LOL! OK. I've been following your sims and they made me curious about what best to do behind the horn.
If the horn rolls over all the way, is that enough?
If the horn mouuth blends into a flat baffle, is that enough?
(how should it blend?)
All of that is going to sound different. What is a good approach?
If the horn rolls over all the way, is that enough?
If the horn mouuth blends into a flat baffle, is that enough?
(how should it blend?)
All of that is going to sound different. What is a good approach?
I think most people will probably not hear the difference due to listening environment or personal perception.
If the horn were build into a wall, it probably makes sense to blend with the baffle. I think it makes sense to guide the wave so that back/sides will have contiguouse rolloff like the off-axis does to the extent practical. The exact shape probably would not make too much difference, but I really don't have enough data to be certain. Wanted to do more sims, but the time it takes to do it is really too long. The computer just get messed up after 3 days non-stop sim.
If the horn were build into a wall, it probably makes sense to blend with the baffle. I think it makes sense to guide the wave so that back/sides will have contiguouse rolloff like the off-axis does to the extent practical. The exact shape probably would not make too much difference, but I really don't have enough data to be certain. Wanted to do more sims, but the time it takes to do it is really too long. The computer just get messed up after 3 days non-stop sim.
bear and paro
i've been meaning to *hear* the differences in different lip profiles/curvatures too
you can see a bit of simulation in the hornresp software but i don't think that's entirely too accurate since i dont think the software factors in the linearity of the frequency response of the compression/dome/cone driver being simulated
i think our best bet here is to go with what Jean-Michel suggests and hope for the best (the reason i'm saying this is because personally...i do not have the luxury to make a few different sets of horns to play around with)
i've been meaning to *hear* the differences in different lip profiles/curvatures too
you can see a bit of simulation in the hornresp software but i don't think that's entirely too accurate since i dont think the software factors in the linearity of the frequency response of the compression/dome/cone driver being simulated
i think our best bet here is to go with what Jean-Michel suggests and hope for the best (the reason i'm saying this is because personally...i do not have the luxury to make a few different sets of horns to play around with)
Hello Bear,
From what you wrote I can see that there something that probably I didn't clearly explained.
In fact the Le Cléac'h horn doesn't possess any lips! I mean there is no lips "added" to the mouth as it is necessary to do in a waveguide or a conical horn in order to reduce diffraction at mouth.
What you and other call lips are in the case of the Le CLéac'h horn is purely the result of the natural combination of:
1) the expansion law of the area of the wavefronts (e.g.: hypex, exponential)
2) the necessary parallelism (= equistance) of the curved wavefronts (defined as equiphase surfaces).
When calculating a Le Cléac'h horn, there is nothing special in my spreadsheets or software related to the curvature of the mouth. The curved back mouth is not intended nor provoked, it is the result of the "design by nature" of the horn.
Now on the point of baffling against rolled back mouth. If we stop the profile of a Le Cléac'h horn when the opening angle becomes 180 degrees and if from this point we decide to add an infinite baffle, we introduce a perturbation of the expansion law. This perturbation induces a partial reflection of the wave energy back in the horn and have effects on the acoustic impedance curve, and therefore on both the response curve and the group delay curve and on the pulse response (waterfall, CSD...). Those effects will be more efficient in the low frequency range of the response of the horn.
That's why I prefer to use unbaffled Le Cléac'h horns the mouth of which open at 360° minimum (Hornresp allows a max profile tangential angle of 180° so an opening angle of 360°).
You may see in attached file a theorical graph of the wavefronts I calculated. Elsewhere in the thread you can compare to the simulated pressure field at low frequency.
Best regards from Paris, France
Jean-Michel Le Cléac'h
From what you wrote I can see that there something that probably I didn't clearly explained.
In fact the Le Cléac'h horn doesn't possess any lips! I mean there is no lips "added" to the mouth as it is necessary to do in a waveguide or a conical horn in order to reduce diffraction at mouth.
