Easier is to just click on his name here to get to that page.pooge said:
Ohh, this is interesting!
Magnatar: While I understand that you are pleased with yourself, it would be of benefit to the entire forum if you could possibly comport yourself with just a small amount of dignity.
Hello Magnetar,
In my last messages I try to understand why there is never a waveguide used to cover the 200Hz to 1000Hz interval of frequency.
The best audiophiles systems in the world all use straight circular horns. As an example see:
http://images.google.ca/imgres?imgu...prev=/images?q=Goto+SG38WNSSP&um=1&hl=en&sa=N
In those low frequency domains, directivity of the horn and directivity of a loudspeaker is nearly the same. Not something to orient a choice. But low distortion will be far less with a compression driver (see the excellent comments about Jeffrey Jackson's system at VSAC 2008).
Have you ever listened to an Azura horn 1meter in diameter loading a good compression driver or to a Goto driver on a more than 1 meter long straight horn? Another world!
(but this is only for home use not for a stadium)
Best regards from Paris, France
Jean-Michel Le Cleac'h
In my last messages I try to understand why there is never a waveguide used to cover the 200Hz to 1000Hz interval of frequency.
The best audiophiles systems in the world all use straight circular horns. As an example see:
http://images.google.ca/imgres?imgu...prev=/images?q=Goto+SG38WNSSP&um=1&hl=en&sa=N
In those low frequency domains, directivity of the horn and directivity of a loudspeaker is nearly the same. Not something to orient a choice. But low distortion will be far less with a compression driver (see the excellent comments about Jeffrey Jackson's system at VSAC 2008).
Have you ever listened to an Azura horn 1meter in diameter loading a good compression driver or to a Goto driver on a more than 1 meter long straight horn? Another world!
(but this is only for home use not for a stadium)
Best regards from Paris, France
Jean-Michel Le Cleac'h
Magnetar said:
Hello Earl,
Well, in disreagarding my question of how to design a waveguide in order to cover, let's say the 200Hz-100Hz interval, you probably lost a chance for you to to promote your waveguide.
Fundamentally my questionning is:
Most systems using OS waveguide are 2 ways system. Crossover between the bass loudspeaker and the driver loaded by the waveguide is around 1kHz.
In the interval of frequency (lets say over 2kHz) for which the waveguide is aimed to operate at best, when the listening is off axis at more than 15° the response fall at 5dB/5° (roughly, this is measured on fig. 5 of you paper in JAES June 1993).
In the same condition, when we consider the bass loudspeaker operating below 1kHz , roughly when listening off axis the fall in the SPL is roughly 0dB/5°.
The overall result is that the 2 ways system changes in its tonal balance when the auditor moves (we can agree that this is worst with other kind of horns but this is not the point here).
So my questionning was: may be there is a solution to enlarge the 5dB/5° characteristics in order it will be maintained down to 200Hz (fundamental of the human voice). And from this results my (probably badly written) question to you about how to design a waveguide able to go down to 160Hz.
Best regards from Paris, France
Jean-Michel Le Cléac'h
Well, in disreagarding my question of how to design a waveguide in order to cover, let's say the 200Hz-100Hz interval, you probably lost a chance for you to to promote your waveguide.
Fundamentally my questionning is:
Most systems using OS waveguide are 2 ways system. Crossover between the bass loudspeaker and the driver loaded by the waveguide is around 1kHz.
In the interval of frequency (lets say over 2kHz) for which the waveguide is aimed to operate at best, when the listening is off axis at more than 15° the response fall at 5dB/5° (roughly, this is measured on fig. 5 of you paper in JAES June 1993).
In the same condition, when we consider the bass loudspeaker operating below 1kHz , roughly when listening off axis the fall in the SPL is roughly 0dB/5°.
The overall result is that the 2 ways system changes in its tonal balance when the auditor moves (we can agree that this is worst with other kind of horns but this is not the point here).
So my questionning was: may be there is a solution to enlarge the 5dB/5° characteristics in order it will be maintained down to 200Hz (fundamental of the human voice). And from this results my (probably badly written) question to you about how to design a waveguide able to go down to 160Hz.
Best regards from Paris, France
Jean-Michel Le Cléac'h
gedlee said:
Jmmlc said:
Hello, I looked at the graph and it clearly showed your intention was to measure the horn well past 1K. That is why you equalized the top end no? In my experience with large tractrix horns (I have a 180 flare horn pair here) and compression drivers when used that high eq does not help the beaming. What I found is you must use progressively smaller horns as you go up in frequency if you don't want the beaming.
