Honestly, I for one fail to see what it is exactly that you're expecting to get.
A few facts should be clear by now:
1) yes, distortion in horns CAN be audible;
2) however, distortion in horns can also be reduced - some claim to the point of not it being an issue anymore;
3) some ways to accomplish (2) have been mentioned already, i.e.: design the flare so as to avoid diffraction-generating discontinuities; make the horn out of 'dead' non-resonant materials; etc. I would also add: use the horn with a suitable high-pass filter so as not to operate it down to too low frequencies for its size.
What else are you after? I think it would be easier to contribute something useful to this thread if you asked more specific questions (rather than persist in what comes across as rather childish pouting and sulking).
Marco
Distortion in horns is always audible at a high enough level. Consideration of the intended application is critical. If the distortion is audible in the intended application or not is a matter of design.
sorry if it comes across as childish pouting i guess i'm just dismayed at the current state of the art.
compression drivers have only increased marginally in performance since their inception.
direct radiators or cone drivers on high frequency horns is perhaps one avenue to explore.
and when it comes to horn shape or curvature they all have their own sonic signatures so yes it is an exercise in finding the right one.
i probably should not expect that there is more to this than current conventional wisdom but if putting forth the question "can the audibility of distortion in horns be reduced" is sulking,once again sorry.
what is of greater consequence to horn performance the overall shape or the surface texture?
compression drivers have only increased marginally in performance since their inception.
direct radiators or cone drivers on high frequency horns is perhaps one avenue to explore.
and when it comes to horn shape or curvature they all have their own sonic signatures so yes it is an exercise in finding the right one.
i probably should not expect that there is more to this than current conventional wisdom but if putting forth the question "can the audibility of distortion in horns be reduced" is sulking,once again sorry.
what is of greater consequence to horn performance the overall shape or the surface texture?
Surface texture has little bearing on performance unless it is absorbtive, in which case it will attenuate various frequencies dependent on the horn design.
ok i guess i can dismiss my thinking.
probably obtuse thinking on my part that a highly diffractive surface can perhaps reduce overall contribution to the final output.
i envisioned a sort of "hydroplaning effect" from the surface allowing the larger pressure gradient to pass unaffected.
probably obtuse thinking on my part that a highly diffractive surface can perhaps reduce overall contribution to the final output.
i envisioned a sort of "hydroplaning effect" from the surface allowing the larger pressure gradient to pass unaffected.
There are actually plenty of things that can be done for horns.
The posters here are simply trying to get you to try some of the available technologies.
Many improvements are beyond the DIYer.
For instance the surround can be improved
the spider can be improved
the phase plug has lots of room for improvement
Diaphragm materials can be improved
Different glues would help
Magnet material matters
And so on
For the DIYer u can make the horn larger
10fc would be a good start
A mouth round over of 1/4fc would help a lot
Make the horn strong, many use concrete
Use an OS contour
Use a piece of foam as Geddes does on his systems
The crossover matters tremendously so be very careful
match the driver -horn exit angle carefully to minimize internal reflections
All of the above have been discussed on this forum
So, there is nothing really new here
But it will make quite a difference in sound quality
The posters here are simply trying to get you to try some of the available technologies.
Many improvements are beyond the DIYer.
For instance the surround can be improved
the spider can be improved
the phase plug has lots of room for improvement
Diaphragm materials can be improved
Different glues would help
Magnet material matters
And so on
For the DIYer u can make the horn larger
10fc would be a good start
A mouth round over of 1/4fc would help a lot
Make the horn strong, many use concrete
Use an OS contour
Use a piece of foam as Geddes does on his systems
The crossover matters tremendously so be very careful
match the driver -horn exit angle carefully to minimize internal reflections
All of the above have been discussed on this forum
So, there is nothing really new here
But it will make quite a difference in sound quality
Consider the diameter of the smallest frequency 'air bubble' relative to the texture size [~13,560"_sec/f/pi] and you'll realize that the texture's various dimensons must be relatively large, enough so that the horn's need to be increased by a similar [same?] amount.
It seems better to visualize it like when making a race car's surface have less drag [friction], so removing any minor/major irregularities, then treated to a low friction coating used by SoS World Record racers is the way to go, though no clue if what they do is any better for a relatively small device operating at the SoS Vs a large one trying to break it.
FWIW, I 'blueprinted' [filled 'pores', excess welding, etc.], then finished a cast alum. horn with a baked on super high gloss automotive acrylic enamel, which made it just audibly [dare I say it?] 'slicker'/smoother sounding than just a factory spray painted one, so may be worth 'going the extra mile' if what those folks use/do are an obvious improvement over a typical high quality auto finish's coefficient of friction.