What you and other call lips are in the case of the Le CLéac'h horn is purely the result of the natural combination of:
1) the expansion law of the area of the wavefronts (e.g.: hypex, exponential)
2) the necessary parallelism (= equistance) of the curved wavefronts (defined as equiphase surfaces).
When calculating a Le Cléac'h horn, there is nothing special in my spreadsheets or software related to the curvature of the mouth. The curved back mouth is not intended nor provoked, it is the result of the "design by nature" of the horn.
Now on the point of baffling against rolled back mouth. If we stop the profile of a Le Cléac'h horn when the opening angle becomes 180 degrees and if from this point we decide to add an infinite baffle, we introduce a perturbation of the expansion law. This perturbation induces a partial reflection of the wave energy back in the horn and have effects on the acoustic impedance curve, and therefore on both the response curve and the group delay curve and on the pulse response (waterfall, CSD...). Those effects will be more efficient in the low frequency range of the response of the horn.
That's why I prefer to use unbaffled Le Cléac'h horns the mouth of which open at 360° minimum (Hornresp allows a max profile tangential angle of 180° so an opening angle of 360°).
You may see in attached file a theorical graph of the wavefronts I calculated. Elsewhere in the thread you can compare to the simulated pressure field at low frequency.
Best regards from Paris, France
Jean-Michel Le Cléac'h
bear said:
Attachments
Hello Panomaniac
You wrote:
It's easy to see that the big, round horn beams more than the more complex JBL & Beyma.
I've noticed that very "pure form" horns tend to beam badly.
In the past the increase of directivity with the frequecny rise was not a problem...
Beaming became a topic of discussion between audiophiles quite recently. I am not alone to think that there was marketing issues behind that. Many audiophiles have been foolished by such claims as control of the directivity being the most important parameter for good reproducing of music. IMHO (but my opinion is what it is...) the claim of the necessity of having the same spectral balance for the reverberated field and the direct field is pure marketing and doesn't fit with my own experience (and my own experience is the country where I want to live)
Also because the Le Cléac'h horn delivers a very flat frequency response on axis, many audiophiles inclined to use a single Le Cléac'h horn to cover both the medium and the high frequency ranges. But if you need a larger "sweet spot" in the high frequency range when listening to music then the solution is simple: add a tweeter.
Lynn Olson found an argument I am very jaelous to have not found myself before as I am totally in accordance with (as it fits perfectly with my experience). The Quad ESL57 which is still one of the most musical reproducer possess a pretty high directivity (which one increases when frequency rises). But, when we listen to a pair of ESL57 in a normal room we don't feel anything wrong with a theorical tonal disequilibrium between the reverberated field and the direct field.
Please read Lynn's excellent post:
http://www.diyaudio.com/forums/showthread.php?postid=1787639#post1787639
Best regards from Paris, France
Jean-Michel Le Cléac'h
You wrote:
It's easy to see that the big, round horn beams more than the more complex JBL & Beyma.
I've noticed that very "pure form" horns tend to beam badly.
In the past the increase of directivity with the frequecny rise was not a problem...
Beaming became a topic of discussion between audiophiles quite recently. I am not alone to think that there was marketing issues behind that. Many audiophiles have been foolished by such claims as control of the directivity being the most important parameter for good reproducing of music. IMHO (but my opinion is what it is...) the claim of the necessity of having the same spectral balance for the reverberated field and the direct field is pure marketing and doesn't fit with my own experience (and my own experience is the country where I want to live)
Also because the Le Cléac'h horn delivers a very flat frequency response on axis, many audiophiles inclined to use a single Le Cléac'h horn to cover both the medium and the high frequency ranges. But if you need a larger "sweet spot" in the high frequency range when listening to music then the solution is simple: add a tweeter.
Lynn Olson found an argument I am very jaelous to have not found myself before as I am totally in accordance with (as it fits perfectly with my experience). The Quad ESL57 which is still one of the most musical reproducer possess a pretty high directivity (which one increases when frequency rises). But, when we listen to a pair of ESL57 in a normal room we don't feel anything wrong with a theorical tonal disequilibrium between the reverberated field and the direct field.