Now I have used the large Emilar refraction horn to cover 80 to 500 with the Emilar EC600 compression driver and although it was dynamic and had wide radiation in that range it was limited in output and a bit 'thin' sounding used that way. I eventually ditched the idea and went on to cones in horns, then cones on boards.
An externally hosted image should be here but it was not working when we last tested it.
If you notice the same profile is used for the low mid (EC600), mid(EC600) and treble horn (EA175)with a little fostex tweeter for high treble. Bass was three horn loaded 18's
Here is another attempt to widen the radiation using multi cells
An externally hosted image should be here but it was not working when we last tested it.
And large tractrix horns that beamed (TAD 4001)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Finally this worked best -
An externally hosted image should be here but it was not working when we last tested it.
Magnetar said:
Mmm.... That make sense. Unfortunately. My little Tractrix sound very good, but they beam. Maybe need to make smaller ones for up higher.
Any rule of thumb you've found for mouth size vs high end beaming?
BTW, I like the look of that last rig, something rather elegant about it.
panomaniac said:
I would use a small 1200 Hz flare with a 1" driver for treble if you are using a horn now that has say a 600 Hz flare
I liked that system but it didn't 'gel' like my open baffle systems. The open bass panels are far more free sounding or 'boxless'..I still like using a horn above 1.5k, the small 18 sound horn is a real sleeper.
Jmmlc said:
I didn't disregard your question, I told you why it was not important to me.
There "may be" a way to lower the directivity control, but that would necesitate an ill advised compromise in something else. As you stated yourself:
However I would strongly disagree with your last sentence as it is completely incorrect. A compression driver forced down to 160 Hz will have a huge excursion and lots of distortion while a larger piston source is operating in its region of minimum distortion. So if the directivity is the same but the piston source has lower distortion it would seem to me that even you would be using a piston source in the range of 200 Hz - 800 Hz.
And your numbers for off axis falloff are completely wrong. The response of my designs are down by about 10 dB at 45° or about 1 dB / 5° not the ridiculous 5 dB / 5° that you quoted. (see www.ai-audio.com) It's very difficult to have a decent discussion when you use data that is so far from reality.
Why don't you publish some full system polars of your systems so we can all see how well they work?
Its easy (and kind of pointless) to make statements like"
and show some pictures. But where is the data? The real proof of what you are saying? I have data and I have reviews to support my position.
Hello Magnetar,
The response curve given in the link was not mine's but was obtained by Martin Seddon in Australia.
If you look Marco Henry's Musique Concrète system (here in France) you'll see that he only use the large horn in the low-mid
http://www.musique-concrete.com/index/GCETF.jpg this sytem as the fex Goto systems I could listen and which use low-mid compression driver don't give a thin sound! In fact they give one of the most "natural" low-mid possible IMHO.
(please note that most of the top end Goto systems use 4 or 5 ways, this division of the audible range, probably leads to a better control of the overall directivity)
But if directivity is something one peculiar audiophile doesn't fear I can understand very easily that such horn as the Azura allowing a linear response from 200Hz to 18kHz will be used inside a 2 ways system.
Best regards from Paris, France
Jean-Michel Le Cléac'h
The response curve given in the link was not mine's but was obtained by Martin Seddon in Australia.
If you look Marco Henry's Musique Concrète system (here in France) you'll see that he only use the large horn in the low-mid
http://www.musique-concrete.com/index/GCETF.jpg this sytem as the fex Goto systems I could listen and which use low-mid compression driver don't give a thin sound! In fact they give one of the most "natural" low-mid possible IMHO.
(please note that most of the top end Goto systems use 4 or 5 ways, this division of the audible range, probably leads to a better control of the overall directivity)
But if directivity is something one peculiar audiophile doesn't fear I can understand very easily that such horn as the Azura allowing a linear response from 200Hz to 18kHz will be used inside a 2 ways system.
Best regards from Paris, France
Jean-Michel Le Cléac'h
Magnetar said:
" A compression driver forced down to 160 Hz will have a huge excursion and lots of distortion while a larger piston source is operating in its region of minimum distortion. So if the directivity is the same but the piston source has lower distortion it would seem to me that even you would be using a piston source in the range of 200 Hz - 800 Hz"
Have you looked at Cone Midrange Compression Drivers?? JBL uses them in the Applied Engineering line. It's hybrid using a direct radiator as a compression driver.
