jzagaja said:
I'm sorry, I don't quite understand. Do you mean that the phase plug have no "flare"? Well thats not only not new, its not even a good idea. The phase plug should have some flare, but what to choose? Older drivers using the concept of "cutoff and flare rate" figured that the lower these were the less it would interfer with the "horn". But on a waveguide the situation is quite another thing and this flare rate should be conceivably be as large as possible. This is the way the driver are going and it makes perfect sense.
So "A driver without a conical part" would not be a good idea IMO.
Eighteensound says pure phase plug isn't like JBL's "optimized aperture":
http://www.google.com/patents/about?id=17OUAAAAEBAJ&dq=Andrea+Manzini
http://www.google.com/patents/about?id=17OUAAAAEBAJ&dq=Andrea+Manzini
Hello Jean-Michel et all
Have a question about going the multicell road with my cylinder wave horn.
I'd like to section my dipole horn *as it is* (thus not exactly a multicell).
Reason is that I think there might be less bouncing between the horizontal planes – smoothening out the somehow ragged FR plots.
Well not exactly less bouncing but maybe less impact in FR if I add a bunch of additional horizontal planes spaced less than wavelength of top frequency.
Now it is around 15cm between the horizontal plains and I could do roughly 6mm.
For a second step – it seemed to me to be a good idea to section in the vertical plain as well – with the benefit of calming down the top end irregularity (caused by driver size interference IMO).
Usual multicell horns aren't simply sectioned horns though – so what would be the outcome if I only insert sheets of wood (no profile whatsoever) and along what lines would I have to insert that section-sheets?
Maybe you can point me to a place where this already was discussed?
Michael
Have a question about going the multicell road with my cylinder wave horn.
I'd like to section my dipole horn *as it is* (thus not exactly a multicell).
Reason is that I think there might be less bouncing between the horizontal planes – smoothening out the somehow ragged FR plots.
Well not exactly less bouncing but maybe less impact in FR if I add a bunch of additional horizontal planes spaced less than wavelength of top frequency.
Now it is around 15cm between the horizontal plains and I could do roughly 6mm.
For a second step – it seemed to me to be a good idea to section in the vertical plain as well – with the benefit of calming down the top end irregularity (caused by driver size interference IMO).
Usual multicell horns aren't simply sectioned horns though – so what would be the outcome if I only insert sheets of wood (no profile whatsoever) and along what lines would I have to insert that section-sheets?
Maybe you can point me to a place where this already was discussed?
Michael
Hello Michael,
Few rare multicell horns are simply sectionned,
as an example give a look to the Western Electric 25A
http://www.moviemice.com/we/horns/diagram-263.jpg
The first problem I see with the vertical sectionning you are studying is that, as the sections become thinner and thinner, air viscosity plays an increasing role, reducing the speed at the contact to the inserted horiziontal "blades".
Parallel blades like this acts acoustically as resistive load so you'll loose efficiency.
As you didn't publish the FR plots without equalization by Acourate, I cannot say what are the variations in the FR plots you mentionned.
If we hypothesize a quasi cylindrical wave inside the horn (at least at low frequency) , only diffraction and reflection at the mouth may destroy the pressure field inside the horn. Does the sectionning you plan to perform will cure that, I don't think. But you should do the experiment as it is the kind of method that can lead to interesting results and probably intersting discussion.
Best regards from Paris, France
Jean-Michel Le Cléac'h
Few rare multicell horns are simply sectionned,
as an example give a look to the Western Electric 25A
http://www.moviemice.com/we/horns/diagram-263.jpg
The first problem I see with the vertical sectionning you are studying is that, as the sections become thinner and thinner, air viscosity plays an increasing role, reducing the speed at the contact to the inserted horiziontal "blades".
Parallel blades like this acts acoustically as resistive load so you'll loose efficiency.
As you didn't publish the FR plots without equalization by Acourate, I cannot say what are the variations in the FR plots you mentionned.