Please read Lynn's excellent post:
http://www.diyaudio.com/forums/showthread.php?postid=1787639#post1787639
Best regards from Paris, France
Jean-Michel Le Cléac'h
Jmmlc said:
Starting with the last first.
It appears from the diagram that the mouth terminates in a spiral, effectively going more than 360 degrees around.
I was inquiring IF when measured that there could possibly be a reflection back into the horn or out to the world from the edge or termination of the mouth that is 180 degrees or greater?? It would intuitively appear that such energy has already "turned" and is heading away, never to be reflected or diffracted in a direction that would effect the wavefront again??
You are saying that the effects are more pronounced as the wavelength increases WRT the dimension of the mouth's curvature?
You seemed to show a curve of another horn design that was similar in expansion (earlier post) but apparently had a very large mouth curvature to the rear of the horn. What is your opinion of this sort of approach?
Personally I am not terribly concerned about the "beaming" aspect for my room (longer than wide) where it is a benefit not to have significant HF energy sent wide or high.
My interest is in terms of a "coherent" subjective sound, where the apparent source of all energy is from the same point - yielding a properly presented stereo image.
The idea of a broader HF - or the idea of the HF being essentially of equal spread vs. frequency has some merit in my mind, but may or may not be desireable or beneficial depending on other factors in the way it actually works and sounds. I don't know if that works in the real world or not (not yet anyhow).
Btw, the term "CD" is an oxymoron to me: Contant Dispersion or Constant Directivity? Bad terminology, imho. Same stupid abbreviation two different things. Drives me nuts!!
Fwiw, horns like the Mantaray (Altec's version) fail in the nearfield because the acoustic take off point for the wave varies in distance along the length of the horn with frequency - and it is very very apparent. Sounds just plain bad. The diffraction throat is a problem as well - although one would think that converting the wave front to the equivalent of a "ribbon" shape would actually be a benefit, it seems not.
Another question, J-M, it seems that you have recommended using your expansion starting at or above an octave up from the mouth freq? What does the "native" response (no xover) look like from the horn run wide open? Is there a problem running closer to the low freq cutoff?
Put this another way, if I want to run down to 250-300Hz (assume the driver will go there), do I need to design to <125-150Hz in order to make that happen?
Regards,
_-_-bear
hi Jean Michel
i guess you've overseen my last post, nr.113.
what i'm most like to know, i've asked there :
i am curious to know your listening impressions of the setup, you will be listening this weekend.
( with big LeCleac'h horn and Radian 950pb driver )
I've used in the past a tractrix horn with 23" , and a BMS 4592nd driver, covering from 300hz, all the way up. What most disturbed me, was beaming in the treble, and some sort of sound , which bothered me, which might be HOM's, but i'm not shure about this.
With the actual configuration, LeCleac'h/S2, i observe a much improved 3D imaging. And with the separate horn tweeter and wider dispertion, sound opens up - no complains anymore....
I had last weekend a friend of mine here, which uses to listen live classical concerts, and he brought a classic cd with orchestral music, he listens live. He was impressed how close my system sounded , compared to the live event.
Angelo
i guess you've overseen my last post, nr.113.
what i'm most like to know, i've asked there :
i am curious to know your listening impressions of the setup, you will be listening this weekend.
( with big LeCleac'h horn and Radian 950pb driver )
I've used in the past a tractrix horn with 23" , and a BMS 4592nd driver, covering from 300hz, all the way up. What most disturbed me, was beaming in the treble, and some sort of sound , which bothered me, which might be HOM's, but i'm not shure about this.
With the actual configuration, LeCleac'h/S2, i observe a much improved 3D imaging. And with the separate horn tweeter and wider dispertion, sound opens up - no complains anymore....
I had last weekend a friend of mine here, which uses to listen live classical concerts, and he brought a classic cd with orchestral music, he listens live. He was impressed how close my system sounded , compared to the live event.
Angelo
Regarding the merits of free-air mounting versus cabinet or wall mounted, my purely subjective experience is that free-air sounds better, despite what theory and/or measurements may indicate.
