And it never will be because it is not loading the compression driver properly, it is not coupling the driver to open air very well at all! It is trading efficiency for distortion. People are willing to put up with the distortion for the benefit of less coloration caused by deeper horn throat. I'm not at all sure that is a worthwhile trade, in fact I think that trade off sucks a lot. Please change my mind.
And on that subject, what is the best horn shape compromise if you are completely unwilling to give away efficiency? I would also mention that I am not willing to go beyond a 4 way, and I'm totally wanting to go modular, DIY with low cost drivers and stay upgradable. Not trying to go OT here I feel they are related issues.
That's actually not quite correct. The horn loading often leads to lower distortion is because you can keep the driver in its linear operating range and use the horn to increase its radiating efficiency. In other words, if you can drive the speaker less but get the same output, you're not likely to run into distortion as normal listening levels.
As far as most efficiency, it depends on the frequency range of interest. No one design is best for all applications.
As far as most efficiency, it depends on the frequency range of interest. No one design is best for all applications.
A wave guide is a horn. A horn isnt always a wave guide.
Wave guides increase efficiency by loading the driver and using a cap to get it back to flat lowers distortion.
This is the Seas 27-TDFC bare response
This is the lift with a small 6" wave guide (I used a 8" wide for the XT25 = more low end lift)
This is the response with a 3.3 cap on it:
Here is the bare tweeter distortion plot
Here is the distortion plot with guide and cap. The F2 distortion is down by 25db at 2000hz and the response is again flat on the tweeter. Its not just low in frequency. Since the harmonics generate the noise up top that theyre based on, the F2 is down 15db from 6-10k Hz. Whats really interesting is that the higher order distortion is based on whats happening from the low end hiccups and thus the F4 and F5 is sent to the floor on the top of the range.
As you can see the resulting response once back to flat has lower distortion by 25db.
Wave guides increase efficiency by loading the driver and using a cap to get it back to flat lowers distortion.
This is the Seas 27-TDFC bare response
This is the lift with a small 6" wave guide (I used a 8" wide for the XT25 = more low end lift)
This is the response with a 3.3 cap on it:
Here is the bare tweeter distortion plot
Here is the distortion plot with guide and cap. The F2 distortion is down by 25db at 2000hz and the response is again flat on the tweeter. Its not just low in frequency. Since the harmonics generate the noise up top that theyre based on, the F2 is down 15db from 6-10k Hz. Whats really interesting is that the higher order distortion is based on whats happening from the low end hiccups and thus the F4 and F5 is sent to the floor on the top of the range.
As you can see the resulting response once back to flat has lower distortion by 25db.
Thanks Leman23. I had gathered some of that. I am theorizing that shallow mid horns are not loading the driver nearly as much as deep ones in the area of most 'criticality", let say 400 to x000 and therefore they are going to generate more cone movement therefore more distortion. So I will make this more pointed. Lets say a deep exponential or radial horn vs, one of those very shallow cone things without a deep throat (OB or whatever) . What I am trying to put together is do what is the best compromise if you are in fact looking for the driver to move *less* or eve *the least* in that area but still have an acceptable radiation pattern? I'm guessing that once more PWK exponential or Altec radial might be the right choice, but have there been recent improvements which yield the same "less driver movement" for about these same radiation pattern and without diffraction artifacts? I surmise that shallow horns are not going to yield less driver distortion because they are more "spread" therefore I am not calling them horns any more and I accept that they are on fact mostly "guides" Yes I know that many will not choose this path and will live with the driver moving more for a perceived balance with the woofer. I think this might be the more important distinction between true horns and waveguides. And yes I do know this is a perfectly acceptable compromise for many. has there been a "true horn" no holds barred meeting of the minds "acceptable convention" realized recently? yeah, I know I ask the worst questions, but again, that is why we are here.
The idea is to get an even low end lift. The type of horn you're talking about like a tractrix horn (not a wave guide) is going to have colorations with uneven response that a simple cap wont counter. A wave guide tends to be shallow and really close to being time aligned with your midbass driver. Deeper freq lift will be with wider wave guides, not deeper.
