ZilchLab said:
Zilch,
That is possibly the most useful post in this entire thread.
For a broader understanding of these devices go herë:
http://en.wikipedia.org/wiki/Waveguide#Acoustic_waveguides
http://en.wikipedia.org/wiki/Waveguide_(acoustics)
WithTarragon said:
Sure I can do that, but if you read my Letter to the Editor on Honrs on my website it is explained there too.
Horns are called horns because they derive from Websters Horn Equation (actually the term Horn came first and the equation followed) but in the art, horns meant using this equation.
In my research, I found that this equation was lacking (at best, wrong at worst) and developed a new set of equations. This was in 1990. It would not have made much sense to call my equations "horn" equations because they are different, so I borrowed a phrase from RF (as noted) and used the NEW term "Waveguide" to highlight the fact that my equations were different. Prior to my 1990 paper on this subject there was no use of the term "Waveguide" in audio.
I couldn't copyright the term since it was generic.
Manufacturers liked the name and they wanted to show how "advanced" they were so they adopted some of my ideas, some more than others (like Peavey who actually copied it outright and patented it). But to my knowledge I am still the only one to use my original set of equations and to fully grasp the implications and intents of this development.
So I choose to highlight the fact that my approach is different than all others by calling mine "waveguides" and theres, what they are "diffraction horns". They won't like this of course, but I don't have to abandon my original usage of the term either.
I always think of "wave guide" as a device that does not alter the shape of the wave from, but rather a device that lets the wave flow though with minimum change a energy loss.
I think of "horns" as devices that create back pressure on the original vibrating diaphragm in the process of altering the wave front and pressure distribution to obtain a specific energy distribution pattern. I assume that more energy is lost in this process.
I think of "horns" as devices that create back pressure on the original vibrating diaphragm in the process of altering the wave front and pressure distribution to obtain a specific energy distribution pattern. I assume that more energy is lost in this process.
Horns will be smaller than WGs for same low cut off, will make do for many coverage patterns, and will sustain more SPL for less power than WGs as the octaves go up. Big plus points for complex strong reinforcement rigs.
That is what I (probably wrongly?) understood until now, and I think that is why the industry sticks to them, only trying to make them a little less harsh.
For HT to medium club sizes I don't see why we have to bother with horns and not adopt WGs.
That is what I (probably wrongly?) understood until now, and I think that is why the industry sticks to them, only trying to make them a little less harsh.
For HT to medium club sizes I don't see why we have to bother with horns and not adopt WGs.
salas said:
I'm not sure if I follow, or I don't agree. Cutoff is not a concept that I use because I don't think that it means anything. And I don't see why a waveguide can't have the same SPL as a horn. In fact our research has shown that because a waveguide sounds less harsh, and harshness grows with SPL, the waveguide can actually have more usable MaxSPL than a horn. We make this point in the discussion on www.Ai-audio.com.
Hello,
Horns and waveguides by themselves dont amplify (they don't bring more power).
Let's take take horns and waveguides having same axial length and diameter at mouth.
In the high frequency, where a circular disk becomes very directive, they'll be not a lot of difference between SPL for horns and waveguide, because in the 2 cases the wave will be (seemingly) not interacting with the wall of the horn or of the waveguide.
In the low frequency where the wavelength is large the wave interact (not the best word, I know) with the wall and horns and waveguide behave differently because in the case of the horn the throat expansion is slower than with the waveguide. This leads to an efficient acoustic loading of the diaphragm for the horn case and a quasi null loading of the diaphragm for the waveguide (and the conical horn also). This loading is what make the power conversion (electrical / acoustical) more efficient with the horn (he behaves as an acoustic transformer and adapt the high mechanical impedance of the diaphragm to the small acoustical impedance of the air at listener's position) . There is a first conclusion: waveguides becomes a difficult choice if you want to reach a low cut-off frequency.
In the medium frequency progressively the loading of the diaphragm brought by the waveguide rises and the SPL will became comparable with the horns.
Here is attached a graph allowing comparison of simulated SPL curves (power response in a 0,5 pi solid angle in Hornresp) for different waveguides and horns (same cut-off frequency for all the horns and same mouth diameter and axial length for the waveguide, the conical horn and the exponential horn).
TAD TD2001 compression driver modelisation is used in the simulations performed under Hornresp.
Best regards from Paris, France.
Jean-Michel Le Cléac'h
Horns and waveguides by themselves dont amplify (they don't bring more power).
Let's take take horns and waveguides having same axial length and diameter at mouth.
In the high frequency, where a circular disk becomes very directive, they'll be not a lot of difference between SPL for horns and waveguide, because in the 2 cases the wave will be (seemingly) not interacting with the wall of the horn or of the waveguide.