The simple expedient of moving the horn mouth a minimum of 4 to 6 inches away from any adjacent surface makes the sound less colored, more spacious, and less tied the physical presence of the horn. When the horn mouth is resting on the top or front of the LF cabinet, the sound is more closed-in, and the images seem more like they're coming directly from the horn instead of the space around the horn.
I tried this with the eXemplars at John Tucker's house, and with other horns, using nothing more than a stack of books to lift the compression driver & horn assembly away from the bass cabinet - and the critical distance of a few inches of separation made all the difference in spatial quality. This is a quick experiment, and the results are quite obvious with well-recorded stereo.
I think JMMLC will probably concur on this point. I can't speak for constant-directivity horns such as conicals, smoothed-out conicals like the Quadratic Throat, or the Geddes OS. These seem to behave differently, and might be at their best mounted on the front surface of a cabinet - or not, since Bill Woods likes to mount his conicals in free air.
The simple expedient of moving the horn mouth a minimum of 4 to 6 inches away from any adjacent surface makes the sound less colored, more spacious, and less tied the physical presence of the horn. When the horn mouth is resting on the top or front of the LF cabinet, the sound is more closed-in, and the images seem more like they're coming directly from the horn instead of the space around the horn.
I tried this with the eXemplars at John Tucker's house, and with other horns, using nothing more than a stack of books to lift the compression driver & horn assembly away from the bass cabinet - and the critical distance of a few inches of separation made all the difference in spatial quality. This is a quick experiment, and the results are quite obvious with well-recorded stereo.
I think JMMLC will probably concur on this point. I can't speak for constant-directivity horns such as conicals, smoothed-out conicals like the Quadratic Throat, or the Geddes OS. These seem to behave differently, and might be at their best mounted on the front surface of a cabinet - or not, since Bill Woods likes to mount his conicals in free air.
Hello Soongsc,
You are right, adding lips to the mouth of a waveguide will make the first derivative of the tangential angle versus the curvilinear distance to the troat rises at the mouth.
The result will be for the waveguide a first derivative curve (of the angle) with both large absolute value both at the throat and at the mouth...
(please note: the tangential angle to the wall of a horn or a waveguide as resulting from an arctangent is equivalent of the first derivative of the profile. This means that the first derivative of the angle may be considered as the equivalent of the second derivative of the profile).
Best regards from Paris, France
Jean-Michel Le Cléac'h
You are right, adding lips to the mouth of a waveguide will make the first derivative of the tangential angle versus the curvilinear distance to the troat rises at the mouth.
The result will be for the waveguide a first derivative curve (of the angle) with both large absolute value both at the throat and at the mouth...
(please note: the tangential angle to the wall of a horn or a waveguide as resulting from an arctangent is equivalent of the first derivative of the profile. This means that the first derivative of the angle may be considered as the equivalent of the second derivative of the profile).
Best regards from Paris, France
Jean-Michel Le Cléac'h
soongsc said:
Hello Angelo,
I only attended to the listening session organized by the association Mélaudia on Sunday afternoon.
The public seems to have appreciated the large Le Cléac'h horns with their square mouth. We finished to crossover them at 18dB/octave at 316Hz (high-pass) and 4190Hz (low-pass)(both using Butterworth cells, applying my alignement/crossover method but without much measurement capability).
It was one of those rare days at Mélaudia during which people listened to music in silent (without much discussions). A proof that the music was not injuried by the system.
I am generally more critical in my comment that most people at Mélaudia and I found that the 3 ways system was very homogeneous but suffers from a bad set up.
One thing that puzzled me was the lack of progressive adaptation between the round throat of the Radian 950 compression driver and the square throat of the horn. This is a main source of diffraction at the throat and I think that some dirt things I could hear above 2kHz were probably due to this bad adaptation at throat. I found alos that the low mid lacked some presence in the beginning of the afternoon when a 6dB crossover was used and then when we turn the crossover to 18dB/octave the presence was better. A part of the partial lack of presence is IMHO due to the bad time alignment and therefore the bad pulse repsone of the overall system ( I noticed this on the note attack of the piano).