GM
I would caution everyone to keep in mind that things like hydroplaning and frictional drag on a car are static effects, I.e. non-oscillating flow. Such effects do not occur in an oscillating/acoustical wave because they take time to establish. There is "friction" in an acoustic sense, but it is quite different than the "drag" in a steady-state flow sense.
I would agree that very little has changed in compression drivers, but that is not for want of trying. I worked with B&C for years trying to improve them and for the most part there wasn't much room for any improvements. That is why I say that, to me, the driver is a commodity and any good driver works as well as any other one.
What makes a huge difference is the waveguide/horn. The sound quality of these simply dominates the entire problem, and these have changed dramatically over the last 20 years or so, to the point where all the old diffraction type horns have mostly disappeared. The waveguides change with every new iteration, while the drivers just evolve to new ways of manufacturing, some new materials, etc.
What has never been experimented with (to my knowledge) in compression drivers is the compression ratio. There have been some odd different ones, but no rigorous study of the effect of the compression ratio on sound quality has ever been done. Personally, I would not expect it to be significant, but one never knows these things before hand. (Had lots of times I expected a significant effect only to find that it wasn't!!)
What makes a huge difference is the waveguide/horn. The sound quality of these simply dominates the entire problem, and these have changed dramatically over the last 20 years or so, to the point where all the old diffraction type horns have mostly disappeared. The waveguides change with every new iteration, while the drivers just evolve to new ways of manufacturing, some new materials, etc.
What has never been experimented with (to my knowledge) in compression drivers is the compression ratio. There have been some odd different ones, but no rigorous study of the effect of the compression ratio on sound quality has ever been done. Personally, I would not expect it to be significant, but one never knows these things before hand. (Had lots of times I expected a significant effect only to find that it wasn't!!)
I am betting on compression having some positive effects on some variation of distortion. In fact I think this is exactly where the "magic" fact that horn drivers sound imho vastly superior to direct radiators. Obviously diaphram motion is in play but there must be more we do not know enough about.
so using diffraction to counter diffraction is not considered worthwhile.
on the matter of compression drivers, since Weltersys mentioned it, the rear chamber in a compression driver is an area i think (at least fueled by my low ball results) that can be easily experimented with, i removed the rear cover on a 2482 and the net effect was a readily perceived plus,not as strident but lower in overall volume.
would something like a transmission line to absorb rear radiation be worthwhile?
on the diaphragm "mod" front i used an old diaphragm that had started to crack re-glued it, then had a listen to give myself a reference and subsequently coated it with a thinned latex caulking to good effect. now i need to repeat the exercise in a more controlled fashion with measured results.
would changing the compression ratio not have a correlation to reducing the high frequency limit/range? not that i fully understand phase plugs or their design but from what i understand reducing the open area in the throat chamber in an effort to channel them(high freq's that is) out to the outside is what gives rise to the compression effect?
on the matter of compression drivers, since Weltersys mentioned it, the rear chamber in a compression driver is an area i think (at least fueled by my low ball results) that can be easily experimented with, i removed the rear cover on a 2482 and the net effect was a readily perceived plus,not as strident but lower in overall volume.
would something like a transmission line to absorb rear radiation be worthwhile?
on the diaphragm "mod" front i used an old diaphragm that had started to crack re-glued it, then had a listen to give myself a reference and subsequently coated it with a thinned latex caulking to good effect. now i need to repeat the exercise in a more controlled fashion with measured results.
would changing the compression ratio not have a correlation to reducing the high frequency limit/range? not that i fully understand phase plugs or their design but from what i understand reducing the open area in the throat chamber in an effort to channel them(high freq's that is) out to the outside is what gives rise to the compression effect?
Phase plugs are necessary for diaphragms that are not flat, but a flat diaphragm would not need a phase plug (been there done that.) As I have said before the reason for the compression ratio is efficiency. Since prior to just a few years ago no one considered a horn as a viable audiophile loudspeaker, all the emphasis was on efficiency for Pro applications. I think that is still the main focus. In a home system where the efficiency is not a bottom line requirement, the compression ratio could become a less desirable facet of horn drivers.
But I caution you to do measurements first, then listening if you must. Sure changes will always sound different, but different does not mean better. If it measures better AND sounds better then you may have something, but lacking either one of those and you have to question what you are doing. To wit, we have Pete saying that all compression drivers sound better to him and Turk saying that all cone drivers sound better to him - this is not good support for either contention. Measurements are impartial.
But I caution you to do measurements first, then listening if you must. Sure changes will always sound different, but different does not mean better. If it measures better AND sounds better then you may have something, but lacking either one of those and you have to question what you are doing. To wit, we have Pete saying that all compression drivers sound better to him and Turk saying that all cone drivers sound better to him - this is not good support for either contention. Measurements are impartial.