If we hypothesize a quasi cylindrical wave inside the horn (at least at low frequency) , only diffraction and reflection at the mouth may destroy the pressure field inside the horn. Does the sectionning you plan to perform will cure that, I don't think. But you should do the experiment as it is the kind of method that can lead to interesting results and probably intersting discussion.
Best regards from Paris, France
Jean-Michel Le Cléac'h
mige0 said:
propagation of waves along surfaces AND convex (dome) or concave (conus) source
dear jean-michel lc, mr bean (not atkins) and others.
It is my opinion that in the troath of the horn, where sound is born, the ultimate core of all distortions is born also. Most of your mathematical simulations take in account a flat source: not a convex or concave surface like we use in practice. The sound coming from the center or the outer bounderies of the moving surface does have a certain delay (1 to 2 cm is significant at these frequencies) compared to each other. I think, I never have seen this take into account in your models. A further approach into reality is taking into account the propagation of sound-waves on more or less rude surfaces.
Question: Have you ever tried to reshape those horns for compensating these 'realities'?
PS: this might be the answer why multicell horns are better adapted on dome sources, because they have a more linear (flat)source for each of their horns.
dear jean-michel lc, mr bean (not atkins) and others.
It is my opinion that in the troath of the horn, where sound is born, the ultimate core of all distortions is born also. Most of your mathematical simulations take in account a flat source: not a convex or concave surface like we use in practice. The sound coming from the center or the outer bounderies of the moving surface does have a certain delay (1 to 2 cm is significant at these frequencies) compared to each other. I think, I never have seen this take into account in your models. A further approach into reality is taking into account the propagation of sound-waves on more or less rude surfaces.
Question: Have you ever tried to reshape those horns for compensating these 'realities'?
PS: this might be the answer why multicell horns are better adapted on dome sources, because they have a more linear (flat)source for each of their horns.
Re: Re: propagation of waves along surfaces AND convex (dome) or concave (conus) source
Not true: it doesn't create a true time alignement, impossible to compensate for 2cm on a distance equal order without offering a lot of quality (read distortion or efficacity). This is the place TAD (and their former JBL-engineer) knows what is the prime in making phase plugs in as many splits as possible: diffusing air-velocity into pressure-waves.
Besides: horns are used as is: mostly without taking into account wether source is concave, convex or flat.
gedlee said:
Not true: it doesn't create a true time alignement, impossible to compensate for 2cm on a distance equal order without offering a lot of quality (read distortion or efficacity). This is the place TAD (and their former JBL-engineer) knows what is the prime in making phase plugs in as many splits as possible: diffusing air-velocity into pressure-waves.
Besides: horns are used as is: mostly without taking into account wether source is concave, convex or flat.
phase plug on compression drivers
sorry, maybe I was wrong, but still I'm convinced there are some reasons why multicell-horns are adapting better to the throat-waves by slicing them deep in the horn in different sections. One of these reasons may be that the wavefront after the phase plug isn't that uniform as simulations may predict.
Is there anyone out there who tried to adapt a driver to a horn the other way ie. with the back (convex side) at the horn mouth, and the other side tuned to the desired back volume?
This way you have a direct true expansion instead of compression-expansion.
sorry, maybe I was wrong, but still I'm convinced there are some reasons why multicell-horns are adapting better to the throat-waves by slicing them deep in the horn in different sections. One of these reasons may be that the wavefront after the phase plug isn't that uniform as simulations may predict.
Is there anyone out there who tried to adapt a driver to a horn the other way ie. with the back (convex side) at the horn mouth, and the other side tuned to the desired back volume?
This way you have a direct true expansion instead of compression-expansion.
Re: phase plug on compression drivers
This guy did:
http://www.vt52.com/diy/myprojects/speakers/oris103c/oris103c.htm
He was not impressed.
lieven said:
This guy did:
http://www.vt52.com/diy/myprojects/speakers/oris103c/oris103c.htm
He was not impressed.