Also I think that the amplifiers were too much different one from the others and it was not the perfect match. The amplifiers were brought by different members of the association and never before they were used together. I did'nt like nor the class D amplifier used in the bass nor the SE KT 88 used for the high frequency range.
An interesting remark is that nobody complain about a too narrow directivity in the mid high frequencies (more than 20 persons were sitting in the listening room at 4 to 8 meters from the loudspeakers).
If you can have access to the following page, there is more discussion in French about that weekend at Mélaudia forum:
More http://forums.melaudia.net/showthread.php?tid=622
Best regards from Paris, France
Jean-Michel Le Cléac'h
I only attended to the listening session organized by the association Mélaudia on Sunday afternoon.
The public seems to have appreciated the large Le Cléac'h horns with their square mouth. We finished to crossover them at 18dB/octave at 316Hz (high-pass) and 4190Hz (low-pass)(both using Butterworth cells, applying my alignement/crossover method but without much measurement capability).
It was one of those rare days at Mélaudia during which people listened to music in silent (without much discussions). A proof that the music was not injuried by the system.
I am generally more critical in my comment that most people at Mélaudia and I found that the 3 ways system was very homogeneous but suffers from a bad set up.
One thing that puzzled me was the lack of progressive adaptation between the round throat of the Radian 950 compression driver and the square throat of the horn. This is a main source of diffraction at the throat and I think that some dirt things I could hear above 2kHz were probably due to this bad adaptation at throat. I found alos that the low mid lacked some presence in the beginning of the afternoon when a 6dB crossover was used and then when we turn the crossover to 18dB/octave the presence was better. A part of the partial lack of presence is IMHO due to the bad time alignment and therefore the bad pulse repsone of the overall system ( I noticed this on the note attack of the piano).
Also I think that the amplifiers were too much different one from the others and it was not the perfect match. The amplifiers were brought by different members of the association and never before they were used together. I did'nt like nor the class D amplifier used in the bass nor the SE KT 88 used for the high frequency range.
An interesting remark is that nobody complain about a too narrow directivity in the mid high frequencies (more than 20 persons were sitting in the listening room at 4 to 8 meters from the loudspeakers).
If you can have access to the following page, there is more discussion in French about that weekend at Mélaudia forum:
More http://forums.melaudia.net/showthread.php?tid=622
Best regards from Paris, France
Jean-Michel Le Cléac'h
angeloitacare said:hi Jean Michel
i guess you've overseen my last post, nr.113.
what i'm most like to know, i've asked there :
i am curious to know your listening impressions of the setup, you will be listening this weekend.
( with big LeCleac'h horn and Radian 950pb driver )
I've used in the past a tractrix horn with 23" , and a BMS 4592nd driver, covering from 300hz, all the way up. What most disturbed me, was beaming in the treble, and some sort of sound , which bothered me, which might be HOM's, but i'm not shure about this.
With the actual configuration, LeCleac'h/S2, i observe a much improved 3D imaging. And with the separate horn tweeter and wider dispertion, sound opens up - no complains anymore....
I had last weekend a friend of mine here, which uses to listen live classical concerts, and he brought a classic cd with orchestral music, he listens live. He was impressed how close my system sounded , compared to the live event.
Angelo
Attachments
Hello Angelo,
you wrote:
The BMS coaxial compression drivers should not IMHO be used in Hifi. Due to their building the 2 diaphragms, one circular for the HF and one as a ring for the LF, share the same throat. This is a very efficient source of diffraction (and Homs...) . I'll never recommand the use of coaxial compression drivers in Le Cléac'h horns as those horns are design to be quite diffraction free...
Best regards from Paris, France
Jean-Michel Le Cléac'h
you wrote:
angeloitacare said:
The BMS coaxial compression drivers should not IMHO be used in Hifi. Due to their building the 2 diaphragms, one circular for the HF and one as a ring for the LF, share the same throat. This is a very efficient source of diffraction (and Homs...) . I'll never recommand the use of coaxial compression drivers in Le Cléac'h horns as those horns are design to be quite diffraction free...