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no don't misquote me. i like (big) horns (and i can not lie!)
and for all the years ive spent in front of them i simply long for better.
and no i'm not going to run with my self admitted "low ball" approach but if merely "mucking" with things seems positive it does warrant more investigation, no?
and for all the years ive spent in front of them i simply long for better.
and no i'm not going to run with my self admitted "low ball" approach but if merely "mucking" with things seems positive it does warrant more investigation, no?
Horns aren't my strong suit, Earl. But I remember some Lowther cabs I heard years back. About the size of a chest of drawers, which just blasted the lounge with bass on about 2 watts of Quad amp and used a puny looking 5" driver with a whizzer. 😀
If I understand the whole horn thing, they are acoustic impedance matching devices. I'm fascinated by your foam filling of horns to reduce distortion. Smoothness of transmission must be the key. Avoid abrupt discontinuities.
The mouth of the horn must be the huge problem. Below a certain frequency they must just blow smoke-rings, if you follow?
I like the geometry of all the different things you can do too. And minimal surfaces based on soap films and rings always seem to have a potential speaker design in them. Costa's surface looks quite Tom Danley in concept to me. 😎
If I understand the whole horn thing, they are acoustic impedance matching devices. I'm fascinated by your foam filling of horns to reduce distortion. Smoothness of transmission must be the key. Avoid abrupt discontinuities.
The mouth of the horn must be the huge problem. Below a certain frequency they must just blow smoke-rings, if you follow?
I like the geometry of all the different things you can do too. And minimal surfaces based on soap films and rings always seem to have a potential speaker design in them. Costa's surface looks quite Tom Danley in concept to me. 😎
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Dr Geddes
i thought that the concave shape of typical compression diaphragms was the result of trying to sum a bunch of plane wave tubes to a smaller new opening closer to the exit of the driver?(although most i've seen are annular rings summed to a new aperture)
with respect to a flat diaphragm would there not be more problems with diffraction as the center of the diaphragm is further from the walls of the horn?
i thought that the concave shape of typical compression diaphragms was the result of trying to sum a bunch of plane wave tubes to a smaller new opening closer to the exit of the driver?(although most i've seen are annular rings summed to a new aperture)
with respect to a flat diaphragm would there not be more problems with diffraction as the center of the diaphragm is further from the walls of the horn?
not to appear contentious but i think James Bullough Lansing's original target market was audiophiles. even Altec's goal was better fidelity for theater patrons, efficiency was without doubt a factor but the premise that volume trumped fidelity even in the PA market is "fidelity profiling" that shouldn't exist.
No Viable Trade-Off Then
Starting with Edison's Phonograph and not until the arrival of the transistor amplifier, loudspeaker efficiency dominated the design of sound reproduction systems, particularly those used for for public address, cinematic, and sound reinforcement applications. Simply put, if you could not hear it, it did not matter how faithful the reproduction was. As it was, a prodigious bank of tube amplifiers was still required to drive a typical system deployed in these venues. Furthermore, the relationship between efficiency and fidelity were tightly bonded by the technology available at that time. To get fidelity you had to increased efficiency. WHG
Starting with Edison's Phonograph and not until the arrival of the transistor amplifier, loudspeaker efficiency dominated the design of sound reproduction systems, particularly those used for for public address, cinematic, and sound reinforcement applications. Simply put, if you could not hear it, it did not matter how faithful the reproduction was. As it was, a prodigious bank of tube amplifiers was still required to drive a typical system deployed in these venues. Furthermore, the relationship between efficiency and fidelity were tightly bonded by the technology available at that time. To get fidelity you had to increased efficiency. WHG
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An OS waveguide needs a flat plane wave at it throat. If this exists then the waves propagate as cleanly as is possible. But if the diaphragm is not flat then there will be a lot of phase cancellation when the wavelengths get comparable to the diaphragm curvature, so some kind of phase plug is necessary to better align the wave front to flat at the throat.
If you feed a waveguide with exactly the wave front that it wants to see then this wave will propagate with minimal diffraction and cancellation. May not seem intuitive, but it is correct. Determining what that wave front shape should be can be difficult to impossible - there will always be a "best one" but that may not be "good enough".
Yes JBL was originally in the home market, but not Altec. But the horn systems from these manufacturers where not considered "audiophile" at the time. Not like Bozak, of Warfdale, etc.
If you feed a waveguide with exactly the wave front that it wants to see then this wave will propagate with minimal diffraction and cancellation. May not seem intuitive, but it is correct. Determining what that wave front shape should be can be difficult to impossible - there will always be a "best one" but that may not be "good enough".
Yes JBL was originally in the home market, but not Altec. But the horn systems from these manufacturers where not considered "audiophile" at the time. Not like Bozak, of Warfdale, etc.
System7 - those shapes - the soap bubble problem, are catenoids of revolution, just as an OS waveguide is.
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