept intriguing me since it was not doing what I expeted, but it was doing something significant. Thats why I kept pursuing it until I realized the effect that it had on the HOM. Further study showed that this was a significant factor. Further study now suggests that the foam imparts a kind of randomness to the wavefront, ala the Entropy discussion in another thread. Its likely to be a combination of all of these.
soongsc said:
So you don't think that I am honest?
There are a multitude of things that determine signal to noise, like signal level, background noise, number of averages, and even the type of averaging. I don't have a fixed procedure to lower the noise floor since its never been an issue before. But at -30 dB, as in the CSD plot, it could be an issue.
What you see in the longer times cannot be signal/system based because it basically does not decay at all. It has to be something else.
audiokinesis said:
Duke,
Would it be possible to share those measurements here for all of us to see and judge for ourselves ?
Robh3606 said:
XT1086 transitions smoothly from round to vertical elliptical at the throat, and then to horizontal elliptical in the flare....
Earl,
Thanks for your response.
Referring to the directivity pattern and placement of your product, as designed, I can’t see how the toe-in works in a control room or workstation environment. In those applications computer monitors, meter bridges, and even old fashioned traditional consoles will obscure much of the energy intended to reach the opposite side wall.
Since the AI line is a pro-sound monitor product, how could this be integrated into a typical work environment as described?
And how would you implement same into a 5.1 mix room?
Thanks.
Thanks for your response.
Referring to the directivity pattern and placement of your product, as designed, I can’t see how the toe-in works in a control room or workstation environment. In those applications computer monitors, meter bridges, and even old fashioned traditional consoles will obscure much of the energy intended to reach the opposite side wall.
Since the AI line is a pro-sound monitor product, how could this be integrated into a typical work environment as described?
And how would you implement same into a 5.1 mix room?
Thanks.
FlorianO, I can understand your curiosity but I'd rather not post my measurements. I'm a manufacturer, and I'd just as soon not give out data that plays an important role in my commercial design.
My comment itself probably gave out too much, but I didn't want to see Earl's revealing data lose a verbal comparison with data that I have reason to believe is less revealing.
Duke
My comment itself probably gave out too much, but I didn't want to see Earl's revealing data lose a verbal comparison with data that I have reason to believe is less revealing.
Duke
Skywave-Rider said:
The control room is not designed to be a good listening space and no speaker will work very well with all that "stuff" in the way. But I would say that these designs will work as good as or better than almost any other monitor speaker that I know of. My Thailand partner was a recording engineer and producer in NY, Tokyo, Bangkok and more. He said that he always wanted monitors like the ESP's but couldn't find them.
Quite honestly Kenny is the expert on control room design, having made several all over the world and I would push your question to him. Write him at kenny.jackel@Ai-audio.com.
My expertise is in listening rooms and home theater. Very different environments.
tinitus said:
In virtually 90% of loudspeakers designs this is true, but it doesn't have to be if you set out to do otherwise. To wit my designs.
I appreciate you taking the time to respond.
I believe John Storyk would disagree with you.
Properly designed control rooms are superb places in which to judge sound and well, "control it."
That requires listening in a well designed space.
Yes, there are some bad ones out there for sure 🙂
Mine (well, where I work..haha) is designed by WSDG.
I would also point out that all the studio recordings we listen to have been engineered in control rooms, not living rooms or garages or concert halls, by definition (unless they've been converted....).
I am interested in new monitor technology to see if it can be used effectively in a professional environment.
Respectfully.
I believe John Storyk would disagree with you.
Properly designed control rooms are superb places in which to judge sound and well, "control it."
That requires listening in a well designed space.
Yes, there are some bad ones out there for sure 🙂
Mine (well, where I work..haha) is designed by WSDG.
I would also point out that all the studio recordings we listen to have been engineered in control rooms, not living rooms or garages or concert halls, by definition (unless they've been converted....).
I am interested in new monitor technology to see if it can be used effectively in a professional environment.
Respectfully.
gedlee said:
gedlee said:
I'm trying to elicit some discussion of the data here.
I thought, in keeping with your policy, that we weren't going to talk (or speculate, rather,) about how stuff sounds.... 😉
ZilchLab said:
Thats not actually what I said, I said that I wouldn't discuss the way it sounds because I didn't listen to it with music.
My comment comes from a lot of experience with horns, what they do, how they measure and what they sound like. The JBL horn that I measured is a classic diffraction horn with all that that entails. There is a very good reason why everyone is getting away from these devices.
I have no problem with people talking about how something sounds as long as they realize that their opinions are not facts, and that data speaks louder than opinions.
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