Best regards from Paris, France
Jean-Michel Le Cléac'h
Hello Bear,
It is often surprising as in a horn having a very continuous profile as the Le Cléac'h horn, the wavefront is able to drag (is it the proper word I don't know) along the wall until very large distance front the throat before to "lift off".
At low frequecny this effect is more pronounced than high frequency and the wavefront, as it expands, tends progressively to acquire a bubble shape and therefor a part of it is oriented backward.
This description is probably very bad (due to my lack of english vocabulary in various domains) so you may better give a look to the attached graph which one results from a simulation under Hornresp. On other simulations as
http://www.diyaudio.com/forums/attachment.php?s=&postid=1762170&stamp=1236072228
we can see that at high frequency (6000Hz here) there is still some pressure arriving at the edge of the mouth even for opening angle larger than 180degrees and this induces diffraction
Using opening angle larger than 270 degrees and if possible 360degrees is what I recommand, but unfortunately, most builders of Le Cléac'h horns stop at 200 or 220degrees.
The frequency response curves for Le Cléac'h horns without any filtering and crossover are pretty linear until the acoustical cut-off of the horn. But the phase rotate very quickly at frequency near the cut-off and this is equivalent to have a progressive delay of the lowest ferquencies.
For complexe signals as musical notes the fundamental or first harmonics of a note will arrive later than the upper harmonics and this will be audible (the timber will be different but also some people can feel as if the geometry of instrument was a bit strained or unatural).
Best regards from Paris, France
Jean-Michel Le Cléac'h
It is often surprising as in a horn having a very continuous profile as the Le Cléac'h horn, the wavefront is able to drag (is it the proper word I don't know) along the wall until very large distance front the throat before to "lift off".
At low frequecny this effect is more pronounced than high frequency and the wavefront, as it expands, tends progressively to acquire a bubble shape and therefor a part of it is oriented backward.
This description is probably very bad (due to my lack of english vocabulary in various domains) so you may better give a look to the attached graph which one results from a simulation under Hornresp. On other simulations as
http://www.diyaudio.com/forums/attachment.php?s=&postid=1762170&stamp=1236072228
we can see that at high frequency (6000Hz here) there is still some pressure arriving at the edge of the mouth even for opening angle larger than 180degrees and this induces diffraction
Using opening angle larger than 270 degrees and if possible 360degrees is what I recommand, but unfortunately, most builders of Le Cléac'h horns stop at 200 or 220degrees.
The frequency response curves for Le Cléac'h horns without any filtering and crossover are pretty linear until the acoustical cut-off of the horn. But the phase rotate very quickly at frequency near the cut-off and this is equivalent to have a progressive delay of the lowest ferquencies.
For complexe signals as musical notes the fundamental or first harmonics of a note will arrive later than the upper harmonics and this will be audible (the timber will be different but also some people can feel as if the geometry of instrument was a bit strained or unatural).
Best regards from Paris, France
Jean-Michel Le Cléac'h
bear said:
Attachments
Thanks JM,
nice to see the Onken W cassions in action. Ca me fait de bons souvenirs.
Those horns are, umm.... not small! They seem to have been well liked. So how are those big Radian drivers? They did well? I ask, because I just bought a pair of used Radain 1.4" drivers (at a good price). Hope they sound good.....
What was the driver on the treble horn?
From reading the posts on the Melaudia forum, it seems like you guys need a better treble amp. =) And I didn't know the Bryston was class-d.
Quite a system.
nice to see the Onken W cassions in action. Ca me fait de bons souvenirs.
Those horns are, umm.... not small! They seem to have been well liked. So how are those big Radian drivers? They did well? I ask, because I just bought a pair of used Radain 1.4" drivers (at a good price). Hope they sound good.....
What was the driver on the treble horn?
From reading the posts on the Melaudia forum, it seems like you guys need a better treble amp. =) And I didn't know the Bryston was class-d.
Quite a system.