In the low frequency where the wavelength is large the wave interact (not the best word, I know) with the wall and horns and waveguide behave differently because in the case of the horn the throat expansion is slower than with the waveguide. This leads to an efficient acoustic loading of the diaphragm for the horn case and a quasi null loading of the diaphragm for the waveguide (and the conical horn also). This loading is what make the power conversion (electrical / acoustical) more efficient with the horn (he behaves as an acoustic transformer and adapt the high mechanical impedance of the diaphragm to the small acoustical impedance of the air at listener's position) . There is a first conclusion: waveguides becomes a difficult choice if you want to reach a low cut-off frequency.
In the medium frequency progressively the loading of the diaphragm brought by the waveguide rises and the SPL will became comparable with the horns.
Here is attached a graph allowing comparison of simulated SPL curves (power response in a 0,5 pi solid angle in Hornresp) for different waveguides and horns (same cut-off frequency for all the horns and same mouth diameter and axial length for the waveguide, the conical horn and the exponential horn).
TAD TD2001 compression driver modelisation is used in the simulations performed under Hornresp.
Best regards from Paris, France.
Jean-Michel Le Cléac'h
soongsc said:
Attachments
"Were all these taken with exactly the same setup? Mic and mic preamp etc?"
Hello soongsc
Yes all with the same CLIO rig over time.
"If the type of horn focusses energy into a smaller angle, it is true that those regions will have higher SPL. But I think if one calculate total acoustic energy, it will probably be less."
Look at the efficiency of the device and output in acoustic watts how can the overall be less if the power is greater?? Look at directivity and how spl goes up or down depending on the horn Q/Directivity
Rob
Hello soongsc
Yes all with the same CLIO rig over time.
"If the type of horn focusses energy into a smaller angle, it is true that those regions will have higher SPL. But I think if one calculate total acoustic energy, it will probably be less."
Look at the efficiency of the device and output in acoustic watts how can the overall be less if the power is greater?? Look at directivity and how spl goes up or down depending on the horn Q/Directivity
Rob
Jmmlc said:
Simply stated the simulations are wrong. My results don't do that and all existing evidence is contrary too. Its is simply absurd to believe that those simulations are accurate. If this is the analysis that people are using to analyze my concepts then its no wonder they are mislead.
salas said:
If there is no real benefit why the industry keeps breaking our balls with horns still? I protest for the thousands of hours of harsh SPL I was subjected to, for years in the field!!!
The answer is quite simple - sound quality does not matter in the marketplace. Its size - and waveguides are bigger - and cost (the two are the same). So manufacturers do "a little" to make their products "look" like they are progressing, but they keep very close to the "small and inexpensive". Even I have found that we all "talk" about how important sound quality is, but very very very few actually pay that much attention to it in their own systems. "WAF" is the universal reason given for why people don't use my designs. I just smile and say "OK":bs:
Hello Earl,
All the simulations I have performed using Hornresp gave pretty accurate results for the "Le Cleac'h flare horns".
If there is something wrong with Hornresp when simulating an oblate spheroidal waveguide then may be you should ask David McBean to verify and modify Hornresp.
There is a topic called "Hornresp" in diyAudio.com's forum "subwoofer".
Give a look at:
http://www.diyaudio.com/forums/showthread.php?postid=1510471#post1510471
Best regards from Paris, France
Jean-Michel Le Cléac'h
All the simulations I have performed using Hornresp gave pretty accurate results for the "Le Cleac'h flare horns".
If there is something wrong with Hornresp when simulating an oblate spheroidal waveguide then may be you should ask David McBean to verify and modify Hornresp.
There is a topic called "Hornresp" in diyAudio.com's forum "subwoofer".
Give a look at:
http://www.diyaudio.com/forums/showthread.php?postid=1510471#post1510471
Best regards from Paris, France
Jean-Michel Le Cléac'h
gedlee said:
The impulse looks funny. Normally the leading edge of the impulse should be going upward. If it goes downward, it's either the mic signal is inverted (as most Panasonic WM61 type mics), or driver related issues (haven't figured this out yet).Robh3606 said:
Hello soongsc
Yes all with the same CLIO rig over time.
Look at the efficiency of the device and output in acoustic watts how can the overall be less if the power is greater?? Look at directivity and how spl goes up or down depending on the horn Q/Directivity
Rob
SPL will rise with focus of energy when we measure one point in the range of focus, however, if we take the total energy radiated into half space, I think horns will amount to less acoustic energy compared with a wave guide the way I categorize the terminology.
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