Rob🙂
Have you looked at Cone Midrange Compression Drivers?? JBL uses them in the Applied Engineering line. It's hybrid using a direct radiator as a compression driver.
Rob🙂
Hello Earl,
I am sorry I did an error while typing:
"at more than 15° the response fall at 5dB/5°"
I should have written:
"at more than 25° the response fall at 5dB/5°"
The graph from your JAES paper I used for that is in attached file with my measurements. If I am wrong I accept to be corrected...
Best regards from Paris, France
Jean-Michel Le Cléac'h
I am sorry I did an error while typing:
"at more than 15° the response fall at 5dB/5°"
I should have written:
"at more than 25° the response fall at 5dB/5°"
The graph from your JAES paper I used for that is in attached file with my measurements. If I am wrong I accept to be corrected...
Best regards from Paris, France
Jean-Michel Le Cléac'h
gedlee said:
Attachments
Jmmlc said:
That design is more than 20 years old! Why do you go to something that is obsolete and not my much more recent designs? This is not an open minded approach.
And beyond 30° I WANT the sound field to fall as fast as possible. Why do you imply this is a bad thing? You and I seem to have completely different ideas about sound reproduction.
Robh3606 said:
Of course I am aware of them and if I were doing a system for an auditorium I would indeed use a waveguide on one and take the pattern control down another octave or more. But thats NOT what I am designing for nor talking about at the moment.
What could be done is infinite. I did the Summa design for a very specific set of circumstances, namely a small room or club. In this situation I would claim my design to be optimal. I do not claim that it is optimal in ALL situations, nothing is.
For instance, for very high SPLs the Unity horn amkes a lot of sense to me. I can see where its tradeoffs are well matched to the very high SPL situation. But I would put my systems up against any unity horn in a small room. They will simply not be ideal in that situation.
Dr Geddes,
I have long been an admirer of your work and am very impressed with the power of your intellect (I train residents as an attending physician and think in terms of their raw "brain power" quite a bit). I read (what I could of it!) your Transducers book a few years ago and, as I said, was impressed.
I have to say, though that I am disappointed by your last response to JMMLC. I don't think he meant any disrespect and had some interesting questions re. directivity control (how low it is desired, etc.). He is also clearly attempting to understand and interpret your OS waveguides in the context of his (probably vast) experience with people who are pursuing full-range, or close to full-range horn systems, some of these with very exotic/expensive/large compression drivers.
While you may disagree with that approach, the why's and the discussion of it nonetheless is interesting to many. Using terms like "ridiculous," "completely incorrect/wrong" etc. is pretty tough/dismissive. I think if he made mistakes in interpretation of your posted data I would have initially assumed a simple mistake as being gentlemanly. I simply feel that you came off as disrespectful to someone who also seems to me to have a very good brain (who knows what kind of accomplishments he has in his primary field of work?!-remember most of us are hobbyists, bright folks with other full-time occupations who love music and music reproduction.) And remember also, he is communicating with us in our primary language, not his.
Sincerely,
Bill Brown
I have long been an admirer of your work and am very impressed with the power of your intellect (I train residents as an attending physician and think in terms of their raw "brain power" quite a bit). I read (what I could of it!) your Transducers book a few years ago and, as I said, was impressed.
I have to say, though that I am disappointed by your last response to JMMLC. I don't think he meant any disrespect and had some interesting questions re. directivity control (how low it is desired, etc.). He is also clearly attempting to understand and interpret your OS waveguides in the context of his (probably vast) experience with people who are pursuing full-range, or close to full-range horn systems, some of these with very exotic/expensive/large compression drivers.
While you may disagree with that approach, the why's and the discussion of it nonetheless is interesting to many. Using terms like "ridiculous," "completely incorrect/wrong" etc. is pretty tough/dismissive. I think if he made mistakes in interpretation of your posted data I would have initially assumed a simple mistake as being gentlemanly. I simply feel that you came off as disrespectful to someone who also seems to me to have a very good brain (who knows what kind of accomplishments he has in his primary field of work?!-remember most of us are hobbyists, bright folks with other full-time occupations who love music and music reproduction.) And remember also, he is communicating with us in our primary language, not his.
Sincerely,
Bill Brown
hello,
You see in that message a negative critical of the OS waveguide where there is nothing such from my part.
I simply ask if it is possible to have the same fall off-axis for an additional waveguide that will be used from 200Hz to 1000Hz...