Ok Thanks, Which type of horn will allow the driver to move the least? Lets start with a 500 to 8000k compression driver like the classic Atlas P5d/k55 on a flat circular say, 30 inch plane made out of rubber now lets mentally pull the entire circumference outward, leaving the driver in situ. At some point it is becoming a horn that optimally matches impedance of the driver to the air and moves less for a given output is that correct? Are you saying that the key is width, because one could simply sink a compression driver into the flat back wall and call that a horn then????? there must be some sort of optimum angle right? And I do mean optimum angle for efficiency within a given bandwidth.
I found a very nice horn theory summary, so I can stop asking dumb questions. (-;
https://www.grc.com/acoustics/an-introduction-to-horn-theory.pdf
https://www.grc.com/acoustics/an-introduction-to-horn-theory.pdf
When you're done with that you might read Earl Geddes's reply. If you dig around on his Gedlee website you can get the text of his Audio Transducers book and some really interesting papers on audibility of distortions generated by CD drivers and by time domain anomalies.
I think he and Danley are two guys it pays dividends to look at carefully.
I think he and Danley are two guys it pays dividends to look at carefully.
Well now after reading that a few times one thing is for certain. If you remotely understand the scale of this you know that small speakers without horns are always going to be a very poor compromise, and for that matter most of them with horns. B&W 801's weigh over 100 lbs they are small and inadequate, Compress dynamics pretty bad. the following still do but less so, Sentry III's Model 19's A7's etc. Even with the flaws of older horns.......The Khorn and a precious few others are probably about as small as you can get away with and still have most of the impact of a concert. I think Danley's Synergy probably are another candidate
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I think Earl Geddes is great I do follow him. I also think he may not be producing exactly the speaker he would truly like to be making, who is? but economic realities and scale are prohibitive, and somebody needs to market smaller well designed high efficiency speakers again. The other trouble is certain people object to big speakers in *ones living room that one paid for* this ain't the the era of guys like Wayne, Connery Sinatra. Imagine those guys getting run off ball-less into a "man cave". Danley....ha...> as far as I can tell, he now holds *the patent on speakers*. Yeah, that's exactly what I said. every one in the industry that I trust and has actually heard these things tells me the same story. That may actually be a new paradigm, but they are far from small and of course they can never be small, that is inevitable. They are point source. That is incredible.
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I built Khorn clones in the '60s. Still have them. Even like them tri-amped with DCX 2496 these days.
But modern implementations like Danley's and Geddes's are cleaner and have at least as great dynamic range.
If you want the concert illusion in a small form factor, then you have go to more channels than stereo but that's another topic, I think.
Some of the DIY guys are making relatively small Synergy type speakers and taking up the bass end with subs. See what this guy is doing http://www.diyaudio.com/forums/mult...e-bandpass-mid-unity-horn-18.html#post3477006
I don't know how small this kind of application might go. There are madmen trying to put them in cars...
But modern implementations like Danley's and Geddes's are cleaner and have at least as great dynamic range.
If you want the concert illusion in a small form factor, then you have go to more channels than stereo but that's another topic, I think.
Some of the DIY guys are making relatively small Synergy type speakers and taking up the bass end with subs. See what this guy is doing http://www.diyaudio.com/forums/mult...e-bandpass-mid-unity-horn-18.html#post3477006
I don't know how small this kind of application might go. There are madmen trying to put them in cars...
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Dynamic range. A but different than efficiency.
As a musician I appreciate dynamic range, we can do that with disgusting amounts of amp power and too much waste heat.
As a mixing mastering engineer I appreciate a good curve and direct radiators because that is what we all are cursed with.
As a fairly educated audiophile I know that efficiency combined with dynamic range is going to knock you out of your chair.That sonic signature warts and all is the sound of 105 db sensitive Klipschorns!!!! Another beast entirely. I think the Synergies might be able to get close to Khorns because of the multiple drivers.
I don't expect to hear any newer design 2 way albeit well executed conventional pro audio driver type speakers to be anything but among the best of a breed I am long, long familiar with as a musician. JBL has done some fine 2 way PA speakers, flat too, great crossovers design, great drivers, "quadratic" type throats, yadayada. The best easily could be used as hifi and I expect EG's speakers to be as good or better. As Geddes said, the goals are the same, and there is no reason not to use those compression and pro woofer type drivers for hifi. High end two ways are nothing really new to pros. It's good that Geddes is exposing them to more people. Wanna sell your KClones?
As a musician I appreciate dynamic range, we can do that with disgusting amounts of amp power and too much waste heat.
As a mixing mastering engineer I appreciate a good curve and direct radiators because that is what we all are cursed with.
As a fairly educated audiophile I know that efficiency combined with dynamic range is going to knock you out of your chair.That sonic signature warts and all is the sound of 105 db sensitive Klipschorns!!!! Another beast entirely. I think the Synergies might be able to get close to Khorns because of the multiple drivers.
I don't expect to hear any newer design 2 way albeit well executed conventional pro audio driver type speakers to be anything but among the best of a breed I am long, long familiar with as a musician. JBL has done some fine 2 way PA speakers, flat too, great crossovers design, great drivers, "quadratic" type throats, yadayada. The best easily could be used as hifi and I expect EG's speakers to be as good or better. As Geddes said, the goals are the same, and there is no reason not to use those compression and pro woofer type drivers for hifi. High end two ways are nothing really new to pros. It's good that Geddes is exposing them to more people. Wanna sell your KClones?
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Housekeeping note: There is no need to quote the entire post just above yours.That is not dynamic range as it pertains to sound reproduction. Your dynamic range is a ratio between the largest level you are able to measure, hear, discriminate, reproduce, whatever, and the smallest. The ear can discern literally from the sound of a pin dropping to a jet flying overhead. A loudspeaker, however, is not flexible enough to reproduce these sounds as we hear them. The speaker's dynamic range therefore is the ratio between the largest signal it can reproduce linearly and audibly, and the smallest. The largest part is easy. The smallest part is not, because sounds like people clearing their throats in the crowd, or musicians conversing quietly during passages are recorded at an incredibly small level compared to the program material. If your speaker is able to reproduce these sounds, then you can say it has great dynamic range. Horns are very good at this because since these are very small signals, the odds of hearing them are small over everything else UNLESS you can increase the speaker's ability to transmit that sound into the room at an audible level. Horns do such a thing.
One might think of it this way;
A horn has two normal working modes, the first is as an impedance matching or improving device which raises the electroacoustic efficiency.
This is more or less coupling the large dimension / radiation resistance of the big end of the horn to the small end where the driver is and often described as a transformer. This happens up to the point where the horn is about a wavelength in circumference is K=1 in old terms. Beyond that point, there is little change or advantage in having a larger horn so far as efficiency and is why the thumb rule for bass horns is for free space, the mouth should be 1 wl in circumference.
That impedance transformation is also governed by the rate of expansion, for example an exponential horn cannot expand faster than doubling its area every two feet or so if you want a 30Hz low corner or every 2.4 inches for a 300HZ cutoff etc. The shape of the expansion also comes into play in the loading vs frequency as fig 2 here shows ;
https://www.grc.com/acoustics/an-introduction-to-horn-theory.pdf
The upshot is that for 20KHz, the wl is so small ALL of the impedance matching is done well before the sound even reaches the driver exit, keep in mind that the 20Hz to 20KHz span covers a 1000:1 wl size ratio.
Obviously the horn still does something at 20KHz and that is to confine the radiation angle ( in the old days before hifi confusion was thought of as the waveguide range of operation).
AS the sound progresses towards the mouth, it reaches a point where the horn no longer governs the directivity. This point was identified by Don Keele in the mid 70’s and distilled into a thumb rule in this paper defining the pattern control loss point governed by the horn dimension and horn wall angle.
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1975-05 AES Preprint) - Whats So Sacred Exp Horns.pdf
It was in this era that the narrowing of the sound radiation an exponential shape horn as the frequency increased was understood and in situations where producing constant directivity was desired, lead to horns with much more of a straight wall which allowed the highest frequencies to project at rightly the same angles as the lower frequencies once above the pattern control loss point. Earl Geddes OS horns are an approach which has the slowest possible variation of angle which allowed greater loading at the lower frequencies while still producing a more constant radiation angle.
The more straight walled horns of the type Done Keele described above have a rapid initial expansion which slows as you move from the apex towards the mouth and so have comparatively poor acoustic loading.
About 15 years ago it was that fact that dawned on me which lead to trying to load drivers through the side walls of the horn where the expansion was more suitable for lower frequencies, leading to the Unity horns and then the modern Synergy horn approach.
Best,
Tom Danley
Yes, I get it and I expect the less like a deep horn (cone ish) that are and the more like a flat surface (a driver mounted in a wall) they are the worse they will be a doing it. Which is whay I expect that Klipsch Speaker are better at that than speakers with flatter cones as horns.
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