Best regards from Paris, France
Jean-Michel Le Cléac'h
You see in that message a negative critical of the OS waveguide where there is nothing such from my part.
I simply ask if it is possible to have the same fall off-axis for an additional waveguide that will be used from 200Hz to 1000Hz...
Best regards from Paris, France
Jean-Michel Le Cléac'h
gedlee said:
I think there are many different opinions regarding how dispersion effects audible impressions. Mr. Linkwitz seems to think that reflections should have the same frequency balance in the reflections, which seem very different from the goals og gedlee. Whether these difference in relate with rooms size or not also remains to be fully understood. Unless we have all these different configurations in the same room where anyone can listen and compare, we must try to understand how each conludes to the opnion each may have.
Having changed off angle pattern of a driver, to achieve more gradual off-axis roll-off, I also had to equalize the response from about 1KHz up. The result were very interesting because people that listed were amazed why it sounded the same while moving around in a 3.3M x 3.3M room, and the sound was very pleasing even when listening from another room.
Unless time is taken to really compare the various wave guide/horns and also relate them with the in-room response, we are all still guessing what might be the best.
I once tried a design similar to the BEOLAB 5 with 180deg dispersion, the overall reverberation characteristics sounded very pleasing, but the diffraction and other issues made the design not so well clean with transients. Most of the transient parts of the music relate quite well with what we can see in the impulse. What makes me curious is that with the impulse data presented so far, I cannot see how the transient aspects of the music can be faithfully reproduced. Is this what must be sacrificed when we use horns or wave guides?
Having changed off angle pattern of a driver, to achieve more gradual off-axis roll-off, I also had to equalize the response from about 1KHz up. The result were very interesting because people that listed were amazed why it sounded the same while moving around in a 3.3M x 3.3M room, and the sound was very pleasing even when listening from another room.
Unless time is taken to really compare the various wave guide/horns and also relate them with the in-room response, we are all still guessing what might be the best.
I once tried a design similar to the BEOLAB 5 with 180deg dispersion, the overall reverberation characteristics sounded very pleasing, but the diffraction and other issues made the design not so well clean with transients. Most of the transient parts of the music relate quite well with what we can see in the impulse. What makes me curious is that with the impulse data presented so far, I cannot see how the transient aspects of the music can be faithfully reproduced. Is this what must be sacrificed when we use horns or wave guides?
Jean-Michel - I do appologize if I misinterpreted your intent. It did seem to me that you were trying to find holes in my designs where there were none by using obsolete data when new and far more relevent data is readily available. This did not appear to me to be an honest attempt to get answers, but more an attempt to obscure the discussion. If this is incorrect then I do appologize.
But I do stand by what I said even if I withdraw the way in which it was said. I see no reason to take a waveguide used in a small room below about 800 Hz, and I would much prefer to use a "good" large piston source in the 200 - 800 Hz region (for its directivity) than a compression driver in this situation.
I am very disappointed in the lack of truely useful data in regards to your designs. I will never accept simple statements about what something sounds like without some coraborating evidence. No one should ever be expected to to that - to simply accept something on faith.
But I do stand by what I said even if I withdraw the way in which it was said. I see no reason to take a waveguide used in a small room below about 800 Hz, and I would much prefer to use a "good" large piston source in the 200 - 800 Hz region (for its directivity) than a compression driver in this situation.
I am very disappointed in the lack of truely useful data in regards to your designs. I will never accept simple statements about what something sounds like without some coraborating evidence. No one should ever be expected to to that - to simply accept something on faith.
soongsc said:
This is incorrect. I agree with Mr. Linkwitz completely on this point. Stated another way - the axial response and the power response need to track one another. However, it is a misnomer that dipoles do this because they don't. A dipole has a changing directivity with frequency just as a direct radiator does, it's just that the dipole has an aditional Cos(theta) factor that the baffled piston doesn't. This additional factor is dominate at LF but the drivers directivity is dominate at HF. Only waveguides can approach the equivalence of direct and reverberant frequency response.
soongsc said:
How are they different? That's the very definition of constant directivity and uniform power response, no?
Outside the controlled sound field, however, we WANT it to fall away quickly to achieve an element of independence from the character of the room. We're not doing omnidirectional here; the objectives are different.
I can find my coffee cup in the impulse response. I'm not going to tune the system to it, though.
[Not my beer bottle, either.... 😀 